@article{mathieu-campbell_guo_grieshop_richmond-bryant_2024, title={Calibration of Low-Cost Particulate Matter Sensors PurpleAir: Model Development for Air Quality under High Relative Humidity Conditions}, url={https://doi.org/10.5194/egusphere-2024-1142}, DOI={10.5194/egusphere-2024-1142}, abstractNote={Abstract. The primary source of measurement error from the widely-used particulate matter (PM) PurpleAir sensors is ambient relative humidity (RH). Recently, the U.S. EPA developed a national correction model for PM2.5 concentrations measured by PurpleAir sensors (Barkjohn model). However, their study included few sites in the Southeastern U.S., the most humid region of the country. To provide high-quality spatial and temporal data and inform community exposure risks in this area, our study developed and evaluated PurpleAir correction models for use in the warm-humid climate zones of the U.S. We used hourly PurpleAir data and hourly reference grade PM2.5 data from the EPA Air Quality System database from January 2021 to August 2023. Compared with the Barkjohn model, we found improved performance metrics with error metrics decreasing by 16–23 % when applying a multi linear regression (MLR) model with RH and temperature as predictive variables. We also tested a novel semi-supervised clustering (SSC) method and found that a nonlinear effect between PM2.5 and RH emerges around a RH of 50 % with slightly greater accuracy. Therefore, our results suggested that a clustering approach might be more accurate in high humidity conditions to capture the non-linearity associated with PM particle hygroscopic growth.}, author={Mathieu-Campbell, Martine E. and Guo, Chuqi and Grieshop, Andrew P. and Richmond-Bryant, Jennifer}, year={2024}, month={May} }
 @article{mccord_parsons_bittner_jumbe_kabwe_pedit_serenje_grieshop_jagger_2024, title={Carbon Monoxide Exposure and Risk of Cognitive Impairment Among Cooks in Africa}, volume={2024}, ISSN={["1600-0668"]}, DOI={10.1155/2024/7363613}, journal={INDOOR AIR}, author={McCord, Ryan and Parsons, Stephanie and Bittner, Ashley S. and Jumbe, Charles B. L. and Kabwe, Gillian and Pedit, Joseph and Serenje, Nancy and Grieshop, Andrew P. and Jagger, Pamela}, year={2024}, month={Jun} }
 @article{floess_ercumen_harris_grieshop_2024, title={Do the Health Benefits of Boiling Drinking Water Outweigh the Negative Impacts of Increased Indoor Air Pollution Exposure?}, url={https://doi.org/10.1101/2024.03.22.24304348}, DOI={10.1101/2024.03.22.24304348}, abstractNote={Abstract}, author={Floess, Emily and Ercumen, Ayse and Harris, Angela and Grieshop, Andrew P.}, year={2024}, month={Mar} }
 @article{sinha_vazquez_ruiz-garcia_masera_grieshop_2024, title={Evaluating a simplified oxidation flow reactor configuration to characterize fresh and aged emissions from traditional and plancha-type cookstoves under field-like conditions}, volume={328}, ISSN={["1873-2844"]}, url={https://doi.org/10.1016/j.atmosenv.2024.120498}, DOI={10.1016/j.atmosenv.2024.120498}, abstractNote={Plancha-type stoves have been distributed for decades in Mexico to reduce household air pollution, but the influence of photochemical processing ('aging') of their emissions is unknown. Secondary organic aerosols (SOA), formed from aging biomass combustion emissions, has typically been studied in laboratories with complex setups and sophisticated instrumentation. Here, we present an evaluation of a simplified measurement approach using an oxidation flow reactor (OFR), portable instrumentation and filter samples, and its subsequent deployment in characterizing Plancha-type stove emissions in a simulated-field setting in Mexico. Evaluation of field-portable optical measurements for tracking SOA mass for a range of combustion conditions in a laboratory suggested that a field portable nephelometer/filter sampling instrument could effectively quantify time-varying fresh and aged organic aerosol (OA). However, these experiments showed that correction of the optical response with filter measurements was particularly important for aged aerosol. Next, we deployed this measurement ensemble with an OFR to measure fresh and aged emissions from two plancha-type stoves (Patsari and ONIL) and a traditional three stone fire (TSF) under field-like conditions at a test kitchen facility in Pátzcuaro, Mexico. Plancha-type stoves offered significant reductions in primary PM emissions factors (EFs) relative to TSF, with mean Patsari and ONIL elemental carbon, EC (organic matter, OM) EFs lower by ∼19% (65%) and ∼49%(83%) than TSF EFs, respectively. Further, mean Patsari and ONIL SOA emission factors (emission rates) were lower than TSF by 47% (46%) and 61% (73%), respectively, indicating that plancha stoves have the potential to reduce secondary PM formation along with fresh emissions. However, using an OFR to age time-varying real-world emissions is complex, as changes in emission concentrations and composition directly affect the OFR's chemistry, with the interaction between combustion efficiency and OH reactivity in the OFR influencing the extent of tropospheric aging emissions undergo. We outline the challenges associated with such real-time aging experiments and recommend strategies like implementing staged dilution of the flue gas or batch sampling in a smog chamber.}, journal={ATMOSPHERIC ENVIRONMENT}, author={Sinha, Aditya and Vazquez, Juan Carlos and Ruiz-Garcia, Victor and Masera, Omar and Grieshop, Andrew P.}, year={2024}, month={Jul} }
 @article{bittner_holder_grieshop_hagler_mitchell_2024, title={Performance of Vehicle Add-on Mobile Monitoring System PM<sub>2.5</sub> measurements during wildland fire episodes}, volume={4}, ISSN={["2634-3606"]}, url={https://doi.org/10.1039/D3EA00170A}, DOI={10.1039/D3EA00170A}, abstractNote={A universally attachable, lightweight PM2.5 mobile monitor provides reliable and actionable supplemental information on air quality conditions in communities impacted by wildland fire smoke via a nationwide loan program.}, number={3}, journal={ENVIRONMENTAL SCIENCE-ATMOSPHERES}, author={Bittner, Ashley S. and Holder, Amara L. and Grieshop, Andrew P. and Hagler, Gayle S. W. and Mitchell, William}, year={2024}, month={Mar}, pages={306–320} }
 @article{mathieu-campbell_guo_grieshop_richmond-bryant_2024, title={Supplementary material to "Calibration of Low-Cost Particulate Matter Sensors PurpleAir: Model Development for Air Quality under High Relative Humidity Conditions"}, url={https://doi.org/10.5194/egusphere-2024-1142-supplement}, DOI={10.5194/egusphere-2024-1142-supplement}, author={Mathieu-Campbell, Martine E. and Guo, Chuqi and Grieshop, Andrew P. and Richmond-Bryant, Jennifer}, year={2024}, month={May} }
 @article{dicarlo_berglund_kaza_grieshop_shealy_behr_2023, title={Customer complaint management and smart technology adoption by community water systems}, volume={80}, ISSN={["1878-4356"]}, DOI={10.1016/j.jup.2022.101465}, abstractNote={Community water systems (CWSs) supply safe drinking water through pipes and other conveyances to the same population year-round. Complaint management is an important activity for CWSs and can assist efforts to monitor water quality and improve public perceptions. This research explores how CWSs receive, store, and use customer complaints. A new dataset is constructed through the distribution of an online survey. Respondents represent more than 500 CWSs across the U.S. and vary in characteristics, including the population size served. This research gives new insight about the tools that CWSs need and are willing to adopt for analyzing and reporting water quality issues.}, journal={UTILITIES POLICY}, author={DiCarlo, Morgan and Berglund, Emily Zechman and Kaza, Nikhil and Grieshop, Andrew and Shealy, Luke and Behr, Adam}, year={2023}, month={Feb} }
 @article{floess_grieshop_puzzolo_pope_leach_smith_gill-wiehl_landesman_bailis_2023, title={Scaling up gas and electric cooking in low- and middle-income countries: climate threat or mitigation strategy with co-benefits?}, volume={18}, ISSN={["1748-9326"]}, url={https://doi.org/10.1088/1748-9326/acb501}, DOI={10.1088/1748-9326/acb501}, abstractNote={Abstract}, number={3}, journal={ENVIRONMENTAL RESEARCH LETTERS}, author={Floess, Emily and Grieshop, Andrew and Puzzolo, Elisa and Pope, Dan and Leach, Nicholas and Smith, Christopher J. and Gill-Wiehl, Annelise and Landesman, Katherine and Bailis, Rob}, year={2023}, month={Mar} }
 @article{kim_sinha_george_demarini_grieshop_gilmour_2023, title={Toxicity of fresh and aged anthropogenic smoke particles emitted from different burning conditions}, volume={892}, ISSN={["1879-1026"]}, DOI={10.1016/j.scitotenv.2023.164778}, abstractNote={There is substantial evidence that photochemical reactions in the atmosphere cause physico-chemical transformation of combustion smoke, but how this processing modifies potential health effects in exposed populations is not well understood. Here we utilized a new approach to simulate photochemical aging of anthropogenic smoke emissions (a mixture of plastic, plywood, and cardboard smoke) from two different burning conditions (smoldering vs. flaming) and investigated their adverse outcomes associated with mutagenic activity and the relative potencies of different polycyclic aromatic hydrocarbons (PAHs). Aging resulted in increased oxygenated volatile organic compound (VOC) emissions but largely degraded particle-bound PAH components in the smoke. Chemical transformation during aging was more dramatic for flaming versus smoldering smoke. Due to the PAH degradation, mutagenicity of the aged smoke from flaming combustion was much lower (up to 4 times) than that of the fresh smoke on per-particle mass basis. However, on the basis of particle emitted per fuel mass burned, the aged and fresh smoke particles exhibited similar mutagenic activities, which were up to 3 times higher for smoldering versus flaming smoke emissions. Similarly, the PAH toxicity equivalent (PAH-TEQ) of the aged smoldering smoke was 3 times higher than that of the aged flaming smoke particles, suggesting that some PAHs (e.g., indeno[c,d]pyrene and benzo[b]fluoranthene) in the smoldering smoke were more photochemically stable during aging. These findings increase understanding of the evolution of smoke emitted at different burning conditions and the role of photochemical transformations on mutagenicity and PAH-induced toxicity.}, journal={SCIENCE OF THE TOTAL ENVIRONMENT}, author={Kim, Yong Ho and Sinha, Aditya and George, Ingrid J. and DeMarini, David M. and Grieshop, Andrew P. and Gilmour, M. Ian}, year={2023}, month={Sep} }
 @article{islam_wathore_zerriffi_marshall_bailis_grieshop_2022, title={Assessing the Effects of Stove Use Patterns and Kitchen Chimneys on Indoor Air Quality during a Multiyear Cookstove Randomized Control Trial in Rural India}, volume={56}, ISSN={["1520-5851"]}, url={https://doi.org/10.1021/acs.est.1c07571}, DOI={10.1021/acs.est.1c07571}, abstractNote={We conducted indoor air quality (IAQ) measurements during a multiyear cookstove randomized control trial in two rural areas in northern and southern India. A total of 1205 days of kitchen PM2.5 were measured in control and intervention households during six ∼3 month long measurement periods across two study locations. Stoves used included traditional solid fuel (TSF), improved biomass, and liquefied petroleum gas (LPG) models. Intent-to-treat analysis indicates that the intervention reduced average 24 h PM2.5 and black carbon in only one of the two follow-up measurement periods in both areas, suggesting mixed effectiveness. Average PM2.5 levels were ∼50% lower in households with LPG (for exclusive LPG use: >75% lower) than in those without LPG. PM2.5 was 66% lower in households making exclusive use of an improved chimney stove versus a traditional chimney stove and TSF-exclusive kitchens with a built-in chimney had ∼60% lower PM2.5 than those without a chimney, indicating that kitchen ventilation can be as important as the stove technology in improving IAQ. Diurnal trends in real-time PM2.5 indicate that kitchen chimneys were especially effective at reducing peak concentrations, which leads to decreases in daily PM2.5 in these households. Our data demonstrate a clear hierarchy of IAQ improvement in real world, "stove-stacking" households, driven by different stove technologies and kitchen characteristics.}, number={12}, journal={ENVIRONMENTAL SCIENCE & TECHNOLOGY}, publisher={American Chemical Society (ACS)}, author={Islam, Mohammad Maksimul and Wathore, Roshan and Zerriffi, Hisham and Marshall, Julian D. and Bailis, Rob and Grieshop, Andrew P.}, year={2022}, month={Jun}, pages={8326–8337} }
 @article{floess_grieshop_puzzolo_pope_leach_smith_gill-wiehl_landesman_bailis_2022, title={Climate & Health Implications of Adopting Modern Household Cooking Fuels on a Global Scale}, url={https://doi.org/10.21203/rs.3.rs-2011721/v1}, DOI={10.21203/rs.3.rs-2011721/v1}, abstractNote={Abstract}, author={Floess, Emily and Grieshop, Andrew and Puzzolo, Elisa and Pope, Daniel and Leach, Nicholas and Smith, Christopher J. and Gill-Wiehl, Annelise and Landesman, Katherine and Bailis, Rob}, year={2022}, month={Sep} }
 @article{sinha_george_holder_preston_hays_grieshop_2022, title={Development of volatility distributions for organic matter in biomass burning emissions}, volume={10}, ISSN={["2634-3606"]}, url={https://doi.org/10.1039/D2EA00080F}, DOI={10.1039/D2EA00080F}, abstractNote={We present a novel filter-in-tube sorbent tube method to collect S/I-VOC samples from a range of biomass burning experiments and find that volatility distributions are relatively consistent with prior findings and across the tested combustion types.}, journal={ENVIRONMENTAL SCIENCE-ATMOSPHERES}, author={Sinha, Aditya and George, Ingrid and Holder, Amara and Preston, William and Hays, Michael and Grieshop, Andrew P.}, year={2022}, month={Oct} }
 @article{bittner_cross_hagan_malings_lipsky_grieshop_2022, title={Performance characterization of low-cost air quality sensors for off-grid deployment in rural Malawi}, volume={15}, ISSN={["1867-8548"]}, url={https://doi.org/10.5194/amt-15-3353-2022}, DOI={10.5194/amt-15-3353-2022}, abstractNote={Abstract. Low-cost gas and particulate matter sensor packages offer a compact,
lightweight, and easily transportable solution to address global gaps in air
quality (AQ) observations. However, regions that would benefit most from
widespread deployment of low-cost AQ monitors often lack the reference-grade
equipment required to reliably calibrate and validate them. In this study,
we explore approaches to calibrating and validating three integrated sensor
packages before a 1-year deployment to rural Malawi using colocation data
collected at a regulatory site in North Carolina, USA. We compare the
performance of five computational modeling approaches to calibrate the
electrochemical gas sensors: k-nearest neighbors (kNN) hybrid, random forest
(RF) hybrid, high-dimensional model representation (HDMR), multilinear
regression (MLR), and quadratic regression (QR). For the CO, Ox, NO,
and NO2 sensors, we found that kNN hybrid models returned the highest
coefficients of determination and lowest error metrics when validated.
Hybrid models were also the most transferable approach when applied to
deployment data collected in Malawi. We compared kNN hybrid calibrated CO
observations from two regions in Malawi to remote sensing data and found
qualitative agreement in spatial and annual trends. However, ARISense
monthly mean surface observations were 2 to 4 times higher than the remote
sensing data, partly due to proximity to residential biomass combustion activity
not resolved by satellite imaging. We also compared the performance of the
integrated Alphasense OPC-N2 optical particle counter to a filter-corrected
nephelometer using colocation data collected at one of our deployment sites
in Malawi. We found the performance of the OPC-N2 varied widely with
environmental conditions, with the worst performance associated with high
relative humidity (RH >70 %) conditions and influence from
emissions from nearby residential biomass combustion. We did not find
obvious evidence of systematic sensor performance decay after the 1-year
deployment to Malawi. Data recovery (30 %–80 %) varied by sensor and season
and was limited by insufficient power and access to resources at the remote
deployment sites. Future low-cost sensor deployments to rural, low-income settings would benefit from adaptable power systems, standardized sensor
calibration methodologies, and increased regional regulatory-grade
monitoring infrastructure.
                    }, number={11}, journal={ATMOSPHERIC MEASUREMENT TECHNIQUES}, author={Bittner, Ashley S. and Cross, Eben S. and Hagan, David H. and Malings, Carl and Lipsky, Eric and Grieshop, Andrew P.}, year={2022}, month={Jun}, pages={3353–3376} }
 @article{islam_neyestani_saleh_grieshop_2022, title={Quantifying brown carbon light absorption in real-world biofuel combustion emissions}, volume={56}, ISSN={["1521-7388"]}, url={https://doi.org/10.1080/02786826.2022.2051425}, DOI={10.1080/02786826.2022.2051425}, abstractNote={Abstract Biofuel combustion is an important source of particulate light absorbing organic carbon (OC), also known as brown carbon (BrC). We applied spectrophotometry to characterize methanol-extracted BrC from emission tests of ‘real-world’ biofuel combustion in India and Malawi, including wood stoves (‘traditional’, ‘improved’ and ‘chimney’) and artisanal charcoal kilns. Average mass absorption coefficient (MACbulk,λ) of extracted BrC was highest for ‘traditional’, followed by ‘improved’, ‘chimney’, and ‘charcoal’, at near-ultraviolet to blue wavelengths, with this order reversed for BrC absorption Angstrom exponent (AAE). MACbulk,λ in UV wavelengths was positively correlated with the elemental carbon to organic aerosol ratio (EC/OA), though the correlation was weaker than that observed in laboratory cookstove samples. BrC imaginary refractive indices (k) were anti-correlated with wavelength dependence (w), thus less wavelength dependent BrC had higher light absorptivity. MACbulk,λ correlated with the fraction of OC evolving at higher temperature steps in thermo-optical analysis, consistent with a link between BrC absorptivity and OC volatility, and suggesting that BrC absorption may be parameterized using existing OC data. Modeling analyses showed that BrC makes a strong contribution to overall absorption (average of 48% to 80% at 365 nm), and a strong negative correlation between EC/OA and the relative contribution of BrC to total aerosol (BrC + BC) light absorption; the latter trend is dominated by the quantity versus optical properties of BrC. The estimated direct radiative effect of BrC is approximately equal to that of BC for biofuel combustion emissions in India, highlighting the importance of BrC in the climate energy budget. Copyright © 2022 American Association for Aerosol Research}, number={6}, journal={AEROSOL SCIENCE AND TECHNOLOGY}, publisher={Informa UK Limited}, author={Islam, Mohammad Maksimul and Neyestani, Soroush E. and Saleh, Rawad and Grieshop, Andrew P.}, year={2022}, month={Mar} }
 @article{floess_grieshop_puzzolo_pope_leach_smith_gill-wiehl_landesman_bailis_2022, title={Scaling up Gas and Electric Cooking in Low- and Middle-Income Countries: Climate Threat or Mitigation Strategy with co-Benefits?}, url={https://doi.org/10.21203/rs.3.rs-2011721/v3}, DOI={10.21203/rs.3.rs-2011721/v3}, abstractNote={Abstract}, author={Floess, Emily and Grieshop, Andrew and Puzzolo, Elisa and Pope, Daniel and Leach, Nicholas and Smith, Christopher J. and Gill-Wiehl, Annelise and Landesman, Katherine and Bailis, Rob}, year={2022}, month={Nov} }
 @article{floess_grieshop_puzzolo_pope_leach_smith_gill-wiehl_landesman_bailis_2022, title={Scaling up Gas and Electric Cooking in Low- and Middle-Income Countries: Climate Threat or Mitigation Strategy with co-Benefits?}, url={https://doi.org/10.21203/rs.3.rs-2011721/v2}, DOI={10.21203/rs.3.rs-2011721/v2}, abstractNote={Abstract}, author={Floess, Emily and Grieshop, Andrew and Puzzolo, Elisa and Pope, Daniel and Leach, Nicholas and Smith, Christopher J. and Gill-Wiehl, Annelise and Landesman, Katherine and Bailis, Rob}, year={2022}, month={Nov} }
 @article{parsons_tanner_champion_grieshop_2022, title={The effects of modified operation on emissions from a pellet-fed, forced-draft gasifier stove}, volume={70}, ISSN={["2352-4669"]}, DOI={10.1016/j.esd.2022.08.004}, abstractNote={Traditional solid fuel cookstoves emit gas- and particle-phase pollutants that contribute to household air pollution, human disease, and climate impacts. Forced-draft semi-gasifier stoves are an attractive intermediate step to zero-emitting stoves due to their reported lower emissions in laboratory and field studies, and potential for increased availability in more rural locales. However, emissions from these stoves have been shown to be highly variable and sensitive to stove design, fuel type, secondary air velocity, and operation mode. We measured carbon monoxide (CO), particulate matter (PM2.5), organic and elemental carbon, and particle number (15–685 nm) emissions of the widely adopted Mimi Moto pellet-fed, gasifier stove for different operating conditions under two modified protocols, the Water Boiling Test (WBT) and an updated laboratory testing protocol ISO 19867-1 (ISO). We categorized operating conditions into three approaches: Startup (varying ignition material), Shutdown (varying fan speed during a 45-min burnout period), and Refuel (varying the height of charred pellets added for re-ignition). Refueling led to the largest and most variable emissions, but lab emissions were all lower than high field emissions (e.g., similar to those of traditional solid fuels) and remained primarily in ISO Tiers 5 and 4 for CO and PM2.5, aspirational and second-best, respectively. We find large relative differences in emissions when comparing our results to similar studies conducted with the Mimi Moto and ISO protocol, suggesting small operational differences can have large emissions implications. To minimize emissions, we recommend using kerosene for ignition, turning the fan off when pellets are done burning and flame has extinguished, and reigniting with fresh pellets instead of pellet char. Improved training and maintenance are needed in real-world applications to decrease the frequency of high-emission events. Tightly constrained testing and detection limits remain challenges to fully understanding factors contributing to these events.}, journal={ENERGY FOR SUSTAINABLE DEVELOPMENT}, author={Parsons, Stephanie and Tanner, Ky and Champion, Wyatt and Grieshop, Andrew}, year={2022}, month={Oct}, pages={259–271} }
 @article{islam_wathore_zerriffi_marshall_bailis_grieshop_2021, title={In-use emissions from biomass and LPG stoves measured during a large, multi-year cookstove intervention study in rural India}, volume={758}, ISSN={["1879-1026"]}, url={https://doi.org/10.1016/j.scitotenv.2020.143698}, DOI={10.1016/j.scitotenv.2020.143698}, abstractNote={We conducted an emission measurement campaign as a part of a multiyear cookstove intervention trial in two rural locations in northern and southern India. 253 uncontrolled cooking tests measured emissions in control and intervention households during three ~3-month-long measurement periods in each location. We measured pollutants including fine particulate matter (PM2.5), organic and elemental carbon (OC, EC), black carbon (BC) and carbon monoxide (CO) from stoves ranging from traditional solid fuel (TSF) to improved biomass stoves (rocket, gasifier) to liquefied petroleum gas (LPG) models. TSF stoves showed substantial variability in pollutant emission factors (EFs; g kg−1 wood) and optical properties across measurement periods. Multilinear regression modeling found that measurement period, fuel properties, relative humidity, and cooking duration are significant predictors of TSF EFs. A rocket stove showed moderate reductions relative to TSF. LPG stoves had the lowest pollutant EFs, with mean PM2.5 and CO EFs (g MJdelivered−1) >90% lower than biomass stoves. However, in-home EFs of LPG were substantially higher than lab EFs, likely influenced by non-ideal combustion performance, emissions from food and possible influence from other combustion sources. In-home emission measurements may depict the actual exposure benefits associated with dissemination of LPG stoves in real world interventions.}, journal={SCIENCE OF THE TOTAL ENVIRONMENT}, publisher={Elsevier BV}, author={Islam, Mohammad Maksimul and Wathore, Roshan and Zerriffi, Hisham and Marshall, Julian D. and Bailis, Rob and Grieshop, Andrew P.}, year={2021}, month={Mar} }
 @article{sinha_islam_grieshop_2021, title={Influence of Stove, Fuel, and Oxidation Flow Reactor Conditions on Aging of Laboratory-Generated Cookstove Emissions}, volume={5}, ISSN={["2472-3452"]}, url={https://doi.org/10.1021/acsearthspacechem.1c00081}, DOI={10.1021/acsearthspacechem.1c00081}, abstractNote={Oxidation flow reactor (OFR) experiments are a useful way to explore secondary organic aerosol (SOA) production during photochemical aging of biomass combustion emissions. Here, we extend previous work by studying SOA formed by emissions from three cookstoves used in low-income settings (Philips, Chulika, and three-stone fire (TSF)) while varying the fuel type (red Oak and loblolly Pine) and OFR operating conditions. Differences in SOA formation across fuel types were relatively minor, with SOA formation increases of <30% for Oak vs Pine experiments. Mass spectral fragments (f44, f43, and f60) from aged Oak and Pine emissions generally spanned the same continuum with combustion technology playing a larger role in dictating aged OA evolution than the fuel type. Combustion technology also has a much greater influence on net aerosol climate forcing relative to interfuel differences. The OFR was operated under "wet" and "dry" conditions, to study the impacts of more or less tropospherically relevant oxidation conditions on SOA formation, respectively. SOA formation did not vary dramatically across OFR conditions and was larger by up to 27% for the TSF and 5% for the Philips for "wet" operation. OA spectral differences were greater, with f44 up to 28% greater for "wet" operating conditions at similar levels of aging. Overall, changes in reactor operation were not sufficient to alter major conclusions from previous work where the OFR was operated under conditions similar to the "dry" conditions applied here. Positive matrix factorization analyses on SOA spectra identified two factors, a transient oxidation factor and a uniformly aged factor, which were similar across experiments.}, number={6}, journal={ACS EARTH AND SPACE CHEMISTRY}, publisher={American Chemical Society (ACS)}, author={Sinha, Aditya and Islam, Mohammad Maksimul and Grieshop, Andrew}, year={2021}, month={Jun}, pages={1575–1590} }
 @article{bittner_cross_hagan_malings_lipsky_grieshop_2021, title={Performance Characterization of Low-cost Air Quality Sensors for Off-grid Deployment in Rural Malawi}, url={https://doi.org/10.5194/amt-2021-372}, DOI={10.5194/amt-2021-372}, abstractNote={Abstract. Low-cost gas and particulate sensor packages offer a compact, lightweight, and easily transportable solution to address global gaps in air quality (AQ) observations. However, regions that would benefit most from widespread deployment of low-cost AQ monitors often lack the reference grade equipment required to reliably calibrate and validate them. In this study, we explore approaches to calibrating and validating three integrated sensor packages before a 1-year deployment to rural Malawi using collocation data collected at a regulatory site in North Carolina, USA. We compare the performance of five computational modelling approaches to calibrate the electrochemical gas sensors: k-Nearest Neighbor (kNN) hybrid, random forest (RF) hybrid, high-dimensional model representation (HDMR), multilinear regression (MLR), and quadratic regression (QR). For the CO, Ox, NO, and NO2 sensors, we found that kNN hybrid models returned the highest coefficients of determination and lowest error metrics when validated; they also appeared to be the most transferable approach when applied to field data collected in Malawi. We compared calibrated CO observations to remote sensing data in two regions in Malawi and found qualitative agreement in spatial and annual trends. However, the monthly mean surface observations were 2 to 4 times higher than the remote sensing data, possibly due to proximity to small-scale combustion activity not resolved by satellite imaging. We also compared the performance of the integrated Alphasense OPC-N2 optical particle counter to a filter-corrected nephelometer using collocation data collected at one of our deployment sites in Malawi. We found the performance of the OPC-N2 varied widely with environmental conditions, with the worst performance associated with high relative humidity (RH > 70 %) conditions and influence from emissions from nearby biomass cookstoves. We did not find obvious evidence of systematic sensor performance decay after the 1-year deployment to Malawi; however, overall data recovery was limited by insufficient power and access to technical resources at deployment sites. Future low-cost sensor deployments to rural Sub-Saharan Africa would benefit from adaptable power systems, standardized sensor calibration methodologies, and increased regulatory grade regional infrastructure.
                        }, author={Bittner, Ashley S. and Cross, Eben S. and Hagan, David H. and Malings, Carl and Lipsky, Eric and Grieshop, Andrew}, year={2021}, month={Nov} }
 @article{bittner_cross_hagan_malings_lipsky_grieshop_2021, title={Supplementary material to &quot;Performance Characterization of Low-cost Air Quality Sensors for Off-grid Deployment in Rural Malawi&quot;}, url={https://doi.org/10.5194/amt-2021-372-supplement}, DOI={10.5194/amt-2021-372-supplement}, author={Bittner, Ashley S. and Cross, Eben S. and Hagan, David H. and Malings, Carl and Lipsky, Eric and Grieshop, Andrew}, year={2021}, month={Nov} }
 @article{malings_westervelt_hauryliuk_presto_grieshop_bittner_beekmann_subramanian_2020, title={Application of Low-Cost Fine Particulate Mass Monitors to Convert Satellite Aerosol Optical Depth Measurements to Surface Concentrations in North America and Africa}, volume={3}, url={https://doi.org/10.5194/amt-2020-67}, DOI={10.5194/amt-2020-67}, abstractNote={Abstract. Low-cost particulate mass sensors provide opportunities to assess air quality at unprecedented spatial and temporal resolutions. Established traditional monitoring networks have limited spatial resolution and are frequently absent in less-developed countries (e.g. in sub-Saharan Africa). Satellites provide snapshots of regional air pollution, but require ground-truthing. Low-cost monitors can supplement and extend data coverage from these sources worldwide, providing a better overall air quality picture. We demonstrate such a multi-source data integration using two case studies. First, in Pittsburgh, Pennsylvania, both traditional monitoring and dense low-cost sensor networks are present, and are compared with satellite aerosol optical depth (AOD) data from NASA's MODIS system. We assess the performance of linear conversion factors for AOD to surface PM2.5 using both networks, and identify relative benefits provided by the denser low-cost sensor network. In particular, with 10 or more ground monitors in the city, there is a two-fold reduction in worst-case surface PM2.5 estimation mean absolute error compared to using only a single ground monitor. Second, in Rwanda, Malawi, and the Democratic Republic of the Congo, traditional ground-based monitoring is lacking and must be substituted with low-cost sensor data. Here, we assess the ability of regional-scale satellite retrievals and local-scale low-cost sensor measurements to complement each other. In Rwanda, we find that combining local ground monitoring information with satellite data provides a 40 % improvement (in terms of surface PM2.5 estimation accuracy) with respect to using ground monitoring data alone. Overall, we find that combining ground-based low-cost sensor and satellite data can improve and expand spatio-temporal air quality data coverage in both well-monitored and data-sparse regions.
                        }, publisher={Copernicus GmbH}, author={Malings, Carl and Westervelt, Daniel and Hauryliuk, Aliaksei and Presto, Albert A. and Grieshop, Andrew and Bittner, Ashley and Beekmann, Matthias and Subramanian, R.}, year={2020}, month={Mar} }
 @article{malings_westervelt_hauryliuk_presto_grieshop_bittner_beekmann_subramanian_2020, title={Application of low-cost fine particulate mass monitors to convert satellite aerosol optical depth to surface concentrations in North America and Africa}, volume={13}, ISSN={["1867-8548"]}, url={https://doi.org/10.5194/amt-13-3873-2020}, DOI={10.5194/amt-13-3873-2020}, abstractNote={Abstract. Low-cost particulate mass sensors provide opportunities to assess air quality at unprecedented spatial and temporal resolutions. Established traditional monitoring networks have limited spatial resolution and are simply absent in many major cities across sub-Saharan Africa (SSA). Satellites provide snapshots of regional air pollution but require ground-truthing. Low-cost monitors can supplement and extend data coverage from these sources worldwide, providing a better overall air quality picture. We investigate the utility of such a multi-source data integration approach using two case studies. First, in Pittsburgh, Pennsylvania, both traditional monitoring and dense low-cost sensor networks are compared with satellite aerosol optical depth (AOD) data from NASA's MODIS system, and a linear conversion factor is developed to convert AOD to surface fine particulate matter mass concentration (as PM2.5). With 10 or more ground monitors in Pittsburgh, there is a 2-fold reduction in surface PM2.5 estimation mean absolute error compared to using only a single ground monitor. Second, we assess the ability of combined regional-scale satellite retrievals and local-scale low-cost sensor measurements to improve surface PM2.5 estimation at several urban sites in SSA. In Rwanda, we find that combining local ground monitoring information with satellite data provides a 40 % improvement in surface PM2.5 estimation accuracy with respect to using low-cost ground monitoring data alone. A linear AOD-to-surface-PM2.5 conversion factor developed in Kigali, Rwanda, did not generalize well to other parts of SSA and varied seasonally for the same location, emphasizing the need for ongoing and localized ground-based monitoring, which can be facilitated by low-cost sensors. Overall, we find that combining ground-based low-cost sensor and satellite data, even without including additional meteorological or land use information, can improve and expand spatiotemporal air quality data coverage, especially in data-sparse regions.}, number={7}, journal={ATMOSPHERIC MEASUREMENT TECHNIQUES}, publisher={Copernicus GmbH}, author={Malings, Carl and Westervelt, Daniel M. and Hauryliuk, Aliaksei and Presto, Albert A. and Grieshop, Andrew and Bittner, Ashley and Beekmann, Matthias and Subramanian, R.}, year={2020}, month={Jul}, pages={3873–3892} }
 @article{malings_westervelt_hauryliuk_presto_grieshop_bittner_beekmann_subramanian_2020, title={Supplementary material to &quot;Application of Low-Cost Fine Particulate Mass Monitors to Convert Satellite Aerosol Optical Depth Measurements to Surface Concentrations in North America and Africa&quot;}, volume={3}, url={https://doi.org/10.5194/amt-2020-67-supplement}, DOI={10.5194/amt-2020-67-supplement}, publisher={Copernicus GmbH}, author={Malings, Carl and Westervelt, Daniel and Hauryliuk, Aliaksei and Presto, Albert A. and Grieshop, Andrew and Bittner, Ashley and Beekmann, Matthias and Subramanian, R.}, year={2020}, month={Mar} }
 @misc{tallis_kreis_olander_ringler_ameyaw_borsuk_fletschner_game_gilligan_jeuland_et al._2019, title={Aligning evidence generation and use across health, development, and environment}, volume={39}, ISSN={["1877-3443"]}, DOI={10.1016/j.cosust.2019.09.004}, abstractNote={Although health, development, and environment challenges are interconnected, evidence remains fractured across sectors due to methodological and conceptual differences in research and practice. Aligned methods are needed to support Sustainable Development Goal advances and similar agendas. The Bridge Collaborative, an emergent research-practice collaboration, presents principles and recommendations that help harmonize methods for evidence generation and use. Recommendations were generated in the context of designing and evaluating evidence of impact for interventions related to five global challenges (stabilizing the global climate, making food production sustainable, decreasing air pollution and respiratory disease, improving sanitation and water security, and solving hunger and malnutrition) and serve as a starting point for further iteration and testing in a broader set of contexts and disciplines. We adopted six principles and emphasize three methodological recommendations: (1) creation of compatible results chains, (2) consideration of all relevant types of evidence, and (3) evaluation of strength of evidence using a unified rubric. We provide detailed suggestions for how these recommendations can be applied in practice, streamlining efforts to apply multi-objective approaches and/or synthesize evidence in multidisciplinary or transdisciplinary teams. These recommendations advance the necessary process of reconciling existing evidence standards in health, development, and environment, and initiate a common basis for integrated evidence generation and use in research, practice, and policy design.}, journal={CURRENT OPINION IN ENVIRONMENTAL SUSTAINABILITY}, author={Tallis, Heather and Kreis, Katharine and Olander, Lydia and Ringler, Claudia and Ameyaw, David and Borsuk, Mark E. and Fletschner, Diana and Game, Edward and Gilligan, Daniel O. and Jeuland, Marc and et al.}, year={2019}, month={Aug}, pages={81–93} }
 @article{rothfuss_petters_champion_grieshop_petters_2019, title={Characterization of a dimer preparation method for nanoscale organic aerosol}, volume={53}, ISSN={["1521-7388"]}, url={https://doi.org/10.1080/02786826.2019.1623379}, DOI={10.1080/02786826.2019.1623379}, abstractNote={Abstract Nanoscale dimers have application in studies of aerosol physicochemical properties such as aerosol viscosity. These particle dimers can be synthesized using the dual tandem differential mobility analyzer (DTDMA) technique, wherein oppositely charged particle streams coagulate to form dimers that can be isolated using electrostatic filtration. Although some characterization of the technique has been published, a detailed thesis on the modes and theory of operation has remained outside the scope of prior work. Here, we present new experimental data characterizing the output DTDMA size distribution and the physical processes underlying its apparent modes. Key experimental limitations for both general applications and for viscosity measurements are identified and quantified in six distinct types of DTDMA experiments. The primary consideration is the production of an adequate number of dimers, which typically requires high mobility-selected number concentration in the range 25,000–100,000 cm−3. The requisite concentration threshold depends upon the rate of spontaneous monomer decharging, which arises predominately from interactions of the aerosol with ionizing radiation within the coagulation chamber and is instrument location dependent. Lead shielding of the coagulation chamber reduced the first-order decharging constant from ∼2.0 × 10−5 s−1 to ∼0.8 × 10−5 s−1 in our laboratory. Dimer production at monomer diameters less than 40 nm is hindered by low bipolar charging efficiency. Results from the characterization experiments shed light on design considerations for general applications and for characterization of viscous aerosol phase transitions. Copyright © 2019 American Association for Aerosol Research}, number={9}, journal={AEROSOL SCIENCE AND TECHNOLOGY}, publisher={Informa UK Limited}, author={Rothfuss, Nicholas E. and Petters, Sarah S. and Champion, Wyatt M. and Grieshop, Andrew P. and Petters, Markus D.}, year={2019}, month={Sep}, pages={998–1011} }
 @article{menghwani_zerriffi_dwivedi_marshall_grieshop_bailis_2019, title={Determinants of Cookstoves and Fuel Choice Among Rural Households in India}, volume={16}, ISSN={["1612-9210"]}, DOI={10.1007/s10393-018-1389-3}, abstractNote={Roughly 2.8 billion people depend on solid fuels for cooking needs, resulting in a tremendous burden of disease from exposure to household air pollution. Despite decades of effort to promote cleaner cooking technologies, displacement of polluting technologies has progressed slowly. This paper describes results of a randomized controlled trial in which eight communities in two regions of rural India were presented with a range of cooking choices including improved solid fuel stoves and clean cooking options like liquefied petroleum gas (LPG) and induction stoves. Using survey data and logistic and multinomial regression, we identify factors associated with two outcomes: (1) pre-intervention ownership of non-solid fuel technologies and (2) household preferences for clean fuels from the range of cooking options offered. The analysis allows us to examine the influence of education, wealth, gender empowerment, stove pricing, and stove exchanges, among other variables. The majority of participants across all communities selected the cleanest options, LPG and induction, irrespective of price, but there is some variation in preferences. Wealth and higher caste stand out as significant predictors of pre-intervention ownership and non-solid fuel cooking options as well as preference for cleaner technologies offered through the intervention. The experimental treatments also influence preferences in some communities. When given the opportunity to exchange, communities in one region are more likely to choose solid fuel stoves (P < 0.05). Giving free stoves had mixed results; households in one region are more likely to select clean options (P < 0.05), but households in the other region prefer solid fuels (P < 0.10).}, number={1}, journal={ECOHEALTH}, author={Menghwani, Vikas and Zerriffi, Hisham and Dwivedi, Puneet and Marshall, Julian D. and Grieshop, Andrew and Bailis, Rob}, year={2019}, month={Mar}, pages={21–60} }
 @article{champion_grieshop_2019, title={Pellet-Fed Gasifier Stoves Approach Gas-Stove Like Performance during in-Home Use in Rwanda}, volume={53}, ISSN={["1520-5851"]}, url={https://doi.org/10.1021/acs.est.9b00009}, DOI={10.1021/acs.est.9b00009}, abstractNote={Nearly all households in Rwanda burn solid fuels for cooking. A private firm in Rwanda is distributing forced-draft pellet-fed semigasifier cookstoves and fuel pellets. We measured in-use emissions of pollutants including fine particulate matter (PM2.5), organic and elemental carbon (OC, EC), black carbon (BC), and carbon monoxide (CO) in 91 uncontrolled cooking tests (UCTs) of both pellet and baseline (wood; charcoal) stoves. We observed >90% reductions in most pollutant emission factors/rates from pellet stoves compared to baseline stoves. Pellet stoves performed far better than gasifier stoves burning unprocessed wood, and consistent with ISO tiers 4 and 5 for PM2.5 and CO, respectively. Pellet stoves were generally clean, but performance varied; emissions from the dirtiest pellet tests matched those from the cleanest traditional stove tests. Our real-time data suggest that events occurring during ignition and the end of testing (e.g., refueling, char burnout) drive high emissions during pellet tests. We use our data to estimate potential health and climate cobenefits from stove adoption. This analysis suggests that pellet stoves have the potential to provide health benefits far above previously tested biomass stoves and approaching modern fuel stoves (e.g., LPG). Net climate impacts of pellet stoves range from similar to LPG to negligible, depending on biomass source and upstream emissions.}, number={11}, journal={ENVIRONMENTAL SCIENCE & TECHNOLOGY}, publisher={American Chemical Society (ACS)}, author={Champion, Wyatt M. and Grieshop, Andrew P.}, year={2019}, month={Jun}, pages={6570–6579} }
 @article{petters_kreidenweis_grieshop_ziemann_petters_2019, title={Temperature- and Humidity-Dependent Phase States of Secondary Organic Aerosols}, volume={46}, ISSN={["1944-8007"]}, url={https://doi.org/10.1029/2018GL080563}, DOI={10.1029/2018GL080563}, abstractNote={Abstract}, number={2}, journal={GEOPHYSICAL RESEARCH LETTERS}, publisher={American Geophysical Union (AGU)}, author={Petters, Sarah S. and Kreidenweis, Sonia M. and Grieshop, Andrew P. and Ziemann, Paul J. and Petters, Markus D.}, year={2019}, month={Jan}, pages={1005–1013} }
 @article{champion_rothfuss_petters_grieshop_2019, title={Volatility and Viscosity Are Correlated in Terpene Secondary Organic Aerosol Formed in a Flow Reactor}, volume={6}, ISSN={["2328-8930"]}, url={https://doi.org/10.1021/acs.estlett.9b00412}, DOI={10.1021/acs.estlett.9b00412}, abstractNote={Secondary organic aerosol (SOA) is a complex mixture of largely unspeciated compounds. The volatility and viscosity of the bulk organic aerosol influence new particle formation, processing, and lifetime in the atmosphere. Relationships between these properties are well-defined for pure compounds but currently unavailable for bulk organic aerosol. In this survey study, we characterized SOA formed from a range of biogenic precursors and conditions in an oxidation flow reactor for volatility (thermodenuder), viscosity (dimer coagulation, isolation, and coalescence), and oxidation state (aerosol chemical speciation monitor). We find linear trends in log–linear and log–log plots of single-parameter representations of volatility and viscosity, with higher condensed-phase fractions of extremely low and low volatility material associated with an increased viscosity (R = 0.69). Per this relationship, an increase in the contribution of these fractions (i.e., lower volatility) by 0.1 results in an increase in viscos...}, number={9}, journal={ENVIRONMENTAL SCIENCE & TECHNOLOGY LETTERS}, publisher={American Chemical Society (ACS)}, author={Champion, Wyatt M. and Rothfuss, Nicholas E. and Petters, Markus D. and Grieshop, Andrew P.}, year={2019}, month={Sep}, pages={513–519} }
 @article{saha_khlystov_snyder_grieshop_2018, title={Characterization of air pollutant concentrations, fleet emission factors, and dispersion near a North Carolina interstate freeway across two seasons}, volume={177}, ISSN={["1873-2844"]}, url={https://doi.org/10.1016/j.atmosenv.2018.01.019}, DOI={10.1016/j.atmosenv.2018.01.019}, abstractNote={We present field measurement data and modeling of multiple traffic-related air pollutants during two seasons at a site adjoining Interstate 40, near Durham, North Carolina. We analyze spatial-temporal and seasonal trends and fleet-average pollutant emission factors and use our data to evaluate a line source dispersion model. Month-long measurement campaigns were performed in summer 2015 and winter 2016. Data were collected at a fixed near-road site located within 10 m from the highway edge, an upwind background site and, under favorable meteorological conditions, along downwind perpendicular transects. Measurements included the size distribution, chemical composition, and volatility of submicron particles, black carbon (BC), nitrogen oxides (NOx), meteorological conditions and traffic activity data. Results show strong seasonal and diurnal differences in spatial distribution of traffic sourced pollutants. A strong signature of vehicle emissions was observed within 100–150 m from the highway edge with significantly higher concentrations during morning. Substantially higher concentrations and less-sharp near-road gradients were observed in winter for many species. Season-specific fleet-average fuel-based emission factors for NO, NOx, BC, and particle number (PN) were derived based on up- and down-wind roadside measurements. The campaign-average NOx and PN emission factors were 20% and 300% higher in winter than summer, respectively. These results suggest that the combined effect of higher emissions and their slower downwind dispersion in winter dictate the observed higher downwind concentrations and wider highway influence zone in winter for several species. Finally, measurements of traffic data, emission factors, and pollutant concentrations were integrated to evaluate a line source dispersion model (R-LINE). The dispersion model captured the general trends in the spatial and temporal patterns in near-road concentrations. However, there was a tendency for the model to under-predict concentrations near the road in the mornings and over-predict concentrations in the evenings.}, journal={ATMOSPHERIC ENVIRONMENT}, publisher={Elsevier BV}, author={Saha, Provat K. and Khlystov, Andrey and Snyder, Michelle G. and Grieshop, Andrew P.}, year={2018}, month={Mar}, pages={143–153} }
 @article{rosenthal_quinn_grieshop_pillarisetti_glass_2018, title={Clean cooking and the SDGs: Integrated analytical approaches to guide energy interventions for health and environment goals}, volume={42}, ISSN={["2352-4669"]}, DOI={10.1016/j.esd.2017.11.003}, abstractNote={Development and implementation of clean cooking technology for households in low and middle income countries (LMICs) offer enormous promise to advance at least five Sustainable Development Goals (SDGs): 3. Good health and well-being; 5. Gender equality; 7. Affordable and clean energy; 13. Climate action; 15. Life on land. Programs are being implemented around the world to introduce alternative cooking technologies, and we are well on the way to achieving the goal set by the Global Alliance for Clean Cookstoves to reach 100 million homes with cleaner and more efficient cooking methods by 2020. Despite evidence that household air pollution (HAP) from solid fuel combustion is responsible for 3-4 million early deaths per year, many cookstove programs are motivated and/or financed by climate change mitigation schemes and deploy alternative stoves that use solid fuels such as wood and charcoal. However, recent studies have demonstrated that improved biomass-burning stoves typically only incrementally improve air quality and yield modest or minimal health benefits. Likewise, their contributions to climate change mitigation and other SDGs may be limited. Evidence indicates that cleaner fuels, such as liquefied petroleum gas (LPG), ethanol and biogas, offer greater potential benefits not only to health, but also greater progress towards climate goals and other relevant SDGs. We present a modeled estimate of these potential gains for a diverse group of 40 LMICs. Our model suggests that cookstove programs using LPG stoves and fuel will yield greater reductions in both Disability Adjusted Life Years and Global Warming Commitment in these countries than those using improved biomass stoves. Cost and infrastructure requirements for clean fuels such as LPG are widely recognized constraints. In view of these constraints we present an analytical method to simultaneously consider health and climate needs at the national level for the same 40 countries in the context of estimated LPG expansion potentials. Comparative analyses integrating priorities across SDGs at the national and regional levels may guide more practical and effective household energy development choices going forward.}, journal={ENERGY FOR SUSTAINABLE DEVELOPMENT}, author={Rosenthal, Joshua and Quinn, Ashlinn and Grieshop, Andrew P. and Pillarisetti, Ajay and Glass, Roger I.}, year={2018}, month={Feb}, pages={152–159} }
 @article{saha_khlystov_grieshop_2018, title={Downwind evolution of the volatility and mixing state of near-road aerosols near a US interstate highway}, volume={18}, ISSN={["1680-7324"]}, url={https://doi.org/10.5194/acp-18-2139-2018}, DOI={10.5194/acp-18-2139-2018}, abstractNote={Abstract. We present spatial measurements of particle volatility and mixing state at a site near a North Carolina interstate highway (I-40) applying several heating (thermodenuder; TD) experimental approaches. Measurements were conducted in summer 2015 and winter 2016 in a roadside trailer (10 m from road edge) and during downwind transects at different distances from the highway under favorable wind conditions using a mobile platform. Results show that the relative abundance of semi-volatile species (SVOCs) in ultrafine particles decreases with downwind distance, which is consistent with the dilution and mixing of traffic-sourced particles with background air and evaporation of semi-volatile species during downwind transport. An evaporation kinetics model was used to derive particle volatility distributions by fitting TD data. While the TD-derived distribution apportions about 20–30 % of particle mass as semi-volatile (SVOCs; effective saturation concentration, C∗ ≥ 1µm−3) at 10 m from the road edge, approximately 10 % of particle mass is attributed to SVOCs at 220 m, showing that the particle-phase semi-volatile fraction decreases with downwind distance. The relative abundance of semi-volatile material in the particle phase increased during winter. Downwind spatial gradients of the less volatile particle fraction (that remaining after heating at 180 °C) were strongly correlated with black carbon (BC). BC size distribution and mixing state measured using a single-particle soot photometer (SP2) at the roadside trailer showed that a large fraction (70–80 %) of BC particles were externally mixed. Heating experiments with a volatility tandem differential mobility analyzer (V-TDMA) also showed that the nonvolatile fraction in roadside aerosols is mostly externally mixed. V-TDMA measurements at different distances downwind from the highway indicate that the mixing state of roadside aerosols does not change significantly (e.g., BC mostly remains externally mixed) within a few hundred meters from the highway. Our analysis indicates that a superposition of volatility distributions measured in laboratory vehicle tests and of background aerosol can be used to represent the observed partitioning of near-road particles. The results from this study show that exposures and impacts of BC and semi-volatile organics-containing particles in a roadside microenvironment may differ across seasons and under changing ambient conditions.
                    }, number={3}, journal={ATMOSPHERIC CHEMISTRY AND PHYSICS}, publisher={Copernicus GmbH}, author={Saha, Provat K. and Khlystov, Andrey and Grieshop, Andrew P.}, year={2018}, month={Feb}, pages={2139–2154} }
 @article{kelp_grieshop_reynolds_baumgartner_jain_sethuraman_marshall_2018, title={Real-time indoor measurement of health and climate-relevant air pollution concentrations during a carbon-finance-approved cookstove intervention in rural India}, volume={3}, ISSN={2352-7285}, url={http://dx.doi.org/10.1016/j.deveng.2018.05.001}, DOI={10.1016/j.deveng.2018.05.001}, abstractNote={Biomass combustion in residential cookstoves is a major source of air pollution and a large contributor to the global burden of disease. Carbon financing offers a potential funding source for health-relevant energy technologies in low-income countries. We conducted a randomized intervention study to evaluate air pollution impacts of a carbon-finance-approved cookstove in rural South India. Prior research on this topic often has used time-integrated measures of indoor air quality. Here, we employed real-time monitors (∼24 h measurement at ∼ minute temporal resolution), thereby allowing investigation of minutely and hourly temporal patterns. We measured indoor concentrations of fine particulate matter (PM2.5), black carbon (BC) and carbon monoxide (CO) in intervention households (used newer, rocket-type stoves) and control households (“nonintervention”; continued using traditional open fire stoves). Some intervention households elected not to use only the new, intervention stoves (i.e., elected not to follow the study-design protocol); we therefore conducted analysis for “per protocol” versus “intent to treat.” We compared 24 h averages of air pollutants versus cooking hours only averages. Implementation of the per protocol intervention cookstove decreased median concentrations of CO (by 1.5 ppm (2.8 − 1.3; control − per protocol), p = 0.28) and PM2.5 (by 148 μg/m3 (365 − 217), p = 0.46) but increased BC concentration (by 39 μg/m3 (26 − −12), p < 0.05) and the ratio of BC/PM2.5 (by 0.25 (−0.28 − −0.03), p < 0.05) during cooking-relevant hours-of-day relative to controls. Calculated median effective air exchange rates based on decay in CO concentrations were stable between seasons (season 1: 2.5 h−1, season 2: 2.8 h−1). Finally, we discuss an analytical framework for evaluating real-time indoor datasets with limited sample sizes. For the present study, use of real-time (versus time-averaged) equipment substantially reduced the number of households we were able to monitor.}, journal={Development Engineering}, publisher={Elsevier BV}, author={Kelp, Makoto M. and Grieshop, Andrew P. and Reynolds, Conor C.O. and Baumgartner, Jill and Jain, Grishma and Sethuraman, Karthik and Marshall, Julian D.}, year={2018}, pages={125–132} }
 @article{saha_reece_grieshop_2018, title={Seasonally Varying Secondary Organic Aerosol Formation From In-Situ Oxidation of Near-Highway Air}, volume={52}, ISSN={["1520-5851"]}, url={https://doi.org/10.1021/acs.est.8b01134}, DOI={10.1021/acs.est.8b01134}, abstractNote={The extent to which motor vehicles contribute to ambient secondary organic aerosol (SOA) remains uncertain. Here, we present in situ measurements of SOA formation at a near-highway site with substantial tree-cover 10 m from Interstate 40 near Durham, North Carolina. In July 2015 (summer) and February 2016 (winter), we exposed ambient air to a range of oxidant (O3 and OH) concentrations in an oxidation flow reactor (OFR), resulting in hours to weeks of equivalent atmospheric aging. We observed substantial seasonal variation in SOA formation upon OFR aging; diurnally varying OA enhancements of ∼3-8 μg m-3 were observed in summer and significantly lower enhancements (∼0.5-1 μg m-3) in winter. Measurements in both seasons showed consistent changes in bulk OA properties (chemical composition; volatility) with OFR aging. Mild increases in traffic-related SOA precursors during summer partly explains the seasonal variation. However, biogenic emissions, with sharp temperature dependence, appear to dominate summer OFR-SOA. Our analysis indicates that SOA observed in the OFR is similar (within a factor of 2) to that predicted to form from traffic and biogenic precursors using literature yields, especially in winter. This study highlights the utility of the OFR for studying the prevalence of SOA precursors in complex real-world settings.}, number={13}, journal={ENVIRONMENTAL SCIENCE & TECHNOLOGY}, publisher={American Chemical Society (ACS)}, author={Saha, Provat K. and Reece, Stephen M. and Grieshop, Andrew P.}, year={2018}, month={Jul}, pages={7192–7202} }
 @article{li_dallmann_may_stanier_grieshop_lipsky_robinson_presto_2018, title={Size distribution of vehicle emitted primary particles measured in a traffic tunnel}, volume={191}, ISSN={["1873-2844"]}, DOI={10.1016/j.atmosenv.2018.07.052}, abstractNote={Total and size-resolved concentrations and emission factors are used to compare fleet-averaged vehicle emissions in Pittsburgh, PA in 2002 and 2014. Winter-time traffic tunnel measurements acquired using dual scanning mobility particle sizers (SMPS) over the size range 3–500 nm form the key input for the analysis. Size-resolved mass emission factors were calculated assuming a nanoparticle aggregate model. The ultrafine particle (<30 nm) emissions of diesel vehicles significantly dropped from 2002 to 2014. In the 2014 study, a thermodenuder (TD) was deployed together with the SMPS to measure emissions of non-volatile particles. After evaporation at 250 °C inside the TD, the median diameter of the number-size distribution shifted from 16 nm to ∼7 nm. The total particle number decreased significantly (69%) after evaporating inside the TD, indicating that vehicle emitted particles may be largely externally mixed and that a large fraction of these particles may be purely composed of volatile components. Based on the SMPS-TD measurements, we report a size-resolved volatile-to-non-volatile-component-ratio for vehicle emitted particles. It shows that smaller particles (10–60 nm) emitted by vehicles are dominantly (over 75%) composed of volatile components. We also apportioned the size-resolved particles and non-volatile particle mass and number emission factors for both gasoline and diesel vehicles. Diesel vehicles emitted significantly more ultrafine particles and non-volatile particles than gasoline vehicles.}, journal={ATMOSPHERIC ENVIRONMENT}, author={Li, Xiang and Dallmann, Timothy R. and May, Andrew A. and Stanier, Charles O. and Grieshop, Andrew P. and Lipsky, Eric M. and Robinson, Allen L. and Presto, Albert A.}, year={2018}, month={Oct}, pages={9–18} }
 @article{saha_khlystov_grieshop_2017, title={Downwind evolution of the volatility and mixing state of near-road aerosols near a US interstate highway}, volume={8}, url={https://doi.org/10.5194/acp-2017-690}, DOI={10.5194/acp-2017-690}, abstractNote={Abstract. We present spatial measurements of particle volatility and mixing state at a site near a North Carolina interstate highway (I-40) applying several heating (thermodenuder; TD) experimental approaches. Measurements were conducted in summer 2015 and winter 2016 in a roadside trailer (10 m from road edge) and during downwind transects at different distances from the highway under favorable wind conditions using a mobile platform. Results show that the relative abundance of semi-volatile species (SVOCs) in ultrafine particles decreases with downwind distance, consistent with the dilution and mixing of traffic-sourced particles with background air and evaporation of semi-volatile species during downwind transport. An evaporation kinetics model was used to derive particle volatility distributions by fitting TD data. While the TD-derived distribution apportions about 20–30 % of particle mass as semi-volatile (SVOCs; effective saturation concentration, C* ≥ 1µm−3) at 10 m from road edge, approximately 10 % of particle mass is attributed to SVOCs at 220 m, showing that the particle-phase semi-volatile fraction decreases with downwind distance. The relative abundance of semi-volatile material in the particle-phase increased during winter. Downwind spatial gradients of the less-volatile particle fraction (that remaining after heating at 180 °C) was strongly correlated with black carbon (BC). BC size distribution and mixing state measured using a Single Particle Soot Photometer (SP2) at the roadside trailer showed that a large fraction (70–80 %) of BC particles were externally-mixed. Heating experiments with a volatility tandem differential mobility analyzer (V-TDMA) also showed that the non-volatile fraction in roadside aerosols are mostly externally mixed. V-TDMA measurements at different distances downwind from the highway indicate that mixing state of roadside aerosols does not change significantly (e.g., BC mostly remains externally mixed) within a few hundred meters from the highway. A preliminary analysis indicates that a super-position of volatility distributions measured in laboratory vehicle tests and of ``background'' aerosol can be used to represent the observed partitioning of near-road particles. The results from this study highlight that exposures and impacts of BC and semi-volatile organics containing particles in a near-road microenvironment may differ across seasons and under changing ambient conditions.
                        }, publisher={Copernicus GmbH}, author={Saha, Provat Kumar and Khlystov, Andrey and Grieshop, Andrew Patrick}, year={2017}, month={Aug} }
 @article{grieshop_jain_sethuraman_marshall_2017, title={Emission factors of health- and climate-relevant pollutants measured in home during a carbon-finance-approved cookstove intervention in rural India}, volume={1}, ISSN={2471-1403}, url={http://dx.doi.org/10.1002/2017gh000066}, DOI={10.1002/2017gh000066}, abstractNote={Abstract}, number={5}, journal={GeoHealth}, publisher={American Geophysical Union (AGU)}, author={Grieshop, Andrew P. and Jain, Grishma and Sethuraman, Karthik and Marshall, Julian D.}, year={2017}, month={Jul}, pages={222–236} }
 @article{wathore_mortimer_grieshop_2017, title={In-Use Emissions and Estimated Impacts of Traditional, Natural- and Forced-Draft Cookstoves in Rural Malawi}, volume={51}, ISSN={["1520-5851"]}, url={https://doi.org/10.1021/acs.est.6b05557}, DOI={10.1021/acs.est.6b05557}, abstractNote={Emissions from traditional cooking practices in low- and middle-income countries have detrimental health and climate effects; cleaner-burning cookstoves may provide “co-benefits”. Here we assess this potential via in-home measurements of fuel-use and emissions and real-time optical properties of pollutants from traditional and alternative cookstoves in rural Malawi. Alternative cookstove models were distributed by existing initiatives and include a low-cost ceramic model, two forced-draft cookstoves (FDCS; Philips HD4012LS and ACE-1), and three institutional cookstoves. Among household cookstoves, emission factors (EF; g (kg wood)−1) were lowest for the Philips, with statistically significant reductions relative to baseline of 45% and 47% for fine particulate matter (PM2.5) and carbon monoxide (CO), respectively. The Philips was the only cookstove tested that showed significant reductions in elemental carbon (EC) emission rate. Estimated health and climate cobenefits of alternative cookstoves were smaller than predicted from laboratory tests due to the effects of real-world conditions including fuel variability and nonideal operation. For example, estimated daily PM intake and field-measurement-based global warming commitment (GWC) for the Philips FDCS were a factor of 8.6 and 2.8 times higher, respectively, than those based on lab measurements. In-field measurements provide an assessment of alternative cookstoves under real-world conditions and as such likely provide more realistic estimates of their potential health and climate benefits than laboratory tests.}, number={3}, journal={ENVIRONMENTAL SCIENCE & TECHNOLOGY}, publisher={American Chemical Society (ACS)}, author={Wathore, Roshan and Mortimer, Kevin and Grieshop, Andrew P.}, year={2017}, month={Feb}, pages={1929–1938} }
 @article{reece_sinha_grieshop_2017, title={Primary and Photochemically Aged Aerosol Emissions from Biomass Cookstoves: Chemical and Physical Characterization}, volume={51}, ISSN={0013-936X 1520-5851}, url={http://dx.doi.org/10.1021/acs.est.7b01881}, DOI={10.1021/acs.est.7b01881}, abstractNote={Secondary organic aerosol (SOA) formation during photo-oxidation of primary emissions from cookstoves used in developing countries may make important contributions to their climate and air quality impacts. We present results from laboratory experiments with a field portable oxidation flow reactor (F-OFR) to study the evolution of emissions over hours to weeks of equivalent atmospheric aging. Lab tests, using dry red oak, measured fresh and aged emissions from a 3 stone fire (TSF), a "rocket" natural draft stove (NDS), and a forced draft gasifier stove (FDGS), in order of increasing modified combustion efficiency (MCE) and decreasing particulate matter emission factors (EF). SOA production was observed for all stoves/tests; organic aerosol (OA) enhancement factor ranged from 1.2 to 3.1, decreasing with increased MCE. In primary emissions, OA mass spectral fragments associated with oxygenated species (primary biomass burning markers) increased (decreased) with MCE; fresh OA from FDGS combustion was especially oxygenated. OA oxygenation increased with further oxidation for all stove emissions, even where minimal enhancement was observed. More efficient stoves emit particles with greater net direct specific warming than TSFs, with the difference increasing with aging. Our results show that the properties and evolution of cookstove emissions are a strong function of combustion efficiency and atmospheric aging.}, number={16}, journal={Environmental Science & Technology}, publisher={American Chemical Society (ACS)}, author={Reece, Stephen M. and Sinha, Aditya and Grieshop, Andrew P.}, year={2017}, month={Jul}, pages={9379–9390} }
 @article{saha_khlystov_yahya_zhang_xu_ng_grieshop_2017, title={Quantifying the volatility of organic aerosol in the southeastern US}, volume={17}, url={https://doi.org/10.5194/acp-17-501-2017}, DOI={10.5194/acp-17-501-2017}, abstractNote={Abstract. The volatility of organic aerosols (OA) has emerged as a property of primary importance in understanding their atmospheric life cycle, and thus abundance and transport. However, quantitative estimates of the thermodynamic (volatility, water solubility) and kinetic parameters dictating ambient-OA gas-particle partitioning, such as saturation concentrations (C∗), enthalpy of evaporation (ΔHvap), and evaporation coefficient (γe), are highly uncertain. Here, we present measurements of ambient-OA volatility at two sites in the southeastern US, one at a rural setting in Alabama dominated by biogenic volatile organic compounds (BVOCs) as part of the Southern Oxidant and Aerosol Study (SOAS) in June–July 2013, and another at a more anthropogenically influenced urban location in North Carolina during October–November 2013. These measurements applied a dual-thermodenuder (TD) system, in which temperature and residence times are varied in parallel to constrain equilibrium and kinetic aerosol volatility properties. Gas-particle partitioning parameters were determined via evaporation kinetic model fits to the dual-TD observations. OA volatility parameter values derived from both datasets were similar despite the fact that measurements were collected in distinct settings and seasons. The OA volatility distributions also did not vary dramatically over the campaign period or strongly correlate with OA components identified via positive matrix factorization of aerosol mass spectrometer data. A large portion (40–70 %) of measured ambient OA at both sites was composed of very-low-volatility organics (C∗ ≤ 0.1 µg m−3). An effective ΔHvap of bulk OA of ∼ 80–100 kJ mol−1 and a γe value of ∼ 0.5 best describe the evaporation observed in the TDs. This range of ΔHvap values is substantially higher than that typically assumed for simulating OA in atmospheric models (30–40 kJ mol−1). TD data indicate that γe is on the order of 0.1 to 0.5, indicating that repartitioning timescales for atmospheric OA are on the order of several minutes to an hour under atmospheric conditions. The OA volatility distributions resulting from fits were compared to those simulated in the Weather, Research and Forecasting model with Chemistry (WRF/Chem) with a current treatment of secondary organic aerosol (SOA) formation. The substantial fraction of low-volatility material observed in our measurements is largely missing from simulations, and OA mass concentrations are underestimated. The large discrepancies between simulations and observations indicate a need to treat low-volatility OA in atmospheric models. Volatility parameters extracted from ambient measurements enable evaluation of emerging treatments for OA (e.g., secondary OA using the volatility basis set or formed via aqueous chemistry) in atmospheric models.
                    }, number={1}, journal={Atmospheric Chemistry and Physics}, publisher={Copernicus GmbH}, author={Saha, Provat K. and Khlystov, Andrey and Yahya, Khairunnisa and Zhang, Yang and Xu, Lu and Ng, Nga L. and Grieshop, Andrew P.}, year={2017}, month={Jan}, pages={501–520} }
 @article{grieshop_2017, title={Review of Sato et al.}, volume={11}, url={https://doi.org/10.5194/acp-2017-860-RC2}, DOI={10.5194/acp-2017-860-RC2}, abstractNote={This paper presents results from a series of chamber experiments in which a-pinene was oxidized with ozone and OH and the resulting aerosol measured in-situ and via measurements of particulate matter.A-pinene ozonolysis is a well-studied system, but a number of open questions remain, with the product distribution (typically quanti- C1Printer-friendly version Discussion paper ration kinetics and phase of laboratory and ambient secondary organic aerosol."Proceedings of the National Academy of Sciences.}, publisher={Copernicus GmbH}, author={Grieshop, Andrew}, year={2017}, month={Nov} }
 @article{saha_khlystov_grieshop_2017, title={Supplementary material to &quot;Downwind evolution of the volatility and mixing state of near-road aerosols near a US interstate highway&quot;}, volume={8}, url={https://doi.org/10.5194/acp-2017-690-supplement}, DOI={10.5194/acp-2017-690-supplement}, publisher={Copernicus GmbH}, author={Saha, Provat Kumar and Khlystov, Andrey and Grieshop, Andrew Patrick}, year={2017}, month={Aug} }
 @article{saha_grieshop_2016, title={Exploring Divergent Volatility Properties from Yield and Thermodenuder Measurements of Secondary Organic Aerosol from alpha-Pinene Ozonolysis}, volume={50}, ISSN={["1520-5851"]}, DOI={10.1021/acs.est.6b00303}, abstractNote={There are large uncertainties in the parameters dictating the gas-particle partitioning of secondary organic aerosols (SOA), although this process has major influences on their atmospheric lifecycle. Here, we extract parameters that describe the partitioning of SOA from α-pinene ozonolysis using measurements from a dual-thermodenuder (TD) system that constrains both the equilibrium and the kinetic properties that dictate SOA phase partitioning. Parallel TDs that vary in temperature and residence time were used with an evaporation-kinetics model to extract parameter values. An evaporation coefficient of an order of 0.1 best describes the observed evaporation, suggesting equilibration time scales of atmospheric SOA on the order of minutes to hours. A total of 20-40% of SOA mass consists of low-volatility material (saturation concentration of <0.3 μg m(-3)) in the TD-derived SOA volatility distribution. While distinct from existing parametrizations from aerosol growth experiments, derived values are consistent with recent observations of slow room-temperature evaporation of SOA and contributions from extremely low volatility organic compounds formed during α-pinene ozonolysis. The volatility parameters thus determined suggest that SOA yields and enthalpies of evaporation are substantially higher, and products less volatile, than is currently assumed in atmospheric models. These results will help improve the representation of SOA in air-quality and climate models.}, number={11}, journal={ENVIRONMENTAL SCIENCE & TECHNOLOGY}, author={Saha, Provat K. and Grieshop, Andrew P.}, year={2016}, month={Jun}, pages={5740–5749} }
 @article{aung_jain_sethuraman_baumgartner_reynolds_grieshop_marshall_brauer_2016, title={Health and Climate-Relevant Pollutant Concentrations from a Carbon-Finance Approved Cookstove Intervention in Rural India}, volume={50}, ISSN={["1520-5851"]}, DOI={10.1021/acs.est.5b06208}, abstractNote={Efforts to introduce more efficient stoves increasingly leverage carbon-finance to scale up dissemination of interventions. We conducted a randomized intervention study to evaluate a Clean Development Mechanism approved stove replacement impact on fuelwood usage, and climate and health-relevant air pollutants. We randomly assigned 187 households to either receive the intervention or to continue using traditional stoves. Measurements of fine particulate matter (PM2.5) and absorbance were conducted in cooking areas, village center and at upwind background site. There were minor and overlapping seasonal differences (post- minus preintervention change) between control and intervention groups for median (95% CI) fuel use (-0.60 (-1.02, -0.22) vs -0.52 (-1.07, 0.00) kg day(-1)), and 24 h absorbance (35 (18, 60) vs 36 (22, 50) × 10(-6) m(-1)); for 24 h PM2.5, there was a higher (139 (61,229) vs 73(-6, 156) μg m(-3))) increase in control compared to intervention homes between the two seasons. Forty percent of the intervention homes continued using traditional stoves. For intervention homes, absorbance-to-mass ratios suggest a higher proportion of black carbon in PM2.5 emitted from intervention compared with traditional stoves. Absent of field-based evaluation, stove interventions may be pursued that fail to realize expected carbon reductions or anticipated health and climate cobenefits.}, number={13}, journal={ENVIRONMENTAL SCIENCE & TECHNOLOGY}, author={Aung, Ther W. and Jain, Grishma and Sethuraman, Karthik and Baumgartner, Jill and Reynolds, Conor and Grieshop, Andrew P. and Marshall, Julian D. and Brauer, Michael}, year={2016}, month={Jul}, pages={7228–7238} }
 @article{saha_khlystov_yahya_zhang_xu_ng_grieshop_2016, title={Quantifying the volatility of organic aerosol in the southeastern U.S.}, volume={8}, url={https://doi.org/10.5194/acp-2016-575}, DOI={10.5194/acp-2016-575}, abstractNote={Abstract. The volatility of organic aerosols (OA) has emerged as a property of primary importance in understanding their atmospheric lifecycle, and thus abundance and transport. However, quantitative estimates of the thermodynamic (volatility) and kinetic parameters dictating ambient OA gas-particle partitioning, such as saturation concentrations (C*), enthalpy of evaporation (ΔHvap) and evaporation coefficient (γe), are highly uncertain. Here, we present measurements of ambient OA volatility at two sites in the southeastern U.S., one at biogenic-volatile-organic-compound (BVOC)-dominated rural setting in Alabama as part of the Southern Oxidant and Aerosol Study (SOAS) in June–July, 2013, and another at a more anthropogenically-influenced urban location in North Carolina during October–November, 2013. These measurements applied a dual-thermodenuder (TD) system, in which temperature and residence times are varied in parallel, to constrain equilibrium and kinetic aerosol volatility properties. Gas-particle partitioning parameters were determined via evaporation kinetic model fits to the dual-TD observations. OA volatility parameters values derived from both datasets were similar despite the fact that measurements were collected in distinct settings and seasons. The OA volatility distributions also did not vary dramatically over the campaign period nor strongly correlate with OA components identified via positive matrix factorization of aerosol mass spectrometer data. A large portion (40–70 %) of measured ambient OA at both sites was composed of very low volatility organics (C*≤ 0.1 μg m−3). An effective ΔHvap of bulk OA of ~ 80–100 kJ mol−1 and a γe value of ~ 0.5 best describe the evaporation observed in the TDs. This range of ΔHvap values is substantially higher than that typically assumed for simulating OA in atmospheric models (30–40 kJ mol−1). TD data indicate that γe is on the order of 0.1 to 0.5, indicating that repartitioning timescales for atmospheric OA are on the order of several minutes to an hour under atmospheric conditions. The OA volatility distributions resulting from fits were compared to those simulated in the Weather, Research and Forecasting model with Chemistry (WRF/Chem) with a current treatment of SOA formation. The substantial fraction of low-volatility material observed in our measurements is largely missing from simulations, and OA mass concentrations are underestimated. The large discrepancies between simulations and observations indicate a need to treat low volatility OA in atmospheric models. Volatility parameters extracted from ambient measurements enable evaluation of emerging treatments for OA (e.g., secondary OA using the volatility basis set or formed via aqueous chemistry) in atmospheric models.
                        }, publisher={Copernicus GmbH}, author={Saha, Provat K. and Khlystov, Andrey and Yahya, Khairunnisa and Zhang, Yang and Xu, Lu and Ng, Nga L. and Grieshop, Andrew P.}, year={2016}, month={Aug} }
 @article{saha_khlystov_yahya_zhang_xu_ng_grieshop_2016, title={Supplementary material to &quot;Quantifying the volatility of organic aerosol in the southeastern U.S.&quot;}, volume={8}, url={https://doi.org/10.5194/acp-2016-575-supplement}, DOI={10.5194/acp-2016-575-supplement}, abstractNote={Estimation of approximate equivalent OA MFR for VRT-TD}, publisher={Copernicus GmbH}, author={Saha, Provat K. and Khlystov, Andrey and Yahya, Khairunnisa and Zhang, Yang and Xu, Lu and Ng, Nga L. and Grieshop, Andrew P.}, year={2016}, month={Aug} }
 @article{saha_khlystov_grieshop_2015, title={Determining Aerosol Volatility Parameters Using a "Dual Thermodenuder" System: Application to Laboratory-Generated Organic Aerosols}, volume={49}, ISSN={["1521-7388"]}, DOI={10.1080/02786826.2015.1056769}, abstractNote={Thermodenuders (TD) are a tool widely used for measuring aerosol volatility in the laboratory and field. Extracting the parameters that dictate organic aerosol volatility from TD data is challenging because gas-particle partitioning rarely reaches equilibrium inside a TD operating under atmospheric conditions, thus a wide variety of parameter sets can explain observed evaporation. Component volatilities (as represented by saturation vapor pressure, Csat), cannot be directly extracted due to uncertainties in potential limitations to mass transfer (represented by mass accommodation coefficient, α) and components’ enthalpies of evaporation (ΔHvap). To address these limitations, we have developed a “dual TD” experimental approach in which one line uses a temperature-stepping TD (TS-TD) with a relatively long residence time (RT) and the other operates isothermally at variable residence time (VRT-TD). Data from this approach are used in tandem with an optimizing evaporation kinetics model to extract the values of parameters dictating volatility (Csat, and associated values of ΔHvap and α). The system was evaluated using laboratory generated dicarboxylic acid aerosols (adipic acid and succinic acid). Excellent agreement with previously published evaporation data collected with other TD systems was observed. Parameter values reported in the literature for the tested acids vary widely, but our results are generally consistent with those from studies that allow for nonunity values of α. For example, our results suggest that α for these aerosols are of order 0.1, in agreement with results determined by Saleh et al. (2009, 2012). Modeling results suggest that the addition of VRT-TD data provides tighter constraint on feasible ΔHvap and α values. The dual TD approach presented here does not rely on equilibration in the TD and thus can be directly applied to extract volatility parameters for more complex laboratory and ambient organic aerosol systems. Copyright 2015 American Association for Aerosol Research}, number={8}, journal={AEROSOL SCIENCE AND TECHNOLOGY}, author={Saha, Provat K. and Khlystov, Andrey and Grieshop, Andrew P.}, year={2015}, month={Aug}, pages={620–632} }
 @article{park_rogak_grieshop_2013, title={A Two-Dimensional Laminar Flow Model for Thermodenuders Applied to Vapor Pressure Measurements}, volume={47}, ISSN={["1521-7388"]}, DOI={10.1080/02786826.2012.750711}, abstractNote={Thermodenuders (TD) have been used to quantify the volatility of aerosol species, frequently with the aid of modeling. Here we present a two-dimensional model of flow, heat transfer, and aerosol dynamics that is fast, yet includes spatial resolution of the complete aerosol size distribution. We first demonstrate the utility of the model by interpreting nonequilibrium TD measurement data previously reported in the literature. It is shown that the thermogram (temperature vs. mass fraction remaining) curve is remarkably insensitive to radial variations in temperature and vapor concentration under typical conditions. Therefore, the discrepancies among vapor pressure estimates determined in TD studies are unlikely to be due to oversimplified flow models, but are instead likely due to faulty assumptions concerning evaporation kinetics. We then show that the best-fit range for the parameters that dictate equilibrium partitioning (saturation vapor pressure at a reference temperature and enthalpy of vaporization) can also be obtained by fitting nonequilibrium TD data using a three-parameter model that accounts for mass transfer limitations (by also fitting the evaporation coefficient). The degree of agreement between experiments and model simulations are examined for two dicarboxylic acids using the model developed in this study. The best-fit parameters were within the uncertainty range previously found using an “equilibrated” TD approach for butanedioic acid, whereas significantly better model-experiment agreement was obtained for a much lower value of enthalpy of vaporization than previously reported for hexanedioic acid. Copyright 2013 American Association for Aerosol Research}, number={3}, journal={AEROSOL SCIENCE AND TECHNOLOGY}, author={Park, Sung Hoon and Rogak, Steven N. and Grieshop, Andrew P.}, year={2013}, month={Mar}, pages={283–293} }
 @article{lagally_reynolds_grieshop_kandlikar_rogak_2012, title={Carbon Nanotube and Fullerene Emissions from Spark-Ignited Engines}, volume={46}, ISSN={0278-6826 1521-7388}, url={http://dx.doi.org/10.1080/02786826.2011.617399}, DOI={10.1080/02786826.2011.617399}, abstractNote={Particles were collected from the exhaust of Indian autorickshaws with natural gas and gasoline-fueled spark-ignited engines. Transmission electron microscopy was used to determine the size and shape of 2121 systematically selected particles. Particles were largely soot agglomerates and other types documented in the literature, but approximately 10% of the nonvolatile particles were multiwalled carbon nanotubes and fullerenes, forms of crystalline carbon distinct from soot. Autorickshaw fullerenic particle number emissions can be above 1011 per kg of fuel consumed. The nanotubes identified from the exhaust of autorickshaws average 168 nm in length. This is shorter than those nanotubes of greatest health concern, but given the paucity of toxicological data on carbon nanotubes and fullerenes, the potential environmental abundance from engine sources warrants closer attention. In particular, a broader range of engine types should be considered. [Supplemental materials are available for this article. Please go to the publisher's online edition of Aerosol Science & Technology to view the online files.] Copyright 2012 American Association for Aerosol Research}, number={2}, journal={Aerosol Science and Technology}, publisher={Informa UK Limited}, author={Lagally, C. D. and Reynolds, C. C. O. and Grieshop, A. P. and Kandlikar, M. and Rogak, S. N.}, year={2012}, month={Feb}, pages={156–164} }
 @article{grieshop_boland_reynolds_gouge_apte_rogak_kandlikar_2012, title={Modeling air pollutant emissions from Indian auto-rickshaws: Model development and implications for fleet emission rate estimates}, volume={50}, ISSN={["1873-2844"]}, DOI={10.1016/j.atmosenv.2011.12.046}, abstractNote={Chassis dynamometer tests were conducted on 40 Indian auto-rickshaws with 3 different fuel–engine combinations operating on the Indian Drive Cycle (IDC). Second-by-second (1 Hz) data were collected and used to develop velocity-acceleration look-up table models for fuel consumption and emissions of CO2, CO, total hydrocarbons (THC), oxides of nitrogen (NOx) and fine particulate matter (PM2.5) for each fuel–engine combination. Models were constructed based on group-average vehicle activity and emissions data in order to represent the performance of a ‘typical’ vehicle. The models accurately estimated full-cycle emissions for most species, though pollutants with more variable emission rates (e.g., PM2.5) were associated with larger errors. Vehicle emissions data showed large variability for single vehicles (‘intra-vehicle variability’) and within the test group (‘inter-vehicle variability’), complicating the development of a single model to represent a vehicle population. To evaluate the impact of this variability, sensitivity analyses were conducted using vehicle activity data other than the IDC as model input. Inter-vehicle variability dominated the uncertainty in vehicle emission modeling. ‘Leave-one-out’ analyses indicated that the model outputs were relatively insensitive to the specific sample of vehicles and that the vehicle samples were likely a reasonable representation of the Delhi fleet. Intra-vehicle variability in emissions was also substantial, though had a relatively minor impact on model performance. The models were used to assess whether the IDC, used for emission factor development in India, accurately represents emissions from on-road driving. Modeling based on Global Positioning System (GPS) activity data from real-world auto-rickshaws suggests that, relative to on-road vehicles in Delhi, the IDC systematically under-estimates fuel use and emissions; real-word auto-rickshaws consume 15% more fuel and emit 49% more THC and 16% more PM2.5. The models developed in this study can be used to further explore the impact of varying vehicle activity patterns on emissions in efforts to manage air quality and mitigate air pollution exposure and air pollution related health impacts.}, journal={ATMOSPHERIC ENVIRONMENT}, author={Grieshop, Andrew P. and Boland, Daniel and Reynolds, Conor C. O. and Gouge, Brian and Apte, Joshua S. and Rogak, Steven N. and Kandlikar, Milind}, year={2012}, month={Apr}, pages={148–156} }
 @article{reynolds_grieshop_kandlikar_2011, title={Climate and Health Relevant Emissions from in-Use Indian Three-Wheelers Fueled by Natural Gas and Gasoline}, volume={45}, ISSN={0013-936X 1520-5851}, url={http://dx.doi.org/10.1021/es102430p}, DOI={10.1021/es102430p}, abstractNote={Auto-rickshaws in India use different fuels and engine technologies, with varying emissions and implications for air quality and climate change. Chassis dynamometer emission testing was conducted on 30 in-use auto-rickshaws to quantify the impact of switching from gasoline to compressed natural gas (CNG) in spark-ignition engines. Thirteen test vehicles had two-stroke CNG engines (CNG-2S) and 17 had four-stroke CNG engines (CNG-4S), of which 11 were dual-fuel and operable on a back-up gasoline (petrol) system (PET-4S). Fuel-based emission factors were determined for gaseous pollutants (CO(2), CH(4), NO(X), THC, and CO) and fine particulate matter (PM(2.5)). Intervehicle variability was high, and for most pollutants there was no significant difference (95% confidence level) between "old" (1998-2001) and "new" (2007-2009) age-groups within a given fuel-technology class. Mean fuel-based PM(2.5) emission factor (mean (95% confidence interval)) for CNG-2S (14.2 g kg(-1) (6.2-26.7)) was almost 30 times higher than for CNG-4S (0.5 g kg(-1) (0.3-0.9)) and 12 times higher than for PET-4S (1.2 g kg(-1) (0.8-1.7)). Global warming commitment associated with emissions from CNG-2S was more than twice that from CNG-4S or PET-4S, due mostly to CH(4) emissions. Comprehensive measurements and data should drive policy interventions rather than assumptions about the impacts of clean fuels.}, number={6}, journal={Environmental Science & Technology}, publisher={American Chemical Society (ACS)}, author={Reynolds, Conor C. O. and Grieshop, Andrew P. and Kandlikar, Milind}, year={2011}, month={Mar}, pages={2406–2412} }
 @article{grieshop_marshall_kandlikar_2011, title={Health and climate benefits of cookstove replacement options}, volume={39}, ISSN={0301-4215}, url={http://dx.doi.org/10.1016/j.enpol.2011.03.024}, DOI={10.1016/j.enpol.2011.03.024}, abstractNote={The health and climate impacts of available household cooking options in developing countries vary sharply. Here, we analyze and compare these impacts (health; climate) and the potential co-benefits from the use of fuel and stove combinations. Our results indicate that health and climate impacts span 2 orders of magnitude among the technologies considered. Indoor air pollution is heavily impacted by combustion performance and ventilation; climate impacts are influenced by combustion performance and fuel properties including biomass renewability. Emission components not included in current carbon trading schemes, such as black carbon particles and carbon monoxide, can contribute a large proportion of the total climate impact. Multiple ‘improved’ stove options analyzed in this paper yield roughly equivalent climate benefits but have different impacts on indoor air pollution. Improvements to biomass stoves can improve indoor air quality, which nonetheless remains significantly higher than for stoves that use liquid or gaseous hydrocarbons. LPG- and kerosene-fueled stoves have unrivaled air quality benefits and their climate impacts are also lower than all but the cleanest stoves using renewable biomass.}, number={12}, journal={Energy Policy}, publisher={Elsevier BV}, author={Grieshop, Andrew P. and Marshall, Julian D. and Kandlikar, Milind}, year={2011}, month={Dec}, pages={7530–7542} }
 @book{zusman_srinivasan_dhakal_2011, place={London}, title={Low Carbon Transport in Asia: Strategies for Optimizing Co-benefits}, ISBN={9780203153833}, url={http://dx.doi.org/10.4324/9780203153833}, DOI={10.4324/9780203153833}, abstractNote={Foreword. Hironori Hamanaka Preface. Michael P. Walsh 1. Low Carbon Transport and Co-benefits in Asia: An Overview Eric Zusman, Ancha Srinivasan and Shobhakar Dhakal 2. The Co-benefits of Transport Policies in Asia: A Review of the Literature Diego Silva Herran, Naoko Matsumoto 3. Maximizing the Co-benefits of Light-Duty Dieselization in Asia Ray Minjares, Dan Rutherford 4. Reducing Particulate Matter Emissions from Buses and Trucks in Asia: A Framework to Assess Air Pollution and Climate Change Co-Impacts Conor C.O. Reynolds, Andrew P. Grieshop, and Milind Kandlikar 5. Quantifying Co-benefits from Low Carbon Transport in Hanoi, Vietnam Lee Schipper, Wei-Shieun Ng, Le Anh Tuan, and Hans Oern 6. Analyzing the Co-benefits of Transport Policies in Hyderabad, India Sarath Guttikunda, Ramani Kopakka 7. The Co-Benefits of a City Toll in Beijing: Barriers and Solutions Felix Creutzig, Alainna Thomas, Daniel M. Kammen and Elizabeth Deakin 8. Integrating Land Use, Transport, Energy and the Environment: The Case of Bandung, Indonesia Ranjith Perera, Ariva Sugandi Permana 9. Enabling Fuel Switching Pakistan: A Case Study of Compressed Natural Gas Hilal A. Raza, Syed Safdar Zaheer, and Nasreen Farah 10. The Co-benefits of Jakarta's Bus Rapid Transit (BRT): Getting the Institutions Right Heru Sutomo, Jane Romero, and Eric Zusman 11. Japan's Approach to Co-benefits: Recognition, Implementation, and Evaluation Kazuhiko Takemoto, Tokuya Wada, and Hirofumi Aizawa 12. International Climate Change Initiatives and Low Carbon Transport in Asia: Perspectives and Prospects Cornie Huizenga 13. The Way Forward}, publisher={Routledge}, year={2011} }
 @book{kandlikar_reynolds_grieshop_2010, place={Frederiksberg, Denmark}, title={A Perspective Paper on Black Carbon Mitigation as a Response to Climate Change}, institution={Copenhagen Consensus Center}, author={Kandlikar, M. and Reynolds, C.C.O. and Grieshop, A.P.}, year={2010} }
 @article{robinson_grieshop_donahue_hunt_2010, title={Updating the Conceptual Model for Fine Particle Mass Emissions from Combustion Systems}, volume={60}, ISSN={1096-2247 2162-2906}, url={http://dx.doi.org/10.3155/1047-3289.60.10.1204}, DOI={10.3155/1047-3289.60.10.1204}, abstractNote={Abstract Atmospheric transformations determine the contribution of emissions from combustion systems to fine particulate matter (PM) mass. For example, combustion systems emit vapors that condense onto existing particles or form new particles as the emissions are cooled and diluted. Upon entering the atmosphere, emissions are exposed to atmospheric oxidants and sunlight, which causes them to evolve chemically and physically, generating secondary PM. This review discusses these transformations, focusing on organic PM. Organic PM emissions are semi -volatile at atmospheric conditions and thus their partitioning varies continuously with changing temperature and concentration. Because organics contribute a large portion of the PM mass emitted by most combustion sources, these emissions cannot be represented using a traditional, static emission factor. Instead, knowledge of the volatility distribution of emissions is required to explicitly account for changes in gas-particle partitioning. This requires updating how PM emissions from combustion systems are measured and simulated from combustion systems. Secondary PM production often greatly exceeds the direct or primary PM emissions; therefore, secondary PM must be included in any assessment of the contribution of combustion systems to ambient PM concentrations. Low-volatility organic vapors emitted by combustion systems appear to be very important secondary PM precursors that are poorly accounted for in inventories and models. The review concludes by discussing the implications that the dynamic nature of these PM emissions have on source testing for emission inventory development and regulatory purposes. This discussion highlights important linkages between primary and secondary PM, which could lead to simplified certification test procedures while capturing the emission components that contribute most to atmospheric PM mass.}, number={10}, journal={Journal of the Air & Waste Management Association}, publisher={Informa UK Limited}, author={Robinson, Allen L. and Grieshop, Andrew P. and Donahue, Neil M. and Hunt, Sherri W.}, year={2010}, month={Oct}, pages={1204–1222} }
 @article{grieshop_reynolds_kandlikar_dowlatabadi_2009, title={A black-carbon mitigation wedge}, volume={2}, ISSN={1752-0894 1752-0908}, url={http://dx.doi.org/10.1038/ngeo595}, DOI={10.1038/ngeo595}, number={8}, journal={Nature Geoscience}, publisher={Springer Science and Business Media LLC}, author={Grieshop, Andrew P. and Reynolds, Conor C. O. and Kandlikar, Milind and Dowlatabadi, Hadi}, year={2009}, month={Aug}, pages={533–534} }
 @inbook{baron_lomborg_david montgomery_tuladhar_kandlikar_reynolds_andrew_lomborg_2009, place={Cambridge}, title={Black Carbon Mitigation}, DOI={10.1017/CBO9780511779015.005}, abstractNote={Much attention has been given to mitigation policies designed to limit the emissions of carbon dioxide (CO2) and other greenhouse gases (GHGs) that contribute to atmospheric warming. However, it is generally agreed that as much as 40% of current net warming (10–20% of gross warming) is attributable to black carbon (Jacobsen 2007: 3). Because of its large effect on radiative forcing and relatively short residence time in the atmosphere, black carbon presents some unique opportunities for postponing the effects of climate change. Whereas CO2 has a lifetime of up to about forty years, black carbon remains in the atmosphere for as little as several weeks. As such, reducing emissions of black carbon can have an immediate near-term impact on atmospheric warming. Furthermore, since black carbon is considered responsible for about 30% of the Arctic melting, black carbon emission reductions can rapidly reduce the rate at which Arctic ice is melting and avert associated consequences. Black carbon reduction policies can also result in large health benefits, especially to citizens of developing countries.}, publisher={Cambridge University Press}, author={Baron, R. and Lomborg, B. and David Montgomery, W. and Tuladhar, S. and Kandlikar, M. and Reynolds, C. and Andrew, P. and Lomborg, B.}, year={2009} }
 @article{grieshop_miracolo_donahue_robinson_2009, title={Constraining the Volatility Distribution and Gas-Particle Partitioning of Combustion Aerosols Using Isothermal Dilution and Thermodenuder Measurements}, volume={43}, ISSN={0013-936X 1520-5851}, url={http://dx.doi.org/10.1021/es8032378}, DOI={10.1021/es8032378}, abstractNote={The gas-particle partitioning of primary organic aerosol (POA) emissions from a diesel engine and the combustion of hard- and soft-woods in a stove was investigated by isothermally diluting them in a smog chamber or by passing them through a thermodenuder and measuring the extent of evaporation. The experiments were conducted at atmospherically relevant conditions: low concentrations and small temperature perturbations. The partitioning of the POA emissions from both sources varied continuously with changing concentration and temperature. Although the POA emissions are semivolatile, they do not completely evaporate at typical atmospheric conditions. The overall partitioning characteristics of diesel and wood smoke POA are similar, with wood smoke being somewhat less volatile than the diesel exhaust. The gas-particle partitioning of aerosols formed from flash-vaporized engine lubricating oil was also studied; diesel POA is somewhat more volatile than the oil aerosol. The experimental data from the dilution- and thermodenuder-based techniques were fit using absorptive partitioning theory to derive a volatility distribution of the POA emissions from each source. These distributions are suitable for use in chemical transport models that simulate POA concentrations.}, number={13}, journal={Environmental Science & Technology}, publisher={American Chemical Society (ACS)}, author={Grieshop, Andrew P. and Miracolo, Marissa A. and Donahue, Neil M. and Robinson, Allen L.}, year={2009}, month={Jul}, pages={4750–4756} }
 @article{jimenez_canagaratna_donahue_prevot_zhang_kroll_decarlo_allan_coe_ng_et al._2009, title={Evolution of Organic Aerosols in the Atmosphere}, volume={326}, ISSN={0036-8075 1095-9203}, url={http://dx.doi.org/10.1126/science.1180353}, DOI={10.1126/science.1180353}, abstractNote={Framework for Change}, number={5959}, journal={Science}, publisher={American Association for the Advancement of Science (AAAS)}, author={Jimenez, J. L. and Canagaratna, M. R. and Donahue, N. M. and Prevot, A. S. H. and Zhang, Q. and Kroll, J. H. and DeCarlo, P. F. and Allan, J. D. and Coe, H. and Ng, N. L. and et al.}, year={2009}, month={Dec}, pages={1525–1529} }
 @article{grieshop_logue_donahue_robinson_2009, title={Laboratory investigation of photochemical oxidation of organic aerosol from wood fires 1: measurement and simulation of organic aerosol evolution}, volume={9}, ISSN={1680-7324}, url={http://dx.doi.org/10.5194/acp-9-1263-2009}, DOI={10.5194/acp-9-1263-2009}, abstractNote={Abstract. Experiments were conducted to investigate the effects of photo-oxidation on organic aerosol (OA) emissions from flaming and smoldering hard- and soft-wood fires under plume-like conditions. This was done by exposing the dilute emissions from a small wood stove to UV light in a smog chamber and measuring the gas- and particle-phase pollutant concentrations with a suite of instruments including a Proton Transfer Reaction Mass Spectrometer (PTR-MS), an Aerosol Mass Spectrometer (AMS) and a thermodenuder. The measurements highlight how atmospheric processing can lead to considerable evolution of the mass and volatility of biomass-burning OA. Photochemical oxidation produced substantial new OA, increasing concentrations by a factor of 1.5 to 2.8 after several hours of exposure to typical summertime hydroxyl radical (OH) concentrations. Less than 20% of this new OA could be explained using a state-of-the-art secondary organic aerosol model and the measured decay of traditional SOA precursors. The thermodenuder data indicate that the primary OA is semivolatile; at 50°C between 50 and 80% of the fresh primary OA evaporated. Aging reduced the volatility of the OA; at 50°C only 20 to 40% of aged OA evaporated. The predictions of a volatility basis-set model that explicitly tracks the partitioning and aging of low-volatility organics was compared to the chamber data. The OA production can be explained by the oxidation of low-volatility organic vapors; the model can also reproduce observed changes in OA volatility and composition. The model was used to investigate the competition between photochemical processing and dilution on OA concentrations in plumes.}, number={4}, journal={Atmospheric Chemistry and Physics}, publisher={Copernicus GmbH}, author={Grieshop, A. P. and Logue, J. M. and Donahue, N. M. and Robinson, A. L.}, year={2009}, month={Feb}, pages={1263–1277} }
 @article{grieshop_donahue_robinson_2009, title={Laboratory investigation of photochemical oxidation of organic aerosol from wood fires 2: analysis of aerosol mass spectrometer data}, volume={9}, ISSN={1680-7324}, url={http://dx.doi.org/10.5194/acp-9-2227-2009}, DOI={10.5194/acp-9-2227-2009}, abstractNote={Abstract. Experiments were conducted to investigate the effects of photo-oxidation on organic aerosol (OA) in dilute wood smoke by exposing emissions from soft- and hard-wood fires to UV light in a smog chamber. This paper focuses on changes in OA composition measured using a unit-mass-resolution quadrupole Aerosol Mass Spectrometer (AMS). The results highlight how photochemical processing can lead to considerable evolution of the mass, volatility and level of oxygenation of biomass-burning OA. Photochemical oxidation produced substantial new OA, more than doubling the OA mass after a few hours of aging under typical summertime conditions. Aging also decreased the volatility of the OA and made it progressively more oxygenated. The results also illustrate strengths of, and challenges with, using AMS data for source apportionment analysis. For example, the mass spectra of fresh and aged BBOA are distinct from fresh motor-vehicle emissions. The mass spectra of the secondary OA produced from aging wood smoke are very similar to those of the oxygenated OA (OOA) that dominates ambient AMS datasets, further reinforcing the connection between OOA and OA formed from photo-chemistry. In addition, aged wood smoke spectra are similar to those from OA created by photo-oxidizing dilute diesel exhaust. This demonstrates that the OOA observed in the atmosphere can be produced by photochemical aging of dilute emissions from different types of combustion systems operating on fuels with modern or fossil carbon. Since OOA is frequently the dominant component of ambient OA, the similarity of spectra of aged emissions from different sources represents an important challenge for AMS-based source apportionment studies.
                    }, number={6}, journal={Atmospheric Chemistry and Physics}, publisher={Copernicus GmbH}, author={Grieshop, A. P. and Donahue, N. M. and Robinson, A. L.}, year={2009}, month={Mar}, pages={2227–2240} }
 @article{grieshop_donahue_robinson_2007, title={Is the gas-particle partitioning in alpha-pinene secondary organic aerosol reversible?}, volume={34}, ISSN={0094-8276}, url={http://dx.doi.org/10.1029/2007GL029987}, DOI={10.1029/2007GL029987}, abstractNote={This paper discusses the reversibility of gas‐particle partitioning in secondary organic aerosol (SOA) formed from α‐pinene ozonolysis in a smog chamber. Previously, phase partitioning has been studied quantitatively via SOA production experiments and qualitatively by perturbing temperature and observing particle evaporation. In this work, two methods were used to isothermally dilute the SOA: an external dilution sampler and an in‐chamber technique. Dilution caused some evaporation of SOA, but repartitioning took place on a time scale of tens of minutes to hours–consistent with an uptake coefficient on the order of 0.001–0.01. However, given sufficient time, α‐pinene SOA repartitions reversibly based on comparisons with data from conventional SOA yield experiments. Further, aerosol mass spectrometer (AMS) data indicate that the composition of SOA varies with partitioning. These results suggest that oligomerization observed in high‐concentration laboratory experiments may be a reversible process and underscore the complexity of the kinetics of formation and evaporation of SOA.}, number={14}, journal={Geophysical Research Letters}, publisher={American Geophysical Union (AGU)}, author={Grieshop, Andrew P. and Donahue, Neil M. and Robinson, Allen L.}, year={2007}, month={Jul}, pages={11053} }
 @article{robinson_donahue_shrivastava_weitkamp_sage_grieshop_lane_pierce_pandis_2007, title={Rethinking Organic Aerosols: Semivolatile Emissions and Photochemical Aging}, volume={315}, ISSN={0036-8075 1095-9203}, url={http://dx.doi.org/10.1126/science.1133061}, DOI={10.1126/science.1133061}, abstractNote={Most primary organic-particulate emissions are semivolatile; thus, they partially evaporate with atmospheric dilution, creating substantial amounts of low-volatility gas-phase material. Laboratory experiments show that photo-oxidation of diesel emissions rapidly generates organic aerosol, greatly exceeding the contribution from known secondary organic-aerosol precursors. We attribute this unexplained secondary organic-aerosol production to the oxidation of low-volatility gas-phase species. Accounting for partitioning and photochemical processing of primary emissions creates a more regionally distributed aerosol and brings model predictions into better agreement with observations. Controlling organic particulate-matter concentrations will require substantial changes in the approaches that are currently used to measure and regulate emissions.}, number={5816}, journal={Science}, publisher={American Association for the Advancement of Science (AAAS)}, author={Robinson, A. L. and Donahue, N. M. and Shrivastava, M. K. and Weitkamp, E. A. and Sage, A. M. and Grieshop, A. P. and Lane, T. E. and Pierce, J. R. and Pandis, S. N.}, year={2007}, month={Mar}, pages={1259–1262} }
 @article{grieshop_lipsky_pekney_takahama_robinson_2006, title={Fine particle emission factors from vehicles in a highway tunnel: Effects of fleet composition and season}, volume={40}, ISSN={1352-2310}, url={http://dx.doi.org/10.1016/j.atmosenv.2006.03.064}, DOI={10.1016/j.atmosenv.2006.03.064}, abstractNote={In-use, fuel-based motor vehicle emission factors were determined using measurements made in a highway tunnel in Pittsburgh, Pennsylvania. Concentrations of PM2.5 mass, CO, CO2, and NOx were measured continuously. Filter-based measurements included PM2.5 mass, organic and elemental carbon (OC and EC), inorganic ions and metals. Fuel-based emission factors for each pollutant were calculated using a fuel-carbon balance. The weekday traffic volume and fleet composition varied in a consistent diurnal pattern with the estimated fraction of fuel consumed by heavy-duty diesel vehicle (HDDV) traffic ranging from 11% to 36%. The emission rate of most species showed a significant dependence on sample period. NOx, PM2.5, EC and OC emission factors were significantly larger during the early morning, truck-dominated period. Emissions of particulate metals associated with brake wear (Cu, Sb, Ba and potentially Ga) were emitted at higher rates during the rush-hour period, which is characterized by slower, stop-and-go traffic. Emission rates of crustal elements (Fe, Ca, Mg, Li), Zn and Mn were highest during the early-morning period when there was more heavy-truck traffic. A seasonal shift in average OC/EC ratio for the rush-hour period was observed; fall and summer OC/EC ratios are 1.0±0.6 and 0.26±0.06, respectively. Potential causes for this shift are increased partitioning of semi-volatile organic compounds into the gas phase during the summer months and/or effects of seasonal changes in fuel formulation. Emission factors for HDDV and light-duty vehicles (LDV) classes were estimated using a linear regression of emission factor as a function of fleet composition. The extrapolated emission factors generally agree with previously published measurements, though a substantial range in published values is noted.}, journal={Atmospheric Environment}, publisher={Elsevier BV}, author={Grieshop, Andrew P. and Lipsky, Eric M. and Pekney, Natalie J. and Takahama, Satoshi and Robinson, Allen L.}, year={2006}, pages={287–298} }
 @inproceedings{khounsary_hartman_heimann_macdowell_franck_grieshop_irick_padmore_1998, place={SPIE, San Diego, CA}, title={<title>Design, analysis, and performance of an epoxy-bonded bendable mirror</title>}, DOI={10.1117/12.331128}, abstractNote={The toroidal, silicon mirror on microdiffraction beamline 7.3.3 at the Advanced Light Source provides a 1:1 focus of the bend magnet source. The mirror is bent by two lead springs that are bolted to it through a pari of adhesive bonded end blocks. Because of the high loads that these adhesive joints must carry, three specific features of the bonds were tested: bondline geometry of the mating end blocks, surface preparation of the adherends, and strength of the adhesive. Bond strengths were evaluated by loading small test mirrors to failure using two epoxies under two different conditions of surface preparation - acid etching and simple UHV cleaning. In addition, the mirror's temperature distribution and figure errors were calculated with an Ansys Finite Element Model. The model's predictions were correlated to long trace profilometry as well as x-ray focus measurements.}, author={Khounsary, A. and Hartman, N. and Heimann, P. and MacDowell, A. and Franck, K. and Grieshop, A. and Irick, S. and Padmore, H.}, year={1998}, pages={40–51} }