@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}, abstractNote={We use air pollution exposure measurements and household survey data from four studies conducted across three countries in sub‐Saharan Africa (SSA) to analyze the association between carbon monoxide (CO) exposure from cooking with biomass and indicators of cognitive impairment. While there is strong evidence on the relationship between ambient air pollution exposure and cognitive impairment from studies in high‐income countries, relatively little research has focused on household air pollution (HAP) in low‐income country settings where risks of HAP exposure are high. This study is the first to our knowledge to focus on the association between HAP exposure (specifically CO exposure) and cognitive impairment across diverse settings in SSA. We use 24‐hour measurements of primary cooks’ exposure to CO across four study sites: urban Zambia ( n = 493); urban Malawi ( n = 130); rural Malawi ( n = 102); and urban Rwanda ( n = 2,576). We model the estimated percent carboxyhemoglobin (%COHb) of cooks and map values to a toxicological profile for risk of cognitive impairment. We find that across all study settings, cooks’ average %COHb levels are below levels of daily concern, but that cooks who use charcoal for preparing greater than 40% of meals are more likely to spend additional time at higher levels of risk. For the urban Zambia sample, we compare %COHb and frequency of charcoal use to a series of cognitive test scores and find no consistent relationships between %COHb and cognitive test scores. High levels of daily CO exposure from cooks across SSA highlight the potential for longer‐term negative cognitive (and other) health outcomes motivating additional research and efforts to characterize and mitigate risk.}, 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} }
 @misc{weyant_amoah_bittner_pedit_codjoe_jagger_2022, title={Occupational Exposure and Health in the Informal Sector: Fish Smoking in Coastal Ghana}, volume={130}, ISSN={["1552-9924"]}, DOI={10.1289/EHP9873}, abstractNote={Cheryl L. Weyant,1 Antwi-Boasiako Amoah,2,3 Ashley Bittner,4 Joe Pedit,5 Samuel Nii Ardey Codjoe,6 and Pamela Jagger1 School for Environment and Sustainability, University of Michigan, Ann Arbor, Michigan, USA Centre for Climate Change and Sustainability Studies, University of Ghana, Legon, Ghana Environmental Protection Agency (Ghana), Accra, Ghana Department of Civil, Construction, and Environmental Engineering, North Carolina State University, Raleigh, North Carolina, USA University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA Regional Institute for Population Studies, University of Ghana, Legon, Ghana}, number={1}, journal={ENVIRONMENTAL HEALTH PERSPECTIVES}, author={Weyant, Cheryl L. and Amoah, Antwi-Boasiako and Bittner, Ashley and Pedit, Joe and Codjoe, Samuel Nii Ardey and Jagger, Pamela}, year={2022}, month={Jan} }
 @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{polimera_kannappan_richardson_bittner_ferguson_moffett_eckert_bellovary_norris_2022, title={RESOLVE and ECO: Finding Low-metallicity z similar to 0 Dwarf AGN Candidates Using Optimized Emission-line Diagnostics}, volume={931}, ISSN={["1538-4357"]}, DOI={10.3847/1538-4357/ac6595}, abstractNote={Abstract
               Existing star-forming vs. active galactic nucleus (AGN) classification schemes using optical emission-line diagnostics mostly fail for low-metallicity and/or highly star-forming galaxies, missing AGN in typical z ∼ 0 dwarfs. To recover AGN in dwarfs with strong emission lines (SELs), we present a classification scheme optimizing the use of existing optical diagnostics. We use Sloan Digital Sky Survey emission-line catalogs overlapping the volume- and mass-limited REsolved Spectroscopy Of a Local VolumE (RESOLVE) and Environmental COntex (ECO) surveys to determine the AGN percentage in SEL dwarfs. Our photoionization grids show that the [O iii]/Hβ versus [S ii]/Hα diagram (S ii plot) and [O iii]/Hβ versus [O i]/Hα diagram (O i plot) are less metallicity sensitive and more successful in identifying dwarf AGN than the popular [O iii]/Hβ versus [N ii]/Hα diagnostic (N ii plot or “BPT diagram”). We identify a new category of “star-forming AGN” (SF-AGN) classified as star-forming by the N ii plot but as AGN by the S ii and/or O i plots. Including SF-AGN, we find the z ∼ 0 AGN percentage in dwarfs with SELs to be ∼3%–16%, far exceeding most previous optical estimates (∼1%). The large range in our dwarf AGN percentage reflects differences in spectral fitting methodologies between catalogs. The highly complete nature of RESOLVE and ECO allows us to normalize strong emission-line galaxy statistics to the full galaxy population, reducing the dwarf AGN percentage to ∼0.6%–3.0%. The newly identified SF-AGN are mostly gas-rich dwarfs with halo mass <1011.5
                  M
                  ⊙, where highly efficient cosmic gas accretion is expected. Almost all SF-AGN also have low metallicities (Z ≲ 0.4 Z
                  ⊙), demonstrating the advantage of our method.}, number={1}, journal={ASTROPHYSICAL JOURNAL}, author={Polimera, Mugdha S. and Kannappan, Sheila J. and Richardson, Chris T. and Bittner, Ashley S. and Ferguson, Carlynn and Moffett, Amanda J. and Eckert, Kathleen D. and Bellovary, Jillian M. and Norris, Mark A.}, year={2022}, month={May} }
 @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{palumbo_kannappan_frazer_eckert_norman_fraga_quint_amram_oliveira_bittner_et al._2020, title={Linking compact dwarf starburst galaxies in the RESOLVE survey to downsized blue nuggets}, volume={494}, ISSN={["1365-2966"]}, DOI={10.1093/mnras/staa899}, abstractNote={ABSTRACT
               We identify and characterize compact dwarf starburst (CDS) galaxies in the REsolved Spectroscopy Of a Local VolumE (RESOLVE) survey, a volume-limited census of galaxies in the local Universe, to probe whether this population contains any residual ‘blue nuggets,’ a class of intensely star-forming compact galaxies first identified at high redshift z. Our 50 low-z CDS galaxies are defined by dwarf masses (stellar mass M* < 109.5 M⊙), compact bulged-disc or spheroid-dominated morphologies (using a quantitative criterion, $\mu _\Delta \gt 8.6$), and specific star formation rates (SSFRs) above the defining threshold for high-z blue nuggets (log  SSFR [Gyr−1] > −0.5). Across redshifts, blue nuggets exhibit three defining properties: compactness relative to contemporaneous galaxies, abundant cold gas, and formation via compaction in mergers or colliding streams. Those with halo mass below Mhalo ∼ 1011.5 M⊙ may in theory evade permanent quenching and cyclically refuel until the present day. Selected only for compactness and starburst activity, our CDS galaxies generally have Mhalo ≲ 1011.5 M⊙ and gas-to-stellar mass ratio ≳1. Moreover, analysis of archival DECaLS photometry and new 3D spectroscopic observations for CDS galaxies reveals a high rate of photometric and kinematic disturbances suggestive of dwarf mergers. The SSFRs, surface mass densities, and number counts of CDS galaxies are compatible with theoretical and observational expectations for redshift evolution in blue nuggets. We argue that CDS galaxies represent a maximally starbursting subset of traditional compact dwarf classes such as blue compact dwarfs and blue E/S0s. We conclude that CDS galaxies represent a low-z tail of the blue nugget phenomenon formed via a moderated compaction channel that leaves open the possibility of disc regrowth and evolution into normal disc galaxies.}, number={4}, journal={MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY}, author={Palumbo, Michael L., III and Kannappan, Sheila J. and Frazer, Elaine M. and Eckert, Kathleen D. and Norman, Dara J. and Fraga, Luciano and Quint, Bruno C. and Amram, Philippe and Oliveira, Claudia Mendes and Bittner, Ashley S. and et al.}, year={2020}, month={Jun}, pages={4730–4750} }
 @article{richardson_polimera_kannappan_moffett_bittner_2019, title={Addressing the [O III]/H beta offset of dwarf galaxies in the RESOLVE survey}, volume={486}, ISSN={["1365-2966"]}, DOI={10.1093/mnras/stz1085}, abstractNote={Metal poor dwarf galaxies in the local universe, such as those found in the RESOLVE galaxy survey, often produce high [O III]/H\b{eta} ratios close to the star forming demarcation lines of the diagnostic BPT diagram. Modeling the emission from these galaxies at lower metallicities generally underpredicts this line ratio, which is typically attributed to a deficit of photons >35 eV. We show that applying a model that includes empirical abundances scaled with metallicity strongly influences the thermal balance in HII regions and preserves the [O III]/H\b{eta} offset even in the presence of a harder radiation field generated by interacting binaries. Additional heating mechanisms are more successful in addressing the offset. In accordance with the high sSFR typical of dwarf galaxies in the sample, we demonstrate that cosmic ray heating serves as one mechanism capable of aligning spectral synthesis predictions with observations. We also show that incorporating a range of physical conditions in our modeling can create even better agreement between model calculations and observed emission line ratios. Together these results emphasize that both the hardness of the incident continuum and the variety of physical conditions present in nebular gas clouds must be accurately accounted for prior to drawing conclusions from emission line diagnostic diagrams.}, number={3}, journal={MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY}, author={Richardson, Chris T. and Polimera, Mugdha S. and Kannappan, Sheila J. and Moffett, Amanda J. and Bittner, Ashley S.}, year={2019}, month={Jul}, pages={3541–3549} }