@article{kumar_nde_guo_pathak_foley_ahmad_dangal_hasan_lard_aryal_et al._2025, title={A systematic review of environmentally persistent free radical (EPFR) formation, characteristics, and health effects: are there sufficient data for risk assessment?}, DOI={10.1080/10937404.2025.2602154}, abstractNote={Environmentally persistent free radicals (EPFRs) are stable free radicals formed on particulate matter (PM) through processes such as combustion and pyrolysis. These free radicals are generated on transition metal oxide surfaces in the presence of aromatic precursors. Exposure to EPFRs occurs primarily via inhalation of PM deriving from combustion, traffic, industrial activities, and both indoor and outdoor burning. Other environmental factors that might generate EPFRs are radon, electronic and tobacco cigarettes. EPFRs exhibit unexpectedly long half-lives, ranging from several weeks to, in some cases, several years. EPFRs may be carbon-centered, oxygen-centered or mixed, identified by g-values exhibited in electron paramagnetic resonance analysis. The radicals undergo redox cycling within aqueous solutions and in biological tissues/fluids triggering production of reactive oxygen species (ROS), comprised primarily of hydroxyl, superoxide, and peroxyl radicals. The stability of EPFRs, their association with PM<sub>2.5</sub>, and their ability to generate ROS may pose significant concerns for human health. To determine whether there are sufficient data for risk assessment, recent advances were examined in the following important aspects of EPFR research: (1) atmospheric chemistry, (2) human exposures, (3) animal toxicity, and (4) epidemiology. Our review found insufficient epidemiological and exposure studies; however, toxicological data in animals suggested that EPFR inhalation contributes to cardiovascular, respiratory, and metabolic diseases. Although EPFRs are not currently surveyed by a regulatory monitoring system, data indicate their widespread presence in the environment and their potential to initiate/exacerbate diseases.}, journal={Journal of Toxicology and Environmental Health Part B}, author={Kumar, Avinash and Nde, Divine and Guo, Chuqi and Pathak, Rashmi and Foley, Fox and Ahmad, Syed and Dangal, Prakash and Hasan, Farhana and Lard, Myron and Aryal, Ankit and et al.}, year={2025}, month={Dec} }
 @article{guo_ogunmusi_mathieu-campbell_lard_blanchard_khachatryan_vallee_subra_cormier_lomnicki_et al._2025, title={Spatial distribution of persistent components of particulate matter near a hazardous waste thermal treatment facility}, url={http://dx.doi.org/10.1016/j.envpol.2025.127524}, DOI={10.1016/j.envpol.2025.127524}, abstractNote={Open burn/open detonation (OB/OD) of hazardous waste poses serious environmental and public health risks. This community-engaged research study presents the first year-long, spatially resolved assessment of ambient air pollutant composition in Colfax, Louisiana - home to the last commercially operated OB/OD facility in the United States and situated in a rural and historically overburdened community. Until its permit changes took effect in December 2023, the facility processed military waste, fireworks, propellants, Superfund site soils, and other hazardous materials through OB/OD. These operations have long raised concerns among residents about air quality and associated health risks. To characterize pollutant distributions, we deployed two types of passive samplers and low-cost PurpleAir sensors to monitor PM<sub>2.5</sub>, environmentally persistent free radicals (EPFRs), and heavy metals at ten sites across four seasonal quarters from March 2022 through March 2023. Distinct PM<sub>2.5</sub> hotspots were observed near the facility, particularly during March to June and December to March. EPFRs exhibited the strongest spatial correlation with PM<sub>2.5</sub> from June to September. During September to December, elevated EPFR levels coincided with high concentrations of Cr and Ni. Al and Fe were the most abundant metals detected, with sites 6.3 and 6.7 km from the facility consistently showing elevated levels of Al, Ba, Fe, Mg, Mn, and EPFRs. Strong correlations were consistently observed among Al, Ba, Mg, and Mn throughout the year. These findings provide critical insight into the spatial and temporal behavior of airborne pollutants near OB/OD operations and highlight the effectiveness of passive sampling in complex, resource-limited field conditions.}, journal={Environmental Pollution}, author={Guo, Chuqi and Ogunmusi, Oluwafeyikemi and Mathieu-Campbell, Martine E. and Lard, Myron and Blanchard, Thomas and Khachatryan, Lavrent and Vallee, Brenda and Subra, Wilma and Cormier, Stephania A. and Lomnicki, Slawo and et al.}, year={2025}, month={Dec} }