Size-resolved exposure risk of persistent free radicals (PFRs) in atmospheric aerosols and their potential sources

Abstract

<p><strong>Abstract.</strong> Environmentally persistent free radicals (EPFRs) are a new type of substance with potential health risks. EPFRs are widely present in atmospheric particulates, but there is a limited understanding of the size-resolved health risks of these radicals. This study first reported the exposure risks and source of EPFRs in atmospheric particulate matter (PM) of different particle sizes (< 10 μm) in Linfen, a typical coal-burning city in China. The type of EPFRs in fine particles (< 2.1 μm) is different from that in coarse particles (2.1–10 μm) in both winter and summer. However, the EPFR concentration is higher in coarse particles than in fine particles in summer, and the opposite trend is found in winter. In both seasons, combustion sources are the main sources of EPFRs with coal combustion as the major contributor in winter, while biomass combustion is the major source in summer. Dust contributes part of the EPFRs and it is mainly present in coarse particles in winter and the opposite in summer. The upper respiratory tract was found to be the area with the highest risk of exposure to EPFRs of the studied aerosols, with an exposure equivalent to that of approximately 21 cigarettes per person per day. Alveolar exposure to EPFRs is equivalent to 8 cigarettes per person per day, with combustion sources contributing the most to EPFRs in the alveoli. This study helps us to better understand the potential health risks of atmospheric PM with different particle sizes.</p>

Characteristics and Sources of Environmentally Persistent Free Radicals in PM2.5 in Dalian: Important Role of Polycyclic Aromatic Hydrocarbons

“…For example, Yang et al (2017b) detected the EPFRs in different size of ne particulate matter during haze days in winter in Beijing with concentration ranging from 1.49 to 1.95×10 20 spins/g, and found the particulate matter with aerodynamic diameters < 1 µm had a highest EPFRs level. Chen et al (2020) also found the level and type of EPFRs in ne particulate matter (< 2.1 µm) are different with those in coarse particles (2.1-10 µm). Other studies also found the EPFR levels in airborne particulate matter in different cities, such as Taif, Saudi Arabia, Denver, United States and Xuanwei, China (Runberg et al, 2020;Shaltout et al, 2015;Wang et al, 2018).…”

“…Missing values and uncertainty were input by the median concentration of the component and four times the median values to decrease their in uence on the results (Chen et al, 2020;Qian et al, 2020;.…”

“…Studies have shown that ambient particulate matters with different sizes could contain large amounts of EPFRs with different characteristics (Arangio et al, 2016;Chen et al, 2020;Shaltout et al, 2015;Yang et al, 2017b). For example, Yang et al (2017b) detected the EPFRs in different size of ne particulate matter during haze days in winter in Beijing with concentration ranging from 1.49 to 1.95×10 20 spins/g, and found the particulate matter with aerodynamic diameters < 1 µm had a highest EPFRs level.…”

Outdoor Health Risk of Atmospheric Particulate Matter at Night in Xi’an, Northwestern China

“…81−85 Therefore, herein, we also estimated the exposure risk by inhaling the equivalent number of cigarette tar EPFRs per day and night to assess the potential human risk (Figure 5g). 83,85,86 The results showed the seasonal average of EPFRs day/night in PM 10 and PM 2.5 exposure as winter: 1.66 ± 1.68; 1.33 ± 1.39; spring: 0.99 ± 1.06; 0.91 ± 1.42, whereas the average exposure amount of EPFRs per day and night in Xi'an were 1.24 and 1.37 cigarettes, which in total was equal to 452.6 and 500.05 cigarettes per year/ person. Compared to the study reported by Gehling and Dellinger, 2013a, 83 our results were five times higher.…”