Pollution characteristics and light-driven evolution of environmentally persistent free radicals in PM2.5 in two typical northern cities of China

Atmospheric evolution of environmentally persistent free radicals in rural North China Plain: insights into water solubility and effects on PM2.5 oxidative potential

“…Notably, higher EPFRv levels were observed in summer than in winter (Figure 1c), with the highest EPFRm occurring during summer (Figure 1d) in the studied area. This contrasts with findings from previous studies, which indicated that winter typically exhibits the highest EPFRv, especially for cities in northern China with prominent local emission sources of EPFRs, such as large-scale coal consumption (Wang et al, 2019;Jia et al, 2023;Ai et al, 2023). The distinct seasonal characteristic of EPFRs observed in our study could be attributed to the limited residential and industrial activities in rural NCP.…”

Toxicity Decreases with the Decay of Environmentally Persistent Free Radicals in Particulate Matter from Incomplete Solid Fuel Burning

“…9,10,12 Moreover, the lifespan of fast-decay EPFRs freshly emitted from solid fuel burning ranges from 15 to 97 h upon exposure to air (Figure 1b), which is one magnitude shorter than that of atmospheric PM 2.5 . 9,10,15 The brief lifespan of fast-decay EPFRs indicates heightened reactivity with O 2 .…”

“…Specifically, the average proportion of fast-decay EPFRs accounted for 40.5 ± 15.3% of the total EPFRs (20.6 ± 0.7% in wheat straw, 39.3 ± 0.6% in rice straw, 36.5 ± 1.2% in corn straw, 38.4 ± 0.7% in branches, and 67.9 ± 3.1% of the total EPFRs in bitumite) (Table S2). Differences in the proportions of fast-decay EPFRs might be attributed to variations in the solid fuel composition, pyrolysis temperature and burning products. ,, Possibly due to the depletion of reactive EPFRs when PM 2.5 is suspended in the atmosphere and interacts with O 2 , , the proportion of fast-decay EPFRs in PM 2.5 emitted from solid fuel burning is greater than that of atmospheric PM 2.5 (less than 20%). ,, Moreover, the lifespan of fast-decay EPFRs freshly emitted from solid fuel burning ranges from 15 to 97 h upon exposure to air (Figure b), which is one magnitude shorter than that of atmospheric PM 2.5 . ,, The brief lifespan of fast-decay EPFRs indicates heightened reactivity with O 2 .…”

“…Decay characteristics of particulate EPFRs freshly generated from wheat straw, branch and bitumite burning: (a) decline in EPFR spin density upon exposure to air; (b) comparison of the lifetimes of fast-decay EPFRs in PM 2.5 . C 0 and C in (a) represent the EPFR spin density at the initial stage and at specific time intervals, respectively, while the lifetimes of the fast-decay EPFRs of atmospheric PM 2.5 in (b) were adopted from previous studies. ,, …”

“…Environmentally persistent free radicals (EPFRs), characterized by incomplete electron distributions, dissipate upon reacting with O 2 and convert it into reactive oxygen species (ROS). − Thus, exposure to EPFRs bound in particulate matter (PM) can lead to adverse health effects, including DNA damage, pulmonary inflammation, and airway hyperresponsiveness. − The decay characteristics of EPFRs, which are related to their reactivity , and ability to catalyze ROS generation, are crucial. − The decay patterns of atmospheric EPFRs were investigated without a clear definition of the initial stage, − since reactive EPFRs in PM might already be quenched and regenerated during their suspension in the atmosphere. − Consequently, it is important to study EPFRs in PM freshly generated from primary sources.…”