Relationship between Atmospheric PM-Bound Reactive Oxygen Species, Their Half-Lives, and Regulated Pollutants: Investigation and Preliminary Model

Abstract

The concentration, nature, and persistence of particulate matter (PM)-bound reactive oxygen species (ROS) are of significant interest in understanding how atmospheric pollution affects health. However, the inherent difficulties in their measurement, particularly regarding the so-called "short-lived" ROS, have limited our understanding of their persistence and concentrations in the atmosphere. This paper aims to address this limitation through the analysis of PM-bound ROS measurements from the Particle Into Nitroxide Quencher (PINQ) system at an atmospheric monitoring site in the city of Heshan, Guangdong Province, China. The measured daily average and standard deviation for the measurement period was 0.050 ± 0.017 nmol• m −3 . The averaged measured concentration of ROS per mass of PM and standard deviation was 0.0012 ± nmol•mg. The dataset was also correlated with standard pollutants, and a simplified model was constructed to separate the contributions of short-lived (t 1/2 = 5 min) and long-lived (t 1/2 ∼ infinity) ROS to total concentration using ozone, carbon monoxide, and PM mass. This showed that the short-lived ROS contribute an average of 33% of the daily PMbound ROS burden over the measurement period, up to 52% of daily average on elevated days, and up to 71% for hourly averages. These results highlight the need for accurate measurements of short-lived ROS and provide the starting point for a general model to predict PM-bound ROS concentrations using widely available standard pollutants for future epidemiological research.

Robust quantification of the burst of OH radicals generated by ambient particles in nascent cloud droplets using a direct-to-reagent approach

“…Fuller et al (2014) observed a decrease by about a factor of five in ROS content of laboratory generated oxidized organic aerosols within the first 15 minutes of their being capturing on PTFE filters. Recently, Brown et al (2020) estimated up to 71% short-lived (defined as having a half-live of 5 mins or less) ROS to total hourly averaged PM-bound ROS at a site in the in Heshan, China. Zhang et al (2022) showed that on average more than 90% of ROS in a photochemically aged mixture of primary combustion soot particles and naphthalene or β-pinene aerosols were short-lived.…”

Particulate Oxidative Potential Associated with Fireworks Activity during Diwali at a site in the Indo-Gangetic Plain

“…Table 3 shows the correlation coe cient (r) between OPv (nmol min − 1 m − 3 ) and the trace gases (NO 2 , SO 2 , CO, O 3 ) (µg m − 3 ). Strong correlations (r 2 = 0.87) were observed with ozone during day-time, which functions both as an atmospheric oxidant and as a precursor to other important oxidants such as hydroxyl and nitrate radicals formed during photochemical processes and/or ozonolysis reactions (Brown et al 2020) and 60 µg m − 3 (NAAQS 2009)) to assess the toxicity of PM 2.5 . Figure 7 depicts the daily variance of the measured OPv and OPm, as well as the daily Hazard Index.…”

“…It's worth noting that a strong association between CO and OPv (r 2 = 0.47) was also detected during the day. These ndings could indicate that high-level organics in both the gas and particle phases of vehicular emissions are responsible for the generation of PM-bound ROS, as organics are oxidised via hydroxyl radical-initiated processes(Brown et al 2020). Pearson's correlation coe cients were also calculated to nd associations between OP and speci c components in PM 2.5 that contributed to DTT.…”

Preparation of Electrospun Active Molecules Membrane Application to Atmospheric Free Radicals

“…5 -bound ROS radicals, which can effectively trap radicals and can be used to study the relationship between PM 2 . 5 and the growth of ROS radicals [ 5 ]. Zhou J et al [ 6 ] measured ROS using 2,7-dichlorofluorescein diacetate (DCFH-DA) combined with a horseradish peroxide (HRP) catalyst.…”