Comparison of Oxidative Properties, Light Absorbance, and Total and Elemental Mass Concentration of Ambient PM _2.5 Collected at 20 European Sites

Abstract

ObjectiveIt has been proposed that the redox activity of particles may represent a major determinant of their toxicity. We measured the in vitro ability of ambient fine particles [particulate matter with aerodynamic diameters ≤2.5 μm (PM2.5)] to form hydroxyl radicals (•OH) in an oxidant environment, as well as to deplete physiologic antioxidants (ascorbic acid, glutathione) in the naturally reducing environment of the respiratory tract lining fluid (RTLF). The objective was to examine how these toxicologically relevant measures were related to other PM characteristics, such as total and elemental mass concentration and light absorbance.DesignGravimetric PM2.5 samples (n = 716) collected over 1 year from 20 centers participating in the European Community Respiratory Health Survey were available. Light absorbance of these filters was measured with reflectometry. PM suspensions were recovered from filters by vortexing and sonication before dilution to a standard concentration. The oxidative activity of these particle suspensions was then assessed by measuring their ability to generate •OH in the presence of hydrogen peroxide, using electron spin resonance and 5,5-dimethyl-1-pyrroline-N-oxide as spin trap, or by establishing their capacity to deplete antioxidants from a synthetic model of the RTLF.Results and ConclusionPM oxidative activity varied significantly among European sampling sites. Correlations between oxidative activity and all other characteristics of PM were low, both within centers (temporal correlation) and across communities (annual mean). Thus, no single surrogate measure of PM redox activity could be identified. Because these novel measures are suggested to reflect crucial biologic mechanisms of PM, their use may be pertinent in epidemiologic studies. Therefore, it is important to define the appropriate methods to determine oxidative activity of PM.

A rapid assessment of the impact of hazard reduction burning around Sydney, May 2016

“…Its possible importance for health is currently being discussed (Shiraiwa, Selzle & Pöschl, 2012). Initial studies on spatial and temporal variations of particle reactivity parameters have been conducted (Boogaard et al, 2012a;Künzli et al, 2006). Still missing is the link between particle reactivity and other particle characteristics, the actual mechanisms triggered, and the ageing and/or changes of particle reactivity during atmospheric transport due to chemical reactions.…”

Air pollution, oxidative stress and dietary supplementation: a review

“…It might be useful to measure the redox activity of ambient pollutants or the antioxidant depletion rates, as these may be the most relevant characteristics in the hypothesised pathways of redox imbalance. Various assays have been developed to measure the redox activity of particles, such as OH radical formation or antioxidant depletion rates [137]. However, the measurement methods may need further development to be applicable in epidemiological studies, in particular, for personal exposure assessment.…”

Inflammatory Cytokine Response to Ambient Particles Varies due to Field Collection Procedures

“…In this case, the measured activity could be adjusted upward to make it comparable to an ambient exposure experienced by the lung. Recent studies demonstrated differences in oxidative potential associated with PM collected in different European cities (17). Oxidative potential of PM also varied by traffic proximity within London and cities in The Netherlands (18,28).…”

“…There have been a few studies showing seasonal or broad spatial variability in PM proinflammatory or oxidant effects based on in vitro assessment of PM cellular response, or oxidative properties of PM (3,5,17,18). However, to our knowledge, the use of toxicological assays to assess spatial variability in long-term PM biological activity would be a new paradigm in exposure assessment for chronic effects epidemiology.…”