10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
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Relationship between Aerosol Composition and Sources and Their Oxidative Potential in Central Europe
KASPAR RUDOLF DÄLLENBACH, Gaëlle Uzu, Ivan Kourtchev, Laure-Estelle Cassagnes, Alexander Lucas Vogel, Giulia Stefenelli, Athanasia Vlachou, Jay G. Slowik, Jean-Luc Jaffrezo, Markus Kalberer, Josef Dommen, Urs Baltensperger, Imad El Haddad, Andre S.H. Prévôt, Paul Scherrer Institute / University of Helsinki
Abstract Number: 336 Working Group: Health Related Aerosols
Abstract Epidemiological studies identified increasing particulate matter (PM) concentrations as a reason for elevated mortality even at concentrations below regulatory thresholds. For 2017, exposure to ambient PM was among the 5 leading mortality risk factors causing up to 4.33 million deaths worldwide (Lelieveld et al., 2017; Cohen et al., 2017). Compounds present in PM such as trace metals and organic compounds can carry/produce reactive oxygen species (ROS) upon inhalation of PM and further oxidize target molecules in the body leading to oxidative stress. It is hypothesized that such oxidative stress is a key variable in explaining the observed adverse health effects. The ability of PM to induce such oxidative activity, termed oxidative potential (OP), has been put forward as a measure closely related to biological responses. It is expected that PM’s chemical composition is relevant in predicting its impact on human health.
In this study, we assess the spatial and temporal variability in the chemical composition of particulate matter < 10 µm (PM10) and study the association between OP and the different PM10 sources. We quantified the organic (OA) and inorganic (EC, NH4+, NO3-, SO42-, trace metals) constituents of PM10 as well as the OP (three complementary acellular assays: dithiothreitol (DTT), ascorbic acid (AA) and dichlorofluorescein (DCFH)) at various sites in central Europe (rural background, wood burning influenced, traffic influenced). We use an aerosol mass spectrometer in combination with positive matrix factorization to quantify the sources of organic aerosols collected on offline filter samples and analysed them at a molecular level with ultra-high resolution mass spectrometry (Orbitrap-MS). We demonstrate that the factors governing air quality are region-specific. Coarse vehicular wear, the dominant source of trace metals, is strongly enhanced in urban areas. The winter-time OA pollution in alpine valleys is driven by primary organic aerosol from wood burning emissions (BBOA) and at the other sites a largely non-fossil SOA factor correlating with anthropogenic secondary inorganic species is dominant. We observe the production of mainly non-fossil SOA in summer, following the increase in biogenic emissions with temperature. The predominance of highly oxygenated compounds with monoterpene related carbon backbone (carbon number 8-10, H:C ratio ~1.5) observed with Orbitrap-MS for summer samples suggest that OA during this period is dominated by biogenic SOA. We determined the contribution of the aerosol sources/components to the OP. Aerosol’s OP activity per mass quantified in this study provides reliable information for predicting ROS exposure levels for populations. We will present this thorough assessment of local and regional sources affecting air quality and human health.
Lelieved, J.: Clean air in the Anthropocene, Faraday Discuss., 200, 693-703, 2017.
Cohen, A. J., et al.: Estimates and 25-year trends of the global burden of disease attributable to ambient air pollution: an analysis of data from the global burden of diseases study 2015, Lancet, 389, 1907-1918, 2017.