Understanding the sources, formation processes and composition of atmospheric organic aerosols

Organic aerosols (OAs) are a major component of ambient particulate matter (PM) and play a vital role in regional air quality, human health and climate change. A significant fraction of OAs are of secondary origin as they are formed via complex atmospheric oxidation processes with volatile and semi-volatile organic compounds (VOCs). A better understanding of secondary organic aerosols (SOAs) is necessary for the implementation of effective air quality policies that mitigate adverse health, visibility and climate effects. Poor characterization of SOAs has led to widespread negative bias in model predictions of OAs. However, studies based on using molecular markers in the source apportionment approaches have shown remarkable improvement on the identification of secondary sources. Initially, approaches that use filter-based markers are not able to provide any information on SOA formation processes due to a lack of sampling resolution. Further development by incorporating data from different instrumentation (e.g., aerosol mass spectrometry) in the source apportionment models have resulted in a much better understanding of OAs over the conventional approaches. Despite all efforts, it has not been possible to comprehensively understand SOAs due to the complexity and variability of sources and atmospheric processes involved in their formation and evolution within the atmosphere. There is a great need to understand SOAs formation mechanism through collaborative laboratory, field and modelling studies. Results from field studies performed in France and USA, and lab studies from the collaborative work between Birmingham and Beijing are presented