Atmospheric evolution and chemical aging of organic particulate matter

Organic particulate material has been traditional classified as either primary or secondary with the primary component being treated as non-volatile and inert. Laboratory and field studies during the last decade, demonstrate that primary combustion aerosol is highly dynamic, consisting of mostly semi-volatile material that moves between the gas and particulate phases in the atmosphere and at the same time is oxidized forming a variety of oxygenated products. This oxidation can lead to both lower volatility material through functionalization but also to smaller lower volatility molecules through fragmentation. A unifying framework for the description of all organic components based on their volatility distribution (the volatility basis set) can be used for the treatment of a wide range of processes affecting organic aerosol loadings and composition in the atmosphere. This modelling framework is combined with emission characterization studies, laboratory smog chamber studies, and field measurements to simulate the atmospheric evolution of these organic emissions.