Kinetics of submicron oleic acid aerosols with ozone

Heterogeneous reactions involving particles and gas-phase species can alter important chemical and microphysical properties of aerosols, complicating modeling efforts to assess their effects on climate and human health. Organic aerosols are usually the most abundant component of fine aerosols (< 2 µm) after sulfates, and it is in this size range that one finds those aerosols responsible for the majority of environmental effects 1. Precursors to organic aerosols include vegetation, the ocean surface, and various combustion processes. Ozone is an important oxidant in the troposphere, often in concentrations sufficient to cause adverse effects on human health and vegetation 2. Oleic acid is one of a group of organic species proposed as an important tracer species for use in source characterization of ambient aerosols 3. However, the relative fraction of these species may change as the particle ages, and new product species are likely to be introduced. Very little is known about the kinetics of organic species in atmospheric aerosols. Such knowledge is necessary for quantitative assessment of field studies as well as for use in climate and air quality models often relied upon for regulatory policy decisions intended to safeguard human health. The relatively recent field of aerosols kinetics has grown out of more general efforts to study gas-liquid interactions. The experimental exploration of such interactions includes approaches involving aerosol levitation devices, Knudsen cells, smog chambers,