Secondary organic aerosol

[1] In contrast to primary organic aerosols, which are emitted directly from the biosphere, SOAs are either formed via homogeneous nucleation through the successive oxidation of gas-phase organic compounds, or through condensation on pre-existing particles.

Upon oxidation, the increased polarity, and thus reduced volatility, of the molecules results in a reduction of vapor pressure.

[1] Biogenic volatile organic compounds (BVOCs) emitted by plants serve as a significant SOA precursor.

Anthropogenically emitted volatile organic compounds (VOCs), such as aromatics from fossil fuel combustion, can also be oxidized by such regimes.

[2] Dimethylsulfide (DMS) emitted by marine phytoplankton represent another significant SOA source.