Quantifying the contribution o...

Quantifying the contribution of emissions from combustion systems to ambient organic aerosols

Motor vehicles, wood stoves, and other combustion systems are major sources of organic aerosols. This talk synthesizes results from recent smog chamber studies of motor vehicle emissions, open biomass burning emissions, and aircraft exhaust that highlight the chemistry and physics that control the contribution of these sources to atmospheric aerosol levels. The results reveal a picture of dynamic partitioning and dramatic changes with oxidation. This new picture alters our understanding of the contribution of combustion sources to urban and regional pollution and brings chemical transport model predictions into better agreement with field observations. An important finding is that secondary organic aerosol production often greatly exceeds the direct or primary emissions from most combustion systems; therefore, it must be included in any assessment of the contribution of combustion systems to ambient organic aerosol concentrations. However, existing atmospheric chemistry models cannot predict the observed secondary organic aerosol production. Low-volatility organic vapors emitted by combustion systems appear to be very important secondary organic aerosol precursors that are poorly accounted for in inventories and models. Therefore, new approaches will likely be required to include these vapors in models. The talk concludes by discussing the implications that the dynamic nature of these organic aerosol emissions has on source testing for both emission inventory development and regulatory purposes.

Presentation Type: 
Invited Presentation
Author 1: 
Allen L. Robinson
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Corresponding Author: 
Allen L. Robinson
Presenting Author: 
Allen L. Robinson