Oxidant and precursor trends in the metropolitan Los Angeles region

This paper describes recent htstorical trends in oxidant and precursors in the Los Angeles region. Control strategies and basin-wide emission trends for nitrogen oxides and reactive hydrocarbons are documented year by year from 1965 to 1974. Trends in the geographic distribution of emissions are illustrated by computing net percentage emission changes over the decade for individual counties. The changes in emissions are compared to changes in ambient precursor concentrations and oxidant concentrations. It is found that many of the changes in monitored air quality can be explained by trends in total emissions and in the spatial distribution of emissions.