Hydrocarbons and Carbonyls in Los Angeles Air

Simultaneous measurements of individual hydrocarbons and individual carbonyls were carried out at a downtown Los Angeles location. Concentrations are presented for 50 compounds in morning air samples. While paraffins (C ≥ 4) were a major hydrocarbon subclass on a ppmC basis, higher aromatics (C ≥ 8) were the major component when taking reactivity considerations into account. Comparison of the results with emission inventory data showed good agreement for many hydrocarbons and for paraffins as a subclass. Measured olefins and aromatics concentrations were substantially lower and higher, respectively, than those expected from inventory data.