Smog Chemistry Points the Way to Rational Vehicle Emission Control

The results of studies of atmospheric chemistry of smog formation serve as guidelines for determining a rational basis for control of vehicle emissions. These guidelines indicate the desirability of reactive hydrocarbon reduction and the futility of nitric oxide reduction from vehicles.

A system of classifying hydrocarbons as to their reactivity in smog formation is presented. Its application, in combination with, gas chromatographic analyses, to both exhaust hydrocarbon and evaporative hydrocarbon vehicle emissions is illustrated. Utilization of this approach for determining the importance of exhaust versus evaporative hydrocarbon emissions, and for measuring efficacy of control by changes in both vehicles and fuel composition is recommended.