ESTIMATE OF THE NOX REMOVAL RATE IN AN URBAN ATMOSPHERE

A formulation for estimating the NOx removal rate by chemical reaction in an urban area is presented. Using the (NOx)/(CO) ratio from data obtained in the Los Angeles (LA) Basin, a lower bound for the yearly average removal rate of NOxduring daylight hours is found to be 4% h-1. Using the (PAN + HNO3)/(NO + NO2 + PAN + HNO3) ratio from data obtained during the summer months at West Covina (LA Basin) and St. Louis by Spicer et al., the average NOx removal rate during the daytime is also found to be 4% h-1. From this analysis, the average residence time for NOx in the LA Basin (all year) and St. Louis (summer) is estimated to be less than 2 days. © 1979, American Chemical Society. All rights reserved.