The reaction mechanisms of products, along with their rates of reaction with hydroxyl radicals and their rates of photolysis, have been used to obtain carbon monoxide, CO, yields from the products of the homogenous atmospheric photooxidation from emissions of hydrocarbons and other volatile organic compounds, VOCs. Seasonally averaged CO yields are estimated for a number of types of VOCs. The annual production of CO is estimated for the contiguous United States from combustion sources of CO and from the atmospheric photooxidation of anthropogenic and biogenic emissions of volatile organic compounds. Limitations on estimates of CO yields and of CO production from various heterogeneous processes are discussed. (Copyright (c) 1991 Kluwer Academic Publishers.)