Abstract
A recent laboratory measurement of the ratio of the rate constant for the reaction CO + HO 2 → C02 + OH relative to that for H + HO2 → 2OH indicates that the former reaction is probably faster than CO + OH → CO2 + H. On this basis a simple analysis is given showing that the calculated lifetime of nitric oxide in polluted atmospheres would be appreciably longer than that estimated on the assumption that the carbon monoxide-hydroperoxyl reaction may be neglected. A fast carbon monoxide-hydroperoxyl reaction implies that the cyclic consumption of carbon monoxide (an atmospheric sink) could occur even with no nitric oxide present.