The chemistry of oh and ho2 radicals in the earth's atmosphere

In the present review the main photochemical mechanisms for reaction of OH and HO2 with atmospheric components are examined and possible alternative methods of studying them are analysed. The mechanisms governing the change in concentrations of OH and HO2 radicals cannot be represented without a consideration of other stable and labile minor gas components in the atmosphere. Amongst the latter the most important are ozone, ozone-active radicals and their precursors, stable molecules. In addition to OH and HO2, NO, NO2, as well as Cl and CIO are also reactive towards ozone. The destruction cycles for ozone involving these radicals and reactions related to them are also briefly examined in this review together with the heterogeneous processes involving OH and HO2 that can also substantially affect the gaseous composition of the atmosphere.