Possible mutagenic properties and carcinogenic action of the irritant gaseous pollutants NO2, O3, and SO2.

Carcinogenic or cocarcinogenic effects of NO2, O3, and SO2 have not been proven to date with sufficient reliability. However, nitrosamine formation after exposure to NO2- or O3-induced decrease in benzpyrene hydroxylase are potential hazards. A final revaluation of a possible cocarcinogenic action of SO2 requires further experimental studies.