An experimental study of the oxidation of hydrogen sulfide and formaldehyde impurities in humid air by ultraviolet radiation at wavelengths of 184.95 and 253.65 nm has been carried out at a pressure of 1 atm, an initial temperature of 20 °C, a relative humidity of 90%, and a flow rate of the gas mixture of 4920 m3/h. The initial concentrations of hydrogen sulfide and formaldehyde in air ranged from 8 to 20 and from 2.9 to 7.2 mg/m3, respectively. The photochemical kinetic mechanism was proposed for a numerical simulation of the low-temperature photooxidation of hydrogen sulfide and formaldehyde pollutants as well as the formation of ozone in humid air. The mechanism consists of 7 and 4 photochemical reactions initiated by UV radiation at wavelengths of 184.95 and 253.65 nm, respectively, and 62 reversible individual chemical reactions involving 32 chemical species (radicals, atoms, and molecules). The obtained results of numerical simulation are in good agreement with experimental data.