Using a catalytic chemical reaction from titanium dioxide and UVC light exposure, oxidation of organic matter converts pathogens, pollens, and mold spores into harmless inert byproducts. The cleansing mechanism of UV is a photochemical process. Contaminants in the indoor environment are almost entirely organic carbon-based compounds, which down when exposed to high-intensity UV at 240 to 280 nm. Short-wave ultraviolet light can destroy DNA in living microorganisms.^{citation needed} UVC’s effectiveness is directly related to intensity and exposure time.

UV light has also been shown to reduce gaseous contaminants such as carbon monoxide and VOCs.^[51][52][53] UV lamps radiating at 184 and 254 nm can remove low concentrations of hydrocarbons and carbon monoxide,if the air is recycled between the room and the lamp chamber. This arrangement prevents the introduction of ozone into the treated air. Likewise, air may be treated by passing by a single UV source operating at 184 nm and passed over iron pentaoxide to remove the ozone produced by the UV lamp.