Titanium dioxide, or TiO2, sometimes referred to as E171, is an inorganic, solid substance used in a wide range of consumer goods including cosmetics, paint, plastic and food, according to the American Chemistry Council.

Below are selected applications of photocatalytic pollutant decomposition processes on titanium oxide:
1. Self-cleaning surfaces: for the production of glass for spotlights, traffic lights, car mirrors, window panes, for road paints, for covering sound-absorbing screens and tunnel walls.
2. Air cleaning and odor removal: filters that are used in enclosed spaces (e.g. public toilets) or filters for air-conditioning equipment.
3. Water treatment: groundwater treatment installations, water purification installations in the intakes of drinking water from rivers.
4. Self-disinfecting materials: towels, linings, clothing, equipment in hospitals, wall surfaces of operating rooms.
5. Removal of lesions: anti-cancer therapy.