Photocatalysts display strong oxidation and decomposition properties when exposed to sunlight or other ultraviolet light source and are used to eliminate volatile organic compounds and other toxic materials. Discovered in Japan in the 1970s, photocatalysts can remediate contaminants in a clean and environmentally friendly way. University of Tokyo scientists developed a titanium dioxide coating material around 1990 that destroys pollutants, fights bacteria, and acts as a deodorant under ultraviolet light. Such photocatalysts are now widely used to produce antibacterial tiles, tunnel light covers, and filters for air purifiers.