Titanium dioxide is the most important white pigment used in the polymer industry. It is widely used, because it efficiently scatters visible light, thereby imparting whiteness, brightness, and opacity when incorporated into a plastic product.
Titanium Dioxide is also used in modern purification techniques employing semiconductor mediated photo-oxidation of toxic substances, where it breaks down harmful volatile organic chemicals (VOCs), polyaromatic hydrocarbons and nitrogen oxides.
A new development among paint, pigment, and cement manufacturers is combining these two uses of TiO2 and make paint and concrete surfaces that clean themselves with photochemical reactions. Adding activated TiO2 pigment into a paint mix helps to reduce VOC emissions from the painted surface. Concrete surfaces with activated TiO2 have been used to reduce traffic-related NOx levels in tunnels for instance.