An exposure apparatus includes a radiation system configured to supply a projection beam of radiation, and a patterning device configured to pattern the projection beam according to a desired pattern. The apparatus includes a substrate table having an area configured to support a substrate, and a projection system configured to project the patterned beam onto a target portion of the substrate. At least a part of the apparatus that during use of the apparatus is exposed to radiation is coated with a coating. The coating includes a metal oxide, or a photocatalyst, or a semiconductor, or any combination thereof.