A contaminant reduction system comprises an assembly of appropriate size and shape for mounting within a sealed or semi-sealed hard disk drive (HDD). The system comprises a photocatalytic surface mounted in close proximity or in contact with a light source which may be utilized as a means for activation. The photocatalytic surface is preferably titanium dioxide (TiO.sub.2); it may be other metal oxide catalyss that can be photochemically activated such as zinc oxide (ZnO). The activation is achieved utilizing a lamp which illuminates the photocatalyst and has an output below 100 nm.