Disclosed herein is a photocatalytic air purifier. The purifier (1 ) comprises an air passage (10), a plurality of catalyst screens (11) arranged oblique to the right angle of the axis of air flow through the air passage (10), a drive means (30) to force air through the air passage (10), a plurality of electromagnetic radio wave sources (13) to activate the catalyst screens (11) and the air within the air passage (10). The plurality of electromagnetic radio wave sources (13) are disposed within the air passage between adjacent screens (11).
