Abstract: An air filter for attaching to a top and/or bottom surface of a fan blade. The air filter is constructed from an elongated strip of porous material capable of having air pass therethrough while trapping airborne particles borne by the air. Also, the elongated strip has opposed exposed surfaces and a peripheral edge extending therearound and preferably, an adhesive strip having opposite surfaces and an adhesive substance on each of the opposite surfaces is attached to one side edge of the elongated strip. The other opposed surface of the adhesive strip is preferably attached to a top and/or bottom surface of a fan blade. Thus, the filter strip sweeps and filters air moving across the one surface of the fan blade as the fan blade rotates.