Both the formaldehyde and polychlorinated biphenyl (PCB) mentioned are found in common household products. PCB was banned from production in the U.S. in 1970 but persists in wire coatings, sealants, paints and wood floor finishes. Asbestos, another source of indoor air pollution that has been banned from widespread use, also still lingers in older homes, insulation materials, textured paints and floor tiles.