Some causes for indoor air pollution are

1) Formaldehyde is used in plywood, particle board and glues; it's found in most cabinets, carpets and walls, leads to some kind of indoor air pollution.

2) Benzene is a petrochemical; it's used in detergents, latex paints, oils, foams, dyes and rubber. It's common in building materials, exhaust fumes, and especially in cigarette smoke. Benzene is even found in some pharmaceuticals and it's known to induce leukemia.

3) Trichloroethylene is found in paints, lacquers, carpet shampoos, spot removers and adhesives. It's also used in dry cleaning, although this is becoming less so. Since trichloroethylene has contaminated some of the water supply, it can also enter the air of your home from shower vapors. Trichloroethylene is a central nervous system depressant.

4) Carbon monoxide is found in homes with gas stoves, and it's regularly found in high concentrations with worn or poorly maintained furnaces. Carbon monoxide also enters homes with attached garages from car exhaust. In high levels, carbon monoxide can cause sudden death.