This embalming fluid is almost inescapable in modern indoor environments, released into the air from the glue which holds together particleboard and plywood. High humidity or moisture disintegrates the glue and increases formaldehyde release. Formaldehyde is used to stiffen fabrics of all types, so that new clothing, carpeting and upholstered furniture may off-gas considerable formaldehyde for days or weeks. Wrinkle-proof clothing has been treated with a formaldehyde resin and will give off formaldehyde forever. Particle board construction materials and furniture can be treated with a lacquer that seals formaldehyde in and keeps moisture out.
Tobacco smoke releases benzene into the air.
Benzene exposure in humans is a cause of leukemia, the leading form of childhood cancer in the United States. A radioactive gas which enters your house from the soil. Scientists estimate that seventeen million homes in the U.S. may still contain unacceptable radon levels.