The International Agency for Research on Cancer (IARC) at World Health Organization (WHO) classifies formaldehyde as a known human carcinogen associated with nasal sinus cancer and nasopharyngeal cancer. Recent studies have also shown a positive correlation between exposure to formaldehyde and the development of leukemia.
Professionals exposed to formaldehyde in their occupation, such as funeral industry workers, embalmers and home renovators showed an increased risk of leukemia and brain cancer compared with the general population.
Although workplace exposure to inhaled chemicals is among the most important risk factors, we are exposed to this carcinogen at our own home: formaldehyde can off-gas from wood products, such as plywood or particle board, produced by paints, varnishes, floor finishes, and cigarette smoking as well.
Formaldehyde can be found at low levels in all Canadian homes and buildings. Sources of formaldehyde in indoor air include:
- car exhaust from attached garages
- latex paints, glues, adhesives, varnishes and lacquers
- dishwashing liquids, fabric softeners, shoe polishes and carpet cleaners
- some cosmetics (like nail polish and nail hardener)
- wallpapers, cardboard and paper products
- some permanent press fabrics (like some curtains, sheets and clothing)
- furniture, cabinets and building materials (made from particleboard, medium density fibreboard, hardwood, plywood paneling, and certain moulded plastics)
- cigarette smoke
- smoke from wood stoves and fireplaces
Formaldehyde emits from a variety of construction materials, furnishings, and consumer products. The three products that emit the highest concentrations are:
- medium density fiberboard
- hardwood plywood
- particle board
Environmental factors such as temperature and relative humidity can elevate levels because formaldehyde has a high vapor pressure. Formaldehyde levels from building materials are the highest when a building first opens because materials would have less time to off-gas. Formaldehyde levels decrease over time as the sources suppress.
What is formaldehyde?
Formaldehyde is a colourless gas that is widely used around the world as a disinfectant and preservative. It is also used in many household products and building materials. When found at higher levels in the air, it has a sharp smell.
Formaldehyde levels in air are usually measured in micrograms (μg) of formaldehyde per metre cubed (m3) of air. A microgram is a very small amount equal to 1 millionth of a gram. Formaldehyde levels are also sometimes expressed as parts per billion (ppb). For example, a level of 1 ppb of formaldehyde means there is 1 part of formaldehyde in a billion parts of air.
Formaldehyde short-term exposure: To avoid possible eye, nose and throat irritation from short-term exposure, indoor air levels of formaldehyde should be below 123 μg/m3 (100 ppb). This is actually lower than the formaldehyde level that has been shown to cause irritation in scientific studies. The lower value was chosen to be more protective of health, as people may differ in their sensitivity to formaldehyde.
Formaldehyde long-term exposure: To prevent respiratory problems from long-term exposure, i.e. over days, months or years, indoor air levels should be kept below 50 μg/m3 (or 40 ppb). As formaldehyde levels increase above this level, the risk of having respiratory problems or allergic sensitivity also increases, especially for children.
Formaldehyde at home: Health Canada has measured formaldehyde in a large number of homes in different cities across Canada – Charlottetown, Ottawa, Quebec City, Regina – as part of an ongoing study on the quality of indoor air. All houses had at least some formaldehyde in indoor air. On average, formaldehyde levels measured over a day in Canadian homes were 20-40 μg/m3 (16-32.5 ppb). Daily levels as high as 95 μg/m3 (77 ppb), however, have been recorded. Formaldehyde levels indoors will depend on the number of formaldehyde sources in the home. Ventilation is also a factor, as fresh air brought in from outdoors will dilute and reduce indoor formaldehyde levels. Higher temperature and humidity will also increase the release of formaldehyde through off-gassing from some products.
Reduce the level of formaldehyde inside your home by following these tips:
- Make your home and car smoke-free. Don’t let anyone smoke inside.
- Keep fumes outside. Don’t run engines (like cars, lawnmowers or snow blowers) in attached garages or near doors or windows.
- Maintain wood stoves and furnaces.
- Look for products made with low or no formaldehyde. Ask before you buy.
- Wash permanent press clothing and sheets before you use them. Air out products like permanent press drapes before bringing them into your home.
- Seal pressed wood products. Buy pressed wood furniture or cabinets with a plastic laminate or coating on all sides. Or seal them yourself at home.
- Make sure there is plenty of ventilation during major painting or varnishing projects, or when installing wall-to-wall carpets using glues or adhesives.
- Control moisture levels inside your home. When humidity levels are high, products tend to release formaldehyde into the air at a faster rate.