Formaldehyde in your home
Formaldehyde is a volatile organic compound (VOC) that is commonly found in the indoor air of homes. Learn about sources of formaldehyde, its health effects and how to lower exposure to formaldehyde in your home.
On this page
- Sources of formaldehyde in indoor air
- Health effects of formaldehyde
- Recommended exposure limits in indoor air
- Levels of formaldehyde found in Canadian homes
- How to lower exposure to formaldehyde in your home
- Testing your home for formaldehyde
Sources of formaldehyde in indoor air
Formaldehyde can enter indoor air in two ways:
- combustion (burning materials)
Off-gassing is when construction or renovation materials, furniture, cabinets and household products release formaldehyde. Products that release formaldehyde include:
- chemical products such as:
- floor finishes
- household products such as:
- paper products
- permanent press fabrics like drapery
- composite wood products that use glues containing formaldehyde:
- medium-density fibreboard
- hardwood plywood paneling
Sources of formaldehyde from combustion (burning materials) include:
- tobacco smoke
- improperly vented gas or oil burning appliances
- smoke from fireplaces and wood-burning stoves
- vehicle exhaust from outdoors, or attached garages
In general, off-gassing sources release less and less formaldehyde over time. However, it can take weeks, and sometimes even months or years, to disappear completely. Levels may be generally higher in newly built or newly renovated homes. More formaldehyde is also released on hot and humid days, so levels are often higher in the summer and in warmer climates.
Health effects of formaldehyde
Formaldehyde is an irritant. Exposure to high concentrations can cause burning sensations in the eyes, nose and throat.
Long-term exposure to moderate concentrations (at levels lower than those causing irritation) may worsen asthma symptoms. This is particularly true in children and infants. It may also be linked to other respiratory symptoms and allergic sensitivity.
Formaldehyde is classified as "carcinogenic to humans" by the International Agency for Research on Cancer (IARC). It is linked to a rare type of cancer of the nasal cavity in industrial workers who are regularly exposed to very high concentrations over several years. These levels are much higher than those you would typically encounter in your homes. The risk of developing cancer from exposure to formaldehyde at concentrations found in most Canadian homes is very low.
Health effects at different levels of formaldehyde
At low levels of formaldehyde (below 50 μg/m3 or 40 ppb):
- no adverse effects are expected
At moderate levels of formaldehyde (above 50 μg/m3 or 40 ppb):
- long-term exposure may result in respiratory and asthma symptoms, especially in children. Symptoms include:
- allergic sensitivity
At high levels of formaldehyde (above 123 μg/m3 or 100 ppb):
- the risk of irritation or burning sensation in eye, nose and throat from short-term exposure increases with concentration
- the chances of respiratory symptoms are higher from long-term exposure
Recommended exposure limits in indoor air
We recommend maximum exposure limits for 2 types of exposure:
- short-term exposure: 123 µg/m³ or 100 ppb based on a 1-hour average to protect against irritation of the eyes, nose or throat.
- long-term exposure: 50 µg/m³ or 40 ppb based on a minimum 8-hour average, to protect against respiratory symptoms in children with asthma.
The short-term exposure limit protects against health problems that may arise from exposure to high levels over a short time period (for example, 1 hour). This type of exposure could occur, for example, when working with paint or varnish containing formaldehyde. Our recommended short-term exposure limit is set at 10 times less than the lowest level at which symptoms have been observed, to help protect the most sensitive individuals.
The long-term exposure limit protects against health problems that repeated exposure to lower levels of formaldehyde may cause over a long period. We consider a long period to be several months or years. Formaldehyde levels can change over time. The best way to measure long-term exposure levels is by sampling indoor air over a longer period (8 hours or more). Long-term exposure to formaldehyde at levels higher than the recommended exposure limit in indoor air has been associated with:
- airway inflammation
- increased allergic sensitivity
- physician-diagnosed asthma
Our recommended long-term exposure limit aims to protect children with asthma, who may be more sensitive to the effects of formaldehyde.
Our recommended exposure limits also protect you against the potential cancer risk.
Levels of formaldehyde found in Canadian homes
Health Canada has measured formaldehyde in a large number of homes in cities across Canada. On average, the levels measured over a day in Canadian homes were below the recommended long-term exposure limit (that is, approximately 10 to 40 μg/m3 or 8 to 32 ppb).
Formaldehyde levels in indoor air in homes depend on a number of factors including:
- the number and types of sources in the home
- the amount of ventilation: fresh air brought inside will lower indoor levels
- temperature and humidity: higher temperature and humidity will increase levels through off-gassing from some products
How to lower exposure to formaldehyde in your home
The best way to control formaldehyde in indoor air is to:
- ensure proper ventilation in your home
- decrease, eliminate or prevent the use of as many sources as possible
To lower formaldehyde levels in your home:
- increase your home's ventilation by bringing in dry, fresh air. Formaldehyde levels are higher indoors than they are outdoors.
To prevent levels of formaldehyde levels in your home from increasing:
- don't allow anyone to smoke inside
- choose low-emission household products when possible
- keep your fireplace, chimney and woodstove clean and clear of blockages
- don't leave cars or other gas powered equipment running in attached garages or near doors or windows
- keep the humidity at around 50% in the summer and 30% in the winter. Use a dehumidifier or humidifier, if necessary.
To prevent formaldehyde levels in your home from increasing when you are renovating:
- choose low-emission products when possible
- make sure to open your windows and increase ventilation, especially when:
- installing carpets using glues
- choose composite wood furniture or cabinet items with a plastic laminate or coating on all sides, or seal them yourself at home
Testing your home for formaldehyde
Testing your home for formaldehyde is generally not necessary. If you are concerned that levels may be high, the best option is to remove sources and increase ventilation. If you or your family members have symptoms related to formaldehyde or poor indoor air quality, talk to your health care provider.
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