Find out about formaldehyde, its sources and health risks. 

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About formaldehyde

Formaldehyde is a colourless gas commonly found in indoor air.

Low levels in indoor air are common. When present at high levels, it can be detected by a strong smell.

Indoor sources of formaldehyde

Formaldehyde can enter indoor air in two ways:

  1. activities involving burning, such as smoking cigarettes
  2. off-gassing (release of gases) from household products and building materials

Indoor sources of formaldehyde include:

  • adhesives
  • smoke from:
    • fireplaces
    • wood-burning stoves
  • tobacco smoke
  • finishes, such as:
    • paints
    • varnishes
    • floor finishes
  • vehicle exhaust from:
    • the outdoors
    • attached garages
  • household products, such as:
    • wallpaper
    • paper products
    • cardboard products
  • manufactured wood products (often used to make furniture, cabinets or building materials), such as:
    • particle board
    • medium-density fibreboard
    • hardwood laminate flooring
    • hardwood plywood paneling

The amount of formaldehyde released from off-gassing decreases over time. However, for it to disappear completely, it can take months to years.

Health effects of formaldehyde

Formaldehyde is an irritant. If you are exposed to high levels of the gas, it can cause burning sensations in your:

  • eyes
  • nose
  • throat

If you have asthma, you may be more sensitive to formaldehyde.

Long-term exposure to:

  • moderate levels (levels lower than those causing irritation), especially for children, may also be linked to:
  • breathing problems
  • increased allergic sensitivity
  • very high levels (levels higher than those found in Canadian homes) can cause cancer of the nasal cavity
    • this is a rare type of cancer
    • formaldehyde has been linked to this cancer in industrial workers regularly exposed to high levels of the gas

There is essentially no risk of developing cancer based on average levels of formaldehyde found in Canadian homes.

How to reduce exposure to formaldehyde in the home

The best way to control formaldehyde in the air is to:

  • prevent it from getting into the air in the first place
  • reduce or eliminate as many sources as possible

You can reduce formaldehyde levels in your home by:

  • avoiding smoking indoors
  • ensuring plenty of ventilation when you:
    • do major painting or varnishing projects
    • install wall-to-wall carpets using glues or adhesives
  • preventing smoke from getting into your home by:
    • keeping your chimney clean and unblocked
    • ensuring fireplaces and woodstoves are in good working condition
  • keeping emissions low from pressed wood furniture or cabinets by:
    • buying items that are low-emitting, or have a plastic laminate or coating on all sides
    • sealing these items yourself at home
  • airing out products that contain formaldehyde before bringing them indoors
  • using building and household products with no or low-formaldehyde options, if available
    • ask retailers or manufacturers for details

Engine exhaust also contains formaldehyde, along with other toxic chemicals. To prevent them from getting into your home, you should avoid leaving vehicles idling or operating any gas-powered equipment:

  • in attached garages
  • near doors or windows

Formaldehyde levels are typically higher indoors than outdoors. You can significantly decrease indoor levels by letting in fresh outdoor air.

Canada’s recommended exposure limit for formaldehyde

Canada has developed an indoor air quality guideline for formaldehyde in homes. The guideline sets recommended maximum formaldehyde levels to protect against health problems that may arise from short- and long-term exposure.

Short-term exposure refers to exposure to formaldehyde over a short time period, such as 1 hour.

Long-term exposure refers to repeated exposure to formaldehyde over a long period, from days to years.

About urea formaldehyde-based foam insulation (UFFI)

Urea formaldehyde-based thermal insulation (UFFI):

  • is a foam that was once used to insulate buildings
  • has been banned in Canada under the Hazardous Products Act since 1980

UFFI was banned due to the:

  • high levels of formaldehyde that were given off during installation
  • continued off-gassing of formaldehyde from poorly installed insulation

The amount of formaldehyde released by UFFI was highest when the insulation was first installed but decreased over time. As a result, UFFI installed before 1980 would have little effect on indoor formaldehyde levels today.

However, if UFFI gets wet, it could begin to break down and may release more formaldehyde into the air.

Where wet or deteriorating UFFI is present:

  • it should be removed by a specialist
  • the source of the moisture problem should be repaired

For more information

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