What is it?
Formaldehyde is a colourless, pungent gas that occurs naturally in small amounts but is used industrially as a preservative, adhesive binder and disinfectant. It is released continuously from pressed wood products (MDF, plywood, chipboard), certain fabrics, paints, and personal care products containing formaldehyde-releasing preservatives. The WHO classified it as a Group 1 carcinogen in 2004. Indoor levels are consistently higher than outdoor levels, particularly in new builds and recently renovated homes.
What it does to your body
Respiratory irritation and asthma
Triggers airway inflammation even at low concentrations, worsening asthma and causing chronic respiratory irritation.
Cancer
Group 1 carcinogen: nasopharyngeal cancer and leukaemia confirmed in occupationally exposed workers; the WHO and IARC classification applies.
Skin sensitisation
Contact dermatitis from formaldehyde-releasing preservatives in cosmetics is a documented and common reaction.
Neurological effects
Headaches, brain fog and eye irritation occur at typical indoor exposure levels found in new-build homes.
Childhood development
Linked to increased asthma rates in children raised in homes with pressed wood furniture and high formaldehyde emissions.
How widespread is the problem?
The EPA estimates that indoor formaldehyde levels in new US homes average 0.076 ppm, above the WHO guideline of 0.05 ppm. An estimated 45 million American homes contain significant formaldehyde-emitting products. The problem is most acute in energy-efficient homes with reduced ventilation.
Where it hides in your home
Key research
IARC Group 1 Classification
International Agency for Research on Cancer classified formaldehyde as a confirmed human carcinogen, Group 1, based on nasopharyngeal cancer and leukaemia evidence.
EPA Formaldehyde Risk Assessment
EPA comprehensive risk assessment confirming carcinogenicity and setting reference concentrations for inhalation exposure.
WHO Indoor Air Quality Guidelines on Formaldehyde
WHO set a guideline value of 0.1 mg/m3 (0.08 ppm) for 30-minute exposure to protect against sensory irritation; 0.05 ppm recommended for chronic exposure.
Once you leave a formaldehyde-rich environment, blood levels fall within hours. However the source continues emitting. A new MDF furniture item can off-gas for 2 years. Removing or replacing the source, and ventilating aggressively, is the only effective strategy.