Formaldehyde Testing

It depends on the setting. For workers who handle formaldehyde, the workplace exposure limit (WEL) is 2 ppm (2.5 mg/m³) averaged over eight hours, with a short-term limit of 2 ppm over a 15-minute reference period. Both are listed in EH40/2005.

For general indoor air, the WHO guideline is 0.1 mg/m³ (100 µg/m³) averaged over 30 minutes, and certification schemes such as BREEAM and WELL set their own thresholds. HSE has noted that the formaldehyde WEL is under review, so check the current edition of EH40 for the latest figures.

We use area sampling in the room, personal sampling where staff wear a device through their shift, or both, depending on the question being asked. Results are compared with the limit or benchmark that applies, and we record how the room was used so that any high readings can be traced to a cause. 

Some can, with limits. Many portable air quality monitors include an electrochemical formaldehyde sensor, which is useful for screening and spotting peaks. These sensors have limited accuracy at low concentrations, can respond to other vapours such as alcohols and solvents, and drift over time, so they are not always accepted as evidence for compliance or certification.

A CO2 monitor tells you nothing about formaldehyde, and a TVOC reading cannot confirm it either way.

For results you can rely on, specific formaldehyde sampling is needed.

Anyone who handles formalin or works with formaldehyde-based materials, particularly in poorly ventilated rooms. That includes histology and pathology staff, mortuary and anatomy teaching staff, embalmers, and workers in wood panel, furniture and foundry processes. HSE highlights heated formaldehyde resins in foundries as a source.

HSE states that formaldehyde can irritate the eyes, skin and respiratory tract, and that prolonged exposure may cause skin sensitisation and allergic contact dermatitis. IARC classifies formaldehyde as carcinogenic to humans (Group 1), linked to cancers of the nose and throat and to leukaemia. Staff with health concerns should speak to their occupational health team or GP.

COSHH requires employers to assess and control exposure to hazardous substances, and formaldehyde has a WEL. Monitoring is required where it is needed to show that controls are working or to protect health, and the risk assessment decides that. Where staff handle formalin regularly, measured data is the strongest evidence that controls are effective.

Your risk assessment sets the frequency. Re-testing makes sense after changes to processes, ventilation, extraction, the volume of formalin used or fit-out materials, or when staff or occupants raise concerns. Because exposure varies with workload, a single test is a snapshot rather than a permanent answer.

The starting point is adequate ventilation, with extraction or LEV that captures vapour at the source, lidded containers, closed transfer of formalin and prompt spill clean-up. Substituting formalin where a suitable alternative exists removes the problem entirely. Testing shows which of these your room actually needs.

Yes. Composite wood, furniture, flooring and adhesives can release formaldehyde, most noticeably in new or newly refurbished spaces. Levels are normally far below the workplace limit, but they can still affect comfort. The WHO indoor air guideline is 0.1 mg/m³ over 30 minutes. Air quality monitoring can show how levels change over time.

Where the scheme includes post-completion indoor air quality testing, yes. BREEAM and WELL both set formaldehyde thresholds that measured results are compared against, and the criteria vary by scheme and version, so check the version your project is registered under.