New research from the University of Liverpool shows that formaldehyde airborne concentrations in most NHS cell pathology departments are monitored infrequently and regularly exceed EU work exposure limits (WELs).
The study, published in the BMJ’s Occupational and Environmental Medicine, underscores the importance of aligning UK standards with the EU and implementing stricter occupational health measures.
A substantial body of occupational exposure data shows that formaldehyde inhalation is associated with myriad short- and long-term harmful health effects on the respiratory, female reproductive and nervous systems. It is also a human carcinogen.
Cell pathology departments are among the riskiest occupational environments for formaldehyde inhalation exposure and therefore require a high standard of governance and infrastructure to adequately protect staff.
The researchers requested 12 months of formaldehyde monitoring data from 122 NHS Trusts across the UK. Data included frequency, number of measurements, and airborne concentration ranges.
The study assessed whether monitoring frequency and concentrations met safety standards, applying EN 689:2018 standards for statistical evaluation.
A total of 1,715,516 formaldehyde airborne monitoring results were disclosed by 117 NHS cell pathology departments. Monitoring was infrequent, with 73% of sites measuring formaldehyde airborne concentrations once weekly or less, using portable spectrophotometric or electrochemical sensors.
The EU long-term WEL was exceeded regularly at 70% of sites (95th percentile >0.3 ppm), and the EU short-term WEL was exceeded regularly at 43% of sites (95th percentile >0.6 ppm). The 95th percentile upper tolerance limit (UTL95,70) exceeded the EU short-term WEL at 68% of sites.
Only 11% and 17% of departments demonstrated frequent (once daily or more) formaldehyde airborne monitoring with 95th percentiles below the EU long- and short-term WELs, respectively.
Due to increasing concern over formaldehyde’s toxicity, the EU introduced new binding formaldehyde workplace exposure limits in 2021 of 0.3 parts per million (ppm) (long term 8-hour time-weighted average) and 0.6 ppm (15-minute short-term exposure limit).
But the UK left the EU in 2020, so didn’t have to adopt them, instead maintaining the world’s highest formaldehyde workplace exposure limit of 2ppm for both long- and short-term exposures. While none of the sites exceeded the UK short and long term workplace exposure levels, nearly a third (30%; 35) had recorded an airborne formaldehyde level above 2 ppm at least once in the preceding 12 months.
Corresponding author Dr Magdalena Plesa from the University of Liverpool Management School said: “Our data raise concern for the health of thousands of NHS employees working in these environments. Urgent national regulatory intervention is now warranted to improve the occupational hygiene of NHS cell pathology departments.”
The study was conducted by Dr Plesa in collaboration with Dr Richard Yates, Royal Free London NHS Foundation Trust.
The researchers are now calling for national regulatory intervention, which they say would require a combination of upgraded infrastructure, more regular personal exposure monitoring, better employee education on basic laboratory practice and occupational health risks, improved access to appropriate personal protective equipment, management accountability for occupational health, and external oversight by the Health and Safety Executive.
- Plesa M, Yates RL. Under the microscope: formaldehyde exposure in National Health Service pathology departments in the United Kingdom. Occup Environ Med. 2026;0:1–7. Epub ahead of print: doi:10.1136/oemed-2025-110545