Workers Health & Safety Centre

Testing and tackling radon exposures in Ontario workplaces

New research on radon in Ontario workplaces is calling for more testing to identify those most at risk of exposure to the known carcinogen.

Radon is a colourless, odourless gas and a well-documented carcinogen but you must test to detect its presence. Radon gas naturally occurs with the breakdown of uranium in soil and rock and can build up in the lower levels of buildings. Exposure to radon in our homes is a real concern, but researchers are now studying the potential for low level exposures in workplaces too.

A new study helps fill this knowledge gap. Its findings can educate workplaces on the hazards of radon and support calls for expanded radon testing, more workplace remediation, and safer, legally binding exposure limits.


Measuring workplace exposures

In Ontario, radon is responsible for 13 per cent of lung cancer deaths, second only to smoking. CAREX Canada estimates 34,000 Ontario workers are exposed to radon though their work. Studies on lung cancer among uranium miners exposed to radon still inform research efforts today, but researchers now believe many more workers might be exposed to low levels of radon in indoor workplaces when it seeps in through cracked building foundations, unfinished floors, or sump pumps.
For this study, funded by the Ministry of Labour, Immigration, Training and Skills Development (MLITSD), researchers from the Occupational Cancer Research Centre (OCRC), the Radiation Safety institute of Canada (RSIC) and Simon Fraser University set out to measure these types of workplace exposures.
Researchers measured radon levels in a variety of workplaces: small-medium sized, some in public buildings and others which operated in basements. In total, 453 workplaces and 435 employers from 10 Ontario cities participated: Elliot Lake, Sudbury, Ottawa, Kingston, Toronto, Guelph, Brantford, Woodstock, Chatham-Kent, and Windsor. Cities included those with known high and low background levels of radon.
Radon monitors tested workplaces over a three-month period during winter months to avoid the impact of open windows and doors. Data was collected and analyzed from 687 radon monitors. Participating workplaces completed surveys to provide additional information on business and building characteristics.  

Workplaces with elevated exposures

Key findings of the study were presented at a recent seminar. Researchers reported:
  • Most workplaces had low radon levels, but some were above guidelines used by Health Canada (200 Bq/m3 or Becquerels/cubic metre) and the World Health Organization (WHO) (100 Bq/m3)
  • Workplaces in areas with high background radon tested higher than those with lower background levels with levels being higher for workplaces in basements
  • Smaller workplaces (by sq ft) had higher levels than the largest workplaces
  • Chatham workplaces had the highest radon readings and Toronto the lowest.

Participating workplaces received their radon testing results with additional resources, guidance and contacts provided to those with levels above the WHO guideline.

The City of Greater Sudbury was one participant with elevated radon levels, including at a community centre which exceeded Health Canada guidelines and five other areas that tested above WHO guidelines. An FAQ on their web site notes, “In an abundance of caution, the City is undertaking remedial measures immediately,” which included closing some work areas and improving ventilation. The City also worked closely with their joint health and safety committees, held information sessions with workplace representatives and impacted workers, released a public service announcement, and assisted workers with exposure reporting to the Workplace Safety and Insurance Board.

A precautionary approach needed

The Canadian Guidelines for Management of Naturally Occurring Radioactive Materials (NORM) recommends 200 Bq/m3 as the workplace action level, with the goal to reach levels as low as reasonably achievable. Health Canada recommends the same action level for homes. The World Health Organization however recommends reducing radon levels to less than 100 Bq/m3 based on evidence of increased risk of lung cancer at very low levels of exposure.

Under Ontario’s Occupational Health & Safety Act (OHSA) employers must take every reasonable precaution to protect workers from hazards, including exposure to radon. Requirements to monitor and measure radon in underground mines exist in Regulation 854 (Mines and Mining Plants) under the OHSA, but for all other workplaces, MLITSD considers the NORM guidelines during enforcement.

The study authors encourage more testing of workplaces with high background radon, those which employ workers in basements or below ground level, and small workplaces. Adopting a precautionary approach, workplaces can reduce radon exposures by:
  • monitoring levels as part of a surveillance program
  • installing radon gas mitigation systems
  • ensuring ventilation systems are adequate
  • choosing low radon-containing materials
  • developing an exposure reduction program.

Longer term prevention goals include development of a radon-specific regulation under the OHSA and setting a 100 Bq/m3 radon action limit for all workplaces.

WHSC training for recognition and prevention

Workers Health & Safety Centre (WHSC) assists workplaces too through training and resources to raise awareness of hazardous exposures, including radon and others which can contribute to the burden of cancer, and the need for targeted prevention action in workplaces and communities.
WHSC is an approved provider of mandatory Certification Training for joint health and safety committee members who have the legal power to identify hazards and help resolve health and safety issues. Similar training is available for worker health and safety representatives in smaller workplaces who have similar rights aimed at creating safer, healthier work. WHSC Supervisor Training helps employers and supervisors meet and exceed awareness and competency requirements critical to their significant obligation to protect workers. 

Register for our $20 ergonomics courses, regularly priced at $75 to $120,  scheduled in support of RSI Awareness Day and its objectives.

In recognition of Day of Mourning for the first time ever, WHSC is offering a special 20 per cent discount for most scheduled training during the month of April.

Register today!
WHSC-related articles:
Low-level, prolonged exposure to radon leading cause of lung cancer
Radon exposure in Canadian schools focus of new research

Related Resources:
Seminar: Radon Survey of Workplaces in Ontario (review and download seminar presentations)
OCRC Radon Survey of Workplaces in Ontario (includes infographics, facts sheets and other resources)
City of Greater Sudbury: Radon Testing: Elevated Levels at Some City Facilities
CAREX Canada Radon Exposure Profile
Canadian Guidelines for the Management of Naturally Occurring Radioactive Materials (NORM)
Government of Ontario: Radon in the Workplace
Take Action on Radon

Need more information?
Contact a WHSC training services representative in your area
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