This project measured radon levels in a variety of Ontario workplaces, including public buildings and small to medium sized businesses. The main objective of this study was to collect data to assess where hazardous levels of radon are present in Ontario workplaces to target prevention efforts.
Radon is an invisible, naturally occurring radioactive gas formed by the breakdown of uranium in soil, rock and water. It can accumulate to high levels in enclosed spaces and can only be detected by radon measurement devices. Radon is responsible for approximately 14% of lung cancer deaths in Ontario and is the second leading cause of lung cancer after smoking [1]. The World Health Organization recommends that radon exposure remain below 100 Bq/m3, while the Health Canada Guideline is 200 Bq/m3 [2,3].
In Ontario, research on radon exposure in workplaces has been very limited, other than in uranium mines. While radon testing was completed in the late 1990s in Ontario fish hatcheries, these results are now outdated and no other large-scale study of radon in workplaces in the province has been undertaken.
Regions of Ontario with low and high background radon levels were identified using results from the residential Cross-Canada Survey of Radon [4]. Six cities in high background areas (Brantford, Chatham-Kent, Guelph, Kingston, Windsor, and Woodstock) and four cities in low background areas (Elliot Lake, Ottawa, Sudbury, Toronto) were chosen for sampling. Small or medium sized businesses and workplaces in public buildings were eligible for recruitment, and these sites were recruited via phone, email, and in-person recruitment. Radon monitoring kits were deployed in participating workplaces for 3 months over the winter season, as radon levels are expected to be at their peak during colder months of the year. Questionnaires were administered to collect information about workplace and building characteristics.
A total of 453 workplaces participated in this study, and 687 radon measurements were collected. Out of all workplaces, 2.6% tested above the Health Canada guidelines. These workplaces were provided with free educational materials and connected with remediation and mitigation informational resources.
The data were analyzed to identify potentially high background risk zones and other building characteristics associated with high radon levels.
Thank you to all who participated! For participating workplaces, please reach out to Lily Yang (lily.yang@ontariohealth.ca) if you have any questions.
Final analyses of workplace questionnaire responses from the Radon in Ontario Workplaces study are complete, with a manuscript submitted in fall 2024.
This research will help fill crucial gaps in knowledge by generating new data on radon exposures and identifying regions in Ontario where levels of radon are elevated in the workplace. The results from the study can be used target prevention efforts in regions with the greatest potential for improvements. The research project also aims to increase radon awareness and health and safety knowledge among workers. The study’s findings may be further used by governments and health professionals to help prioritize radon outreach and education efforts, and to encourage workplace testing and remediation where necessary.
This study is funded by a grant from the Ontario Ministry of Labour, Training and Skills Development’s Research Opportunities Program:
Demers PA, Boksman L, McIntosh T, Nicol AM. Radon Survey of Workplaces in Ontario. 2017-2019.
