Characterizing occupational radon exposure greater than 100 Bq/m3 in a highly exposed country

Abstract

Radon is an established lung carcinogen concentrating in indoor environments with importance for many workers worldwide. However, a systematic assessment of radon levels faced by all workers, not just those with direct uranium or radon exposure, has not previously been completed. The objective of this study was to estimate the prevalence of workers exposed to radon, and the level of exposure (> 100–200 Bq/m3, 200–400 Bq/m3, 400–800 Bq/m3, and > 800 Bq/m3) in a highly exposed country (Canada). Exposures among underground workers were assessed using the CAREX Canada approach. Radon concentrations in indoor workplaces, obtained from two Canadian surveys, were modelled using lognormal distributions. Distributions were then applied to the susceptible indoor worker population to yield the number of exposed workers, by occupation, industry, province, and sex. In total, an estimated 603,000 out of Canada’s 18,268,120 workers are exposed to radon in Canada. An estimated52% of exposed workers are women, even though they comprise only 48% of the labour force. The majority (68%) are exposed at a level of > 100–200 Bq/m3. Workers are primarily exposed in educational services, professional, scientific and technical services, and health care and social assistance, but workers in mining, quarrying, and oil and gas extraction have the largest number of exposed workers at high levels (> 800 Bq/m3). Overall, a significant number of workers are exposed to radon, many of whom are not adequately protected by existing guidelines. Radon surveys across multiple industries and occupations are needed to better characterize occupational exposure. These results can be used to identify exposed workers, and to support lung cancer prevention programs within these groups.

Consequences of changing Canadian activity patterns since the COVID-19 pandemic include increased residential radon gas exposure for younger people

“…The balance in time spent between residential and non-residential environments matters as many North American occupational environments carry lower radon exposure risks due to safety programs in operation for many years, some commencing as early as the 1970s in the mining sector 21,[39][40][41] . Such programs have successfully lowered radon levels within many public and private workplace building portfolios, with notable examples in Canada being all federal and many provincial and municipal government-operated facilities (e.g., administration, national parks, border control, military, national police, prisons, and education) [42][43][44][45] . Further to this, ventilation controls in buildings such as office towers, hospitals, retail malls, hotels, factories, etc.…”

“…Further to this, ventilation controls in buildings such as office towers, hospitals, retail malls, hotels, factories, etc. typically operate with greater air exchanges and/or positive pressure versus a typical residential property, and so are more likely to produce indoor air with lower overall radon risk 42,46 . Measuring shifts in the relative amount of time per year between environments with differing environmental carcinogen risks is critical to understand future cancer burdens.…”