Identifying high-risk workplaces for radon: The role of buildings' foundations and underground water sources

Radon, a naturally occurring lung carcinogen, can seep into buildings and expose occupants, including workers. Our aim is to describe radon exposure in various workplaces, identify factors associated with exposure, and highlight levers for preventive action.

Workplaces with an underground or slab-on-grade work area were recruited in four regions of Québec (Central Canada) with high and low potential for radon emissions. Long-term radon samples were taken during the cold season with Alpha Track AT-100 passive dosimeters, deployed by the research team in accordance with Health Canada's Guide for radon measurements in public buildings.

There were 354 radon measurements in 57 buildings constructed between 1877 and 2021 (54 workplaces), with on average six measurements (1-28) per workplace during a median of 109 days. Ten buildings had all measurements below the detection limit (15 Bq/m³), and six had at least one measurement above 100 Bq/m³. The highest values recorded were in a fish hatchery (>1500 Bq/m³). Generalized estimating equations revealed that a lowest floor made of materials other than poured concrete, the presence of naturally occurring radioactive material (underground water), and a small building footprint were the most predictive factors of higher concentrations, regardless of the regional radon emission potential.

In this convenience sample, most workplaces presented radon concentrations well below guidelines. However, the surprise expressed by workplace managers and public health officials regarding high concentrations associated with NORM is evidence of a lack of awareness of the dangers of radon in these environments.