Radon exposure is rising steadily within the modern North American residential environment, and is increasingly uniform across seasons

Fintan K T Stanley,Darren R Brenner,Weston R Jacques,Daniel G Innes,Aaron A Goodarzi,David Torr,Jesse L Irvine,Shilpa R Salgia,Brandy D Winquist

doi:10.1038/s41598-019-54891-8

Abstract

Human-made buildings can artificially concentrate radioactive radon gas of geologic origin, exposing occupants to harmful alpha particle radiation emissions that damage DNA and increase lung cancer risk. We examined how North American residential radon exposure varies by modern environmental design, occupant behaviour and season. 11,727 residential buildings were radon-tested using multiple approaches coupled to geologic, geographic, architectural, seasonal and behavioural data with quality controls. Regional residences contained 108 Bq/m3 geometric mean radon (min < 15 Bq/m3; max 7,199 Bq/m3), with 17.8% ≥ 200 Bq/m3. Pairwise analysis reveals that short term radon tests, despite wide usage, display limited value for establishing dosimetry, with precision being strongly influenced by time of year. Regression analyses indicates that the modern North American Prairie residential environment displays exceptionally high and worsening radon exposure, with more recent construction year, greater square footage, fewer storeys, greater ceiling height, and reduced window opening behaviour all associated with increased radon. Remarkably, multiple test approaches reveal minimal winter-to-summer radon variation in almost half of properties, with the remainder having either higher winter or higher summer radon. This challenges the utility of seasonal correction values for establishing dosimetry in risk estimations, and suggests that radon-attributable cancers are being underestimated.

Highlights

Human-made buildings can artificially concentrate radioactive radon gas of geologic origin, exposing occupants to harmful alpha particle radiation emissions that damage DNA and increase lung cancer risk
We analyzed the radon potential of the Western North American Prairie Region using the US Geological Survey Data Series 424 as a base[27]
Comparison to global radon levels recently compiled by Gaskin et al.[9] indicates the 1,313,748 km[2] survey region encompasses one of the most radon-exposed large populations mapped to date (Fig. 1D)

Summary

Introduction

Human-made buildings can artificially concentrate radioactive radon gas of geologic origin, exposing occupants to harmful alpha particle radiation emissions that damage DNA and increase lung cancer risk. The International Agency for Research on Cancer lists radon as a category 1 carcinogen, meaning it is unequivocally known to cause human and animal cancers[1] Ionizing radiation such as alpha particle radiation is measured in Becquerels (Bq) that represents one radioactive decay event per second. There are three factors needed to incur hazardous radon exposure: (i) a rich geologic source and pathway (upwards) for radon, (ii) environmental design metrics that actively draw up and concentrate radon and (iii) essential or elective human behaviour that prolongs exposure or increases radon concentrations These latter two variables are potentially modifiable and are of interest in terms of exposure reduction. Radon dosimetry data was coupled to geospatial analysis, an interrogation of how built environment metrics and associated behaviours correlate with radon levels and, within a subset of regional buildings, an evaluation of multiple modalities of radon testing

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Results

Conclusion