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Rising Canadian and falling Swedish radon gas exposure as a consequence of 20th to 21st century residential build practices
Selim M . Khan 1 , 2 , Dustin D . Pearson 1 , Tryggve Rönnqvist 3 , Markus E . Nielsen 1 , Joshua M . Taron 2 * & Aaron A . Goodarzi 1 *
Radioactive radon gas inhalation is a major cause of lung cancer worldwide and is a consequence of the built environment . The average radon level of properties built in a given period ( their ‘ innate radon risk ’) varies over time and by region , although the underlying reasons for these differences are unclear . To investigate this , we analyzed long term radon tests and buildings from 25,489 Canadian to 38,596 Swedish residential properties constructed after 1945 . While Canadian and Swedish properties built from 1970 to 1980s are comparable ( 96 – 103 Bq / m 3 ), innate radon risks subsequently diverge , rising in Canada and falling in Sweden such that Canadian houses built in the 2010 – 2020s have 467 % greater radon ( 131 Bq / m 3 ) versus Swedish equivalents ( 28 Bq / m 3 ). These trends are consistent across distinct building types , and regional subdivisions . The introduction of energy efficiency measures ( such as heat recovery ventilation ) within each nation ’ s build codes are independent of radon fluctuations over time . Deep learning-based models forecast that ( without intervention ) the average Canadian residential radon level will increase to 176 Bq / m 3 by 2050 . Provisions in the 2010 Canada Build Code have not significantly reduced innate radon risks , highlighting the urgency of novel code interventions to achieve systemic radon reduction and cancer prevention in Canada .
Lung cancer in people who have never smoked is now the 7th leading cause of cancer-linked death on Earth , and its prevalence is increasing 1 – 5 . This is driven in large part by bombardment of lung cells with alpha particle ionizing radiation through the repetitive inhalation of radioactive radon-222 ( 222 Rn ) gas and its decay progeny such as polonium-218 ( 218 Po ) and polonium-214 ( 214 Po ), all of which are potent alpha particle emitters 7 , 10 – 16 . Alpha particle ionizing radiation from radon damages lung cell DNA to produce genetic mutations that promote cancer , and are classified as a category 1 carcinogen by the International Agency for Research on Cancer 6 – 8 . In addition to being the principal cause of lung cancer in North American and European never-smokers , radon is also a major driver of lung cancer in smokers and causes many thousands of new diagnoses and related deaths per year 3 , 6 , 7 , 9 – 16 . Alpha particles from radon and its progeny are measured in Becquerels ( Bq ) per cubic meter ( m 3 ), equivalent to one particle emission per second per cubic metre of air . There is an additive 16 % increase in relative lifetime risk of lung cancer for every 100 Bq / m 3 of long term radon exposure 17 , 18 .
It is important to acknowledge that prevalent , unsafe radon exposure is a relatively recent , human-made problem rooted in the design of our built environment . Indeed , although radon is emanated by most of the Earth ’ s subsurface , it dilutes naturally to low levels in the atmosphere with no evident health impacts 6 . Unfortunately , the construction and design practices of the mid to late twentieth and twenty-first century have produced urban and rural environments with residential , commercial and industrial buildings that capture , contain and concentrate radon to unnatural and unsafe levels 12 , 13 , 19 . For the majority of people , radon exposure in the residential built environment is of chief concern , as it is where most of life is spent . Indeed , the typical North American will spent 68.7 % of their life inside a residential building 20 . Understanding residential radon dynamics is key for projecting future exposure risks , as well as assessing the success of already implemented approaches to radon reduction , and to develop new , systematic approaches using a solid basis of performance-based outcomes .
1 Departments of Biochemistry and Molecular Biology and Oncology , Robson DNA Science Centre , Charbonneau Cancer Institute , Cumming School of Medicine , University of Calgary , Calgary , AB , Canada . 2 School of Architecture , Planning and Landscape , University of Calgary , Calgary , AB , Canada . 3 Radonova Laboratories , AB , Uppsala , Sweden . * email : jmtaron @ ucalgary . ca ; a . goodarzi @ ucalgary . ca
Scientific Reports | ( 2021 ) 11:17551 | https :// doi . org / 10.1038 / s41598-021-96928-x 1