Indoor radon survey in Greenland and dose assessment.

Indoor radon and its decay products are the primary sources of the population's exposure to background ionizing radiation. Radon decay products are one of the leading causes of lung cancer, with a higher lung cancer risk for smokers due to the synergistic effects of radon decay products and cigarette smoking. A total of 459 year-long radon measurements in 257 detached and semi-detached residential homes in southwest and south Greenland were carried out, and a dose assessment for adults was performed. The annual arithmetic and geometric means of indoor radon concentrations was 10.5 ± 0.2 Bq m-3 and 8.0 ± 2.3 Bq m-3 in Nuuk, 139.0 ± 1.0 Bq m-3 and 97.3 ± 2.1 Bq m-3 in Narsaq, and 42.1 ± 0.7 Bq m-3 and 22.0 ± 3.1 Bq m-3 in Qaqortoq. Arithmetic and geometric mean radon concentration of 79.0 Bq m-3 and 50.3 Bq m-3 were estimated for adult, person-weighted living in south Greenland. The total number of detached and semi-detached residential homes where indoor radon is exceeding 100 Bq m-3, 200 Bq m-3, and 300 Bq m-3 is 37 homes (15.0%), 13 homes (5.2%), and 8 homes (3.2%), respectively. A positive correlation between indoor air radon concentrations and underlying geology was observed. The indoor radon contribution to the annual inhalation effective dose to an average adult was 0.5 mSv in Nuuk, 6.5 mSv in Narsaq, 2.0 mSv in Qaqortoq, and 4.0 mSv for south Greenland adult person weighted. The estimated annual average effective dose to adults in Narsaq is higher than the world's average annual effective dose of 1.3 mSv due to inhalation of indoor radon. Cost-efficient mitigation methods exist to reduce radon in existing buildings, and to prevent radon entry into new buildings.

Rising Canadian and falling Swedish radon gas exposure as a consequence of 20th to 21st century residential build practices.

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/m3), 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/m3) versus Swedish equivalents (28 Bq/m3). 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/m3 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.