Chen Jing, Bergman Lauren, Falcomer Renato, Whyte Jeff
Health Canada, Radiation Protection Bureau, 775 Brookfield Road, Ottawa, Canada, K1A 1C1
Health Canada, Radiation Protection Bureau, 775 Brookfield Road, Ottawa, Canada, K1A 1C1.
Radiat Prot Dosimetry. 2015 Feb;163(2):210-6. doi: 10.1093/rpd/ncu141. Epub 2014 Apr 19.
Radon has been identified as the second leading cause of lung cancer after tobacco smoking. (222)Rn (radon gas) and (220)Rn (thoron gas) are the most common isotopes of radon. In order to assess thoron contribution to indoor radon and thoron exposure, a survey of residential radon and thoron concentrations was initiated in 2012 with ∼4000 homes in the 33 census metropolitan areas of Canada. The survey confirmed that indoor radon and thoron concentrations are not correlated and that thoron concentrations cannot be predicted from widely available radon information. The results showed that thoron contribution to the radiation dose varied from 0.5 to 6% geographically. The study indicated that, on average, thoron contributes ∼3% of the radiation dose due to indoor radon and thoron exposure in Canada. Even though the estimated average thoron concentration of 9 Bq m(-3) (population weighted) in Canada is low, the average radon concentration of 96 Bq m(-3) (population weighted) is more than double the worldwide average indoor radon concentration. It is clear that continued efforts are needed to further reduce the exposure and effectively reduce the number of lung cancers caused by radon.
氡已被确定为仅次于吸烟的导致肺癌的第二大主要原因。（222）Rn（氡气）和（220）Rn（钍射气）是氡最常见的同位素。为了评估钍射气对室内氡和钍射气暴露的贡献，2012年在加拿大33个人口普查大都会地区对约4000户家庭开展了一次住宅氡和钍射气浓度调查。该调查证实室内氡和钍射气浓度不相关，且无法根据广泛可得的氡信息预测钍射气浓度。结果表明，钍射气对辐射剂量的贡献在地理上从0.5%到6%不等。该研究表明，在加拿大，平均而言，钍射气对因室内氡和钍射气暴露所致辐射剂量的贡献约为3%。尽管加拿大估计的钍射气平均浓度为9贝克勒尔每立方米（人口加权）较低，但氡的平均浓度为96贝克勒尔每立方米（人口加权），是全球室内氡平均浓度的两倍多。显然，需要持续努力进一步降低暴露，并有效减少由氡导致的肺癌数量。
