室内氡是美国（US）肺癌的第二大主要原因，仅次于吸烟，是非吸烟者肺癌的主要原因。了解室内氡在一年中的变化，可以确定最佳测试时间，以避免低估暴露。该研究考察了46个美国州和哥伦比亚特区（DC）建筑物13年间室内氡浓度的时间变化。在数据集中，氡浓度从3.7 Bq m-3 （每立方米贝克勒尔）到52,958.1 Bq m-3不等，整体均值为181.4 Bq m-3。大约35.4％的测试显示氡浓度高于美国环境保护局（US EPA）的行动水平4.0 pCi L-1（148 Bq m-3）或更高。通过使用总体月均氡浓度评估时间变化。1月浓度最高（203.8 Bq m-3），7月最低（129.5 Bq m-3）。室内氡月均浓度在1月、2月和10月较高，在7月、8月和6月较低。这一结果与其他研究结果一致，建议继续推广全年进行室内氡测试，强调在较寒冷月份进行测试。版权所有©2023 Health Physics Society。

Indoor radon is the second leading cause of lung cancer in the United States (US) after smoking and the number one for lung cancer in non-smokers. Understanding how indoor radon varies during the year reveals the best time to test to avoid underestimating exposure. This study looks at the temporal variation in 13 years of radon concentrations in buildings located in 46 US states and the District of Columbia (DC). In the dataset, radon concentration varies from 3.7 Bq m -3 (Becquerels per cubic meter) to 52,958.1 Bq m -3 , with an overall mean of 181.4 Bq m -3 . About 35.4% of tests have a radon concentration level equal to or greater than the US Environmental Protection Agency (US EPA) action level 4.0 pCi L -1 (148 Bq m -3 ). 3 Temporal variation in radon concentrations was assessed using the overall monthly mean radon concentration. The highest concentrations were found in January (203.8 Bq m -3 ) and the lowest in July (129.5 Bq m -3 ). Higher monthly mean indoor radon concentrations were found in January, February, and October, and lower in July, August, and June. This result is consistent with findings from other studies and suggests continuing to encourage radon testing throughout the year with an emphasis on testing during the colder months.Copyright © 2023 Health Physics Society.