In all the 290 research dwellings, 45 (23%) have indoor radon level above 150 Bq/m 3, a limit value of indoor radon concentration suggested by U.S. Environmental Protection Agency.

• 在进行调查的 1 90个居室中 ,有 4 5个 ( 2 3%25 )居室室内氡浓度超过美国环境保护局制定的 1 4 8Bq/m3室内氡浓度的上限值。