4.0 is formally specified as warning line.
But actually, long exposure to radon level at 2.0 can be problematic too.
順便提醒大家買房注意查radon, 美國non-smoker 1st reason for lung cancer
myenglishid (2009-07-01 20:48:57) 評論 (1)4.0 is formally specified as warning line.
But actually, long exposure to radon level at 2.0 can be problematic too.