g******4
发帖数: 6339 | 1 What is a safe level of radon gas?
This is the simpler of the two questions. A safe level of radon gas is no
radon gas. Radon gas is a carcinogen which causes lung cancer. The US EPA
has put it plainly, stating, "Any radon exposure has some risk of causing
lung cancer. The lower the radon level in your home, the lower your family's
risk of lung cancer." The average person receives a higher dose of
radiation from the radon levels in their home than from their combined
exposure to all other radiation sources, natural or man-made.
Radon gas is a naturally-occurring byproduct of the radioactive decay of
Uranium in the soil. Depending on your geographic location, the radon levels
of the air you breathe outside of your home may be as high as 0.75 pCi/L.
The national average of outside radon levels is 0.4 pCi/L and it is
estimated by the National Academy of Sciences that outdoor radon levels
cause approximately 800 of the 21,000 radon induced lung cancer deaths in
the US each year.
Your risk of lung cancer increases substantially with exposure to higher
radon levels. Lung cancer risk rises 16% per 2.7 pCi/L increase in radon
exposure. (World Health Organization, 2009)
Studies show that radon is the primary cause of lung cancer among people who
have never smoked. However, the absolute numbers of radon-induced lung
cancers are much larger in people who smoke, or who have smoked in the past,
due to a strong combined effect of smoking and radon.
What is an acceptable level of radon gas?
Radon Act 51 passed by Congress set the natural outdoor level of radon gas (
0.4 pCi/L) as the target radon level for indoor radon levels.
Unfortunately two-thirds of all homes exceed this level. The US EPA was
tasked with setting practical guidelines and recommendations for the nation.
To this end, the US EPA has set an action level of 4 pCi/L. At or above
this level of radon, the EPA recommends you take corrective measures to
reduce your exposure to radon gas.
This does not imply that a level below 4.0 pCi/L is considered acceptable,
as stated in the BEIR VI study. It is estimated that a reduction of radon
levels to below 2 pCi/L nationwide would likely reduce the yearly lung
cancer deaths attributed to radon by 50%.
However, even with an action level of 2.0 pCi/L, the cancer risk presented
by radon gas is still hundreds of times greater than the risks allowed for
carcinogens in our food and water. | g******4
发帖数: 6339 | 2 建议对策 - 为您的孩子的健康, 测试你房子的氡气 |
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