Radon level of 2 pCi/L: is it safe?

EPA's risk chart has a row for 2 pCi/L: about 32 lung cancers per 1,000 people who smoked and about 4 per 1,000 who never smoked, over a lifetime of exposure. The advice for the row is to consider fixing between 2 and 4 pCi/L, and reducing radon levels below 2 pCi/L is difficult.

75 Bq/m3

2 pCi/L in becquerels per cubic meter, the published figure.

50 percent

Of EPA's 4 pCi/L action level (calculated).

1.54 times

The U.S. indoor average of about 1.3 pCi/L (calculated).

EPA recommends considering a fix when the level is between 2 and 4 pCi/L. For a reading of 2 pCi/L, the steps come to this:

EPA's risk chart has a row for 2 pCi/L. It estimates how many people out of 1,000 could get lung cancer if exposed to that level over a lifetime, separately for people who smoked and people who never smoked.

2 pCi/L from a short-term kit is a snapshot of a few days. The year-round average, which a long-term test comes closer to, can land either side of it: at 2 pCi/L, the home is 2 pCi/L from the action level, 100 percent of the reading, so an ordinary swing between seasons can carry it across.

From 2 pCi/L, an active system at the low end of its typical range would leave about 1 pCi/L, under 2 pCi/L; at the high end, about 0.02 pCi/L. Our arithmetic on the published ranges, not a prediction for your house: radon levels in most homes can be reduced to 2 pCi/L or below.

2 pCi/L is the exact point where the 2 to 4 pCi/L consider-fixing range begins, so one short-term result cannot say which side of it the home sits on across a year. A long-term test, more than 90 days and through winter if you can, gives the year-round answer. If you do not fix, test again sometime in the future and after any change in how you use the lowest floor.