What is radon?

Radon is a naturally occurring radioactive gas that can cause lung cancer with repeated long-term exposure.  It comes from the decay of radioactive materials in the ground beneath your home and enters through openings in the building shell.  The home acts like a vacuum cleaner, sucking the gas into the home.  The EPA has set an Action Level of 4.0 picoCuries of radon per Liter of air (4.0 pCi/L) as the number above which some action should be taken to lower the indoor radon levels. 

Is the Action Level for short-term exposures?

No.  It is important to realize that this number is an ANNUAL AVERAGE, not a short-term exposure.  At 4.0 pCi/L, a non-smoker would need to be exposed for 18 hours per day for a total of 70 years to have a 1 in 500 chance of developing radon-induced lung cancer.  If you smoke, the risk rises to about a 1 in 35 chance.  At higher radon levels, the risk increases as the exposure time decreases.  For example, at 40 pCi/L, a non-smoker would only need 7 years of exposure to get the same 1 in 500 risk factor.  However in all cases, long-term exposure is the key.  Beware of pitchmen who use scare tactics to tout radon as an insidious killer, make outrageous claims for the number of people killed by radon, or paint it as a short-term danger.

How dangerous is radon? 

Because it is radioactive and can lodge in your lungs, any exposure is potentially dangerous.  If you smoke, the risk is even greater.  However, the effect is cumulative over many years and short-term exposure is not generally considered harmful.  In fact, the EPA tells a homeowner that if the initial radon test level is between 4 and 10 pCi/L, do some long-term testing (90 days up to one year) with an alpha-track kit to determine your long-term exposure or annual average before you consider mitigation to reduce the radon levels. 

Unfortunately, in a real estate transaction, the long-term test option is usually not available due to time constraints, and in that case mitigation is then recommended if the initial radon test level is 4.0 pCi/L or greater.                 

Can any home have radon?

Yes.  While homes with basements have more wall and floor space exposed to the ground, allowing more radon to easily penetrate through these barriers, homes with slabs and crawlspaces can just as easily have elevated indoor radon levels.  Leaving crawlspace vents open typically does not reduce radon levels.  And because your neighbor does or does not have radon in his or her home is no indication of whether you will have radon in your home.  The EPA estimates that approximately 1 out of every 15 homes has elevated radon levels and recommends that every home in America be tested.