New Hampshire (my home state) is currently having an argument about what the safe level should be for indoor air radon concentrations. Radon is a fascinating environmental issue as I will explain.
The US Environmental Protection Agency (EPA) recommends (not regulates) a safe level for in-home air of 4 picocuries per liter of air (4 pCi/L). Where it exists in the ground, natural outdoor air radon levels is on the order of 0.4 pCi/L, or one-tenth the EPA recommended indoor safe level. Most in-home mitigation measures can only reduce indoor radon to about 0.5 to 1 pCi/L. EPA doesn’t want to regulate the inside of your home, so it simply offers a recommendation. The problem is that the recommended level is equivalent to a 7 in 1,000 risk of getting cancer (radon causes lung cancer). This is higher than the cancer risk level that EPA uses to trigger cleanup action at Superfund sites. In other words, the same risk EPA says is ok in your home is too dangerous for a Superfund hazardous waste site. To be fair to EPA, however, what else could they do when the outdoor level is only ten times lower?
A radiation primer: Radiation is the emission of energy in the form of waves or particles. Although radio and light waves are a form of radiation, the bad stuff is “ionizing radiation” (radiation with enough energy to break chemical bonds and break up atoms into ions) which comes in 3 forms: alpha particles, beta particles, and gamma waves, i.e., helium nuclei, electrons, and photons, respectively. When radon decays, it emits alpha particles, which get inhaled and cause cancer. The measure of alpha radiation is the Curie, which so happens to be equivalent to 37 Billion decays per second (alpha emissions, odd number/long story) of a standard radioactive form of the element Radium. A picocurie is a trillionth of a Curie, which thus equates to 1 decay every 30 seconds. Seems like not much, huh? But, according to the National Cancer Institute, radon causes up to 22,000 US lung cancer deaths per year.
This is a serious environmental problem, but there is little EPA, New Hampshire, or we can do about it because it is naturally occurring, such as in granitic bedrocks. Go here for a map of generally occurring levels in the US (Zone 1 is greater than 4, Zone 2 is 2-4, and Zone 3 is less than 2 pCi/L): http://www.naturalhandyman.com/iip/infsisters/infradon/infusaradon.html — If you live in the red zone, get tested.
Agencies in other parts of the world recommend slightly lower levels than EPA, on the order of 2.5 pCi/L, but everyone recognizes there’s not much to do about radon because it is naturally occurring. Nevertheless, it kills and if you have elevated levels in your home, you should install a mitigation system, which amounts to sucking the air out from below your basement slab and pumping it up to your roof.
Which brings us to New Hampshire, who recommends a safety level of 2 pCi/L. New Hampshire realtors are currently fighting this low level saying it’s not in line with everyone else. Shame on them and kudos to NH, who at least is trying to make your home safer while still recognizing the pragmatism of the problem. New Hampshire is sensitive to this issue because it has a lot of granite (recall it’s called “The Granite State”). The realtors want a higher level because it will make it easier to sell houses. There is nothing altruistic about their motive.
And don’t forget your drinking water. Your worst exposure from drinking water radon is when you take a shower. During a hot shower, much radon volatilizes into the shower air, which is often confined so you are getting a concentrated dose. EPA doesn’t have a drinking water radon standard by itself, but it offers a drinking water standard of 15 pCi/L (of water) for gross radiation. If you have a private well in granitic bedrock, you should have your water tested. Treatment methods of water for radon include aeration and activated carbon.
One ray of hope – although radon in a basement with underlying granitic bedrock might reach high levels (and need mitigation), air circulation in a home, even in the winter, usually means the living space air (e.g., in the living room, upstairs) is much lower. Thus if you test indoor air, test both the basement and the living spaces and you might take comfort if the level is lower above your couch.