Radon 101

With this post I start to explore the subject of radon. The focus of my line of inquiry is to improve understanding of the nature and hazard presented by radon gas in residential properties.

For anyone who sells real estate in central Pennsylvania radon is one of several common inspection issues. To a great extent the testing and subsequent remediation of radon in homes has become routine.

When I started selling real estate in 1995 the EPA had not yet published an “actionable level” for radon. Today the actionable level is 4 pCi/L (picocuries per liter), meaning the EPA recommends that you install a radon mitigation system for home radon levels at or above 4 pCi/L.

In 1995 we relied on a chart in the EPA radon pamphlet that estimated the increased risk of lung cancer based on the radon reading in the home and length of exposure, i.e., risk vs dosage. Buyers and sellers would negotiate over the actionable level. It wasn’t unusual to write a sales agreement specifying 10 pCi/L, 12 pCi/L, or even 20 pCi/L as the level above which the seller would install a radon system. In essence the parties were negotiating risk.

This seemed like a grown-up way to deal with this type of environmental hazard. Even at 20 pCi/L the actual risk of lung cancer is still small. For many homebuyers this incremental risk is acceptable in the context of all the other risks that we are exposed to in our daily lives. Unfortunately, as far as I am concerned, the risk vs dosage chart disappeared after the EPA published new guidelines that included its recommendation that 4 pCi/L was the actionable level. This took away a useful tool for evaluating risk. It made radon as a real estate issue cut & dry—above 4 pCi/L the seller installs a system. It almost certainly resulted in more radon systems being installed. And, not inconsequentially, it increased the cost of the typical real estate transaction.

The EPA has made the reduction of indoor radon a matter of public policy and effectively substituted its judgement of acceptable risk for the homeowner's.

Facts & figures…in Cumberland and Dauphin counties, where I live and work, the average radon levels are, respectively, 11.7 pCi/L and 13.9 pCi/L (apparently the geology of southcentral PA makes high radon likely). Over 60% of homes in these counties likely exceed 4 pCi/L radon level in the basement.

Radon testing and a radon system cost about $850 ($100 test + $750 system). In 2009 the median-priced house in my multi-list area was $162,000. Therefore radon remediation adds about ½% to the typical home purchase. This is not insignificant. Certainly it is not unreasonable to ask whether the benefit of reducing the radon concentration below 4 pCi/L is always worth this cost. What if the original reading is 4.5 pCi/L? What if the new owners don’t intend to spend much time in the basement?

There is a lot of documentation about radon available online—both consumer-oriented and academic. The EPA maintains an extensive web site, as does the Pennsylvania Department of Environmental Protection. While 4 pCi/L is the de facto standard for safe indoor air quality—it’s pre-printed on the Pennsylvania Association of Realtors (PAR) sales agreement—the EPA actually recommends homeowners ”consider” installing a radon system when the radon reading is between 2 and 4 pCi/L (what does “consider” mean here? ). By this strict standard 80% of homes in southcentral PA need a radon system. For reference the average outdoor reading is 0.4 pCi/L.

As it happens I don’t know the radon level in my own house. Several years ago I finished the basement. I spend a lot of time down there, so it’s a probably a good idea I find out (I don’t disagree with the EPA’s recommendation to test your house). To this purpose I bought a testing kit for about $7 at Home Depot. The test kit is manufactured by Pro-Lab. While I intend to discuss testing in a separate post, for the record this particular kit is a passive, short-term test using liquid scintillation technology. Tomorrow I will cap the two detectors that I placed in the basement and send them to Pro-Lab for reading.