Why the Fuss About VI When We Have Such a Radon Gas Problem?

Ten years ago this month EPA issued is draft Vapor Intrusion Guidance that altered the approach to site remediation. The guidance was issued following a couple of high profile sites where relatively low concentrations of volatile organic compounds in groundwater had apparently impacted indoor air in a large number of residences. These cases suggested the vapor pathway was far more complex than previously thought and that regulators had been underestimating the risks posed from vapor intrusion.

While the regulatory attention on vapor intrusion is certainly warranted but this focus is occurring at a time when the EPA budget is slashing its budget for radon gas-which arguably poses a far greater risk than vapor intrusion. Another irony is that EPA has leaned heavily on the large body of radon gas studies to gain better understanding of the vapor intrusion pathway.

In 2003, EPA updated its estimates of lung cancer risks from indoor radon based on a 1999 report of the National Academy of Sciences “Biological Effects of Ionizing Radiation (BEIR)” Report. Working with Science Advisory Board (SAB), the agency estimated that annual lung cancer deaths from radon are about 21,000 (with an uncertainty range of 8,000 to 45,000. Radon is second leading cause of lung cancer after smoking which means it is the leading cause of lung cancer to non-smokers.

It should be noted that the cancer estimate was based an average exposure of 1.3 picocuries per liter (pCi/L) which is lower than the EPA 4.0 pCi/l recommended action level. According to its 2003 study, exposure to 4 pCi/L is estimated to result in 73 deaths from lung cancer out of 10,000 people who are non-smokers. For exposures at 0.2pCi/L, the risk of death from lung cancer for non-smokers is 37 out of 10,000. And for 1.25 pCi/L, the risk drops to 23 out of 10,000.

In 1988, Congress passed the Indoor Radon Abatement Act (IRAA) which set a national long-term goal that radon levels in buildings should be as free of radon as the ambient air outside of buildings. The IRRA is codified in title III of TSCA (15 U.S.C. 2661-2681). Section 310 of the IRAA authorized EPA “to issue such regulations as may be necessary to carry out” the provisions of the IRAA.

Two decades since the passage of the IRAA and despite the growing evidence of the risks posed by exposure to radon gas, EPA has not proposed any indoor radon regulations. Instead, the agency has implemented a voluntary Indoor Radon Program to promote radon awareness, testing, use of radon-resistant new construction (RRNC) techniques, and installation of radon mitigation systems in existing homes. This voluntary program has not advanced the goals of the IRRA. One might even suggest it has been an abject failure.

According to a 2008  EPA OIG Radon Report, more people are now potentially exposed to unhealthy levels of radon gas than when the IRRA was enacted. According to the report, more homes had elevated levels of radon in 2005 than anytime in history. The report said only 7% of the 6.7 million new single family detached homes constructed between 2001 and 2005 incorporated radon-resistant features.  Moreover, of more than 1.5 million new single family detached homes built in high radon-potential Zone 1 areas between 2001 and 2005, only 18.4% of single family homes were equipped with RRNC. For the period 1988 and 2005, only about 2.1 million of 76.1 million single family homes radon -reducing features.

A 2010 survey by the National Association of Home Builders (NAHB) Research Foundation indicated that 40% of detached single-family homes were constructed in EPA radon zone 1 and 17% of the homes were constructed in radon zone 2. However, only 17% of these dwellings were equipped with RRNC. For multi-family buildings, the survey found 19% of the structures were located in radon zone 1 and 16% in zone 2. Only 15% of these structures were equipped with radon-resistant construction.

EPA estimates that about 9.2 million homes constructed since 1988 have indoor radon levels above EPA’s recommended action level of 4.0 pCi/L. This does not mean that the other approximately 75 million homes are necessarily safe. Since radon gas is a carcinogen, EPA says there is no safe level of exposure to radon.

EPA developed the 4.0 pCi/L recommended action level based on a Technical Support Document for the 1992 Citizen’s Guide for Radon. The action level was developed by balancing the risk factors against testing accuracy, technological feasibility, and cost effectiveness of various mitigation measures. For example, EPA concluded that the 4.0 pCi/l action level could be achieved 95% of the time while a 2.0 pCi/l level could only be achieved about 70%.

Since there is a significant risk at levels below 4 pCi/L, EPA recommends homeowners consider “fixing” their homes when the radon level is between 2 and 4 pCi/L.  Both EPA and the U.S. Surgeon General recommend testing all homes below the third floor for radon regardless of geographic location or zone designation’

The reason the country has not made significant progress towards reducing radon gas exposure is because few state or local governments mandate radon testing, mitigation or radon-resistant construction. The most recent statistics published by EPA indicate that only 6 states have statewide RRNC Codes and these only tend to apply to buildings in radon zone 1. 18 states do not have statewide RRNC codes but may have local jurisdictions with RRNC codes. 25 States do not have statewide or local jurisdictions that have RRNC Codes. 30 states have property disclosure laws that require information about radon. RRNC techniques are included in an appendix of the International Residential Code but are considered optional.

Another factor contributing to difficulty in achieving the IRRA long-term radon goal has been the misuse of EPA’s radon zone map. The map is often used as a “risk” map or screening tool to determine if homes should be tested and/or built with RRNC. The map is not to be used in lieu of radon testing during real estate transactions. EPA intended the map to be used by State and local agencies to target their resources in higher radon-potential zones and to implement radon-resistant building codes where they were most needed. However, EPA has consistently recommended that all homes be tested for radon because this is the only way to know whether radon is at an elevated level.

While EPA agreed with 2008 OIG report that the radon exposure problem was growing worse each year, it did not agree with the OIG recommendation to notify Congress that the goal set by the statute is unachievable. Instead, EPA cobbled together yet another voluntary action plan plan with a goal of installing radon mitigation system in 30% of the homes with an elevated radon level by 2020. In addition, the plan seeks to have 100% percentage of new single family homes constructed with radon-reducing features in high-radon potential areas. HUD has also committed to prepare a plan by November 2012 that will requiring radon test results as part of its ongoing inspection protocol of public and assisted housing as the first step in conducting a baseline study of its housing stock.

Clearly, this voluntary approach is insufficient to address the risk. Without effective radon control in new homes, EPA will fail to achieve the goals of the IRRA. It is time EPA used its authority under IRRA to address the risk posed by radon gas. A good starting point would be to adopt the recommendation of the American Association of Radon Scientists and Technologists, Inc. (AARST) to mandate installation RRNC in all new homes and structural remodeling of existing homes along with post-construction sampling for homes located in radon zones 1 and 2. This approach would have the additional benefit of reducing the risk of vapor intrusion since radon depressurization systems are frequently used to mitigate vapor intrusion.

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