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Pushing Weatherization, Feds Look the Other Way on Radon

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When using federal dollars to button up, low-income homeowners don’t get additional funding for radon mitigation. What happens next? The government isn’t telling.

By Paula Melton


Dirt basement floors in older homes can be a common cause of radon infiltration, along with air and water leaks in foundation walls.

Photo: Yew Tree House. License: CC BY 2.0.

Radon causes an estimated 20,000 deaths in the U.S. per year, according to the U.S. Environmental Protection Agency (EPA), making it the second most deadly cause of lung cancer after smoking. Most people are exposed to radon in their own homes—homes that are increasingly being tightened up through federal and state weatherization programs and other green building efforts.

Unfortunately, despite mantras like “build tight; ventilate right,” the issue of indoor air quality is still not given equal status with energy efficiency, and some of the consequences can compromise our health. There appear to be links between radon levels and weatherization—but sadly, those in a position to help us better understand those links are not sharing their research with the public.

Show us the study

EBN asked Bill Rose, senior research architect at the Illinois Sustainable Technology Center, what we currently know about the relationship between weatherization and radon levels in single-family homes.

“There are some people who know more than the others,” he answered, alluding to a 493-home study commissioned in 2010 by the U.S. Department of Energy (DOE) through its Weatherization Assistance Program (WAP) for low-income homeowners. Although the research was completed in 2011, “the results have not been promulgated,” notes Rose. “I can speculate, but I don’t want to speculate when other people know.”

William Angell, a professor at the University of Minnesota and chair of the Radon Prevention Working Group at the World Health Organization, had similar comments. “What we know based upon more than 30 years of research is that air tightening has an unpredictable impact, in general, on indoor radon concentrations,” he confirms, but he adds that “high-quality, unpublished research” suggests air-leakage rates below 0.3 air changes per hour can “dramatically increase radon concentrations.” (Air changes per hour, or ACH, refers to the number of times the interior air in a building is replaced.) Angell said a widely respected radon expert has collected data to this effect—a different research project from the WAP study—but “has been told not to publish.” Angell was unable to share further information.

Why can’t we know?

Researchers shared initial findings of the WAP study years ago, stating that full results would be available in January 2012.

The goal was to measure formaldehyde, carbon monoxide, above- and below-grade radon, and indoor temperature and humidity (as well as performing visual checks for moisture and mold) both before and after weatherization. Researchers published pre-weatherization data in December 2011 showing that 12% of the homes slated for weatherization had radon levels above the EPA action level of 4.0 picocuries per liter (pCi/L) based on short-term tests; the vast majority of homes were below 1.0 pCi/L. Although post-weatherization testing was conducted just a few weeks after the baseline testing, those follow-up results have never been published.

It’s hard to blame DOE for not wanting to release the data, suggests Angell. “There are no funds available for mitigation,” he says, but the WAP program does sometimes provide funds for pre-weatherization radon testing. “The tragedy of that is, you help people find out they have a problem” but cannot help them fix it, Angell argues. “It’s unfortunate because the cost of radon mitigation is actually quite reasonable.” But not having legal authority to provide radon mitigation funds, however reasonable the cost, puts DOE in a serious ethical bind.


Prior to weatherization, 12% of homes in the WAP study had elevated radon levels. Post-weatherization results were never released.

Source: Oak Ridge National Laboratory

Yet the agency isn’t delaying intentionally or indefinitely, argues Robert Adams, supervisor of the program. Adams initially told EBN that DOE would be releasing the report in December 2013; follow-up calls yielded later and later dates, most recently March 2014. What’s taking so long? DOE is working with the U.S. Environmental Protection Agency (EPA) on “whether we need an enhancement to our policy,” he explained.

WAP’s current health and safety guidance for radon requires exposed dirt to be covered with a vapor barrier and suggests that “precautions should be taken to reduce the likeliness of making radon issues worse,” including training for contractors about what these precautions are. That guidance isn’t provided in the document or on WAP’s website, though, and WAP’s radon page includes just one resource under its “Links to Training” heading. The link is broken.

What’s a homeowner to do?

Radon experts EBN spoke with were careful to point out that weatherizing is not the problem; the problem is the lack of attention given to the effects of weatherizing on air quality. “I am a total advocate of weatherization,” says Angell. “I am an advocate of air tightening. But we need to consider radon in that effort.”

Adams told EBN that WAP requires contractors to ”implement ASHRAE 62.2 [Ventilation for Acceptable Indoor Air Quality] at all times, trying to mitigate impacts of any environmental effects weatherization might cause.”

Yet Rose says that contractors and homeowners should not assume that increased ventilation will prevent a potential radon spike after weatherization. In fact, if your ventilation system is depressurizing your home, more radon may enter the building. “But radon doesn’t really lend itself to single, simple interpretations,” he adds, relating the story of a colleague who “was struggling with achieving lowered radon values in a house by doing sub-slab depressurization,” the usual method of radon mitigation. But when the colleague reversed the fans, pressurizing beneath the slab instead, “the radon dropped down to next to nothing really, really quickly. The notion that one pressure regime is the right one is really troublesome.” Stories like this make it difficult to accept at face value recommendations that conventional ventilation will cover all the bases.

“Ventilation directly tells you nothing about indoor radon concentration,” agrees Angell, who adds that another mantra—“dilution is the solution to pollution”—only works “if the pollutant has a constant source. The question you need answered is to what degree the air leakage into the house is coming from the soil versus ambient outdoor air.”

And there’s one reliable and low-cost way to find that out, he emphasizes: “It’s exceptionally important that you test for radon at least after you weatherize—preferably before and after. That is the only way you know.” Once you do know, a dedicated radon mitigation system is typically the best way to reduce radon levels.

Peter Yost, vice president of technical services at BuidingGreen (publisher of EBN), agrees with this emphasis: “You just have to test,” he says (see “When Weatherizing Increases Radon”). This testing makes sense regardless of which EPA radon zone you live in, he adds. Some geographical areas have generally lower levels of radon, but there can be wide variation along a single street in any area of the country.

What about low-income families?

None of this information directly helps homeowners who are relying on federal funding to weatherize their homes. These homeowners will likely save money on energy bills—and may even see decreases in radon if weatherization puts a stop to water or air infiltration into a basement or crawl space—but they will have to pay out of their own pockets for radon mitigation if the weatherization work increases their radon levels.

Without some kind of public assistance to address indoor air quality on an equal par with energy efficiency—or better guidance from DOE upon its release of the long-awaited report—their only other option will be to live with chronic exposure to the nation’s second leading cause of lung cancer deaths.

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March 3, 2014