Yiguang Zhu ([email protected]) and Paul Locke ([email protected]
Radon is the second leading cause of lung cancer worldwide. It seeps into homes through cracks in foundations and can accumulate to dangerous levels. Long-term exposure to elevated radon significantly increases the risk of lung cancer, making it a serious public health threat—particularly in parts of Pennsylvania, where average indoor radon levels are among the highest in the United States.
In response to this challenge, Manheim Township, Pennsylvania, enacted ordinances in 2004 requiring all new homes to be built with passive Radon- Resistant New Construction (RRNC). These measures aim to mitigate radon exposure and reduce lung cancer risk at the source. RRNC integrates specific building techniques during construction to prevent radon from entering homes, effectively reducing indoor radon levels without the need for active (ie., fan drive) mechanical systems. The establishment of these ordinances represents a forward-thinking approach to guard against a seriouspublic health hazard, especially critical in a state where indoor radon concentrations frequently exceed the Environmental Protection Agency's (EPA) recommended action level of 4 pCi/L (picocurie per liter, the common unit to measure radon concentration).
To assess the effectiveness of Manheim Township's RRNC ordinance, our team at Johns Hopkins University, in collaboration with local and state agencies, conducted a study analyzing radon levels in homes built in Manheim Township after 2004. (The Pennsylvania Department of Environmental Protection (PA DEP) Radon Division has been particularly helpful in our work,)
We obtained radon test results for these homes from the PA DEP through a data sharing agreement. In Pennsylvania, all certified radon testers and mitigators are required by law to report radon test results to the PA DEP, ensuring a comprehensive database of radon measurements across the state. By analyzing radon test results from homes before and after the RRNC ordinance took effect, we compared the radon levels to see how much they decreased.
The findings were compelling: on average, the installation of RRNC features significantly reduced indoor radon levels by 16.71 pCi/L in Manheim Township homes. This substantial decrease not only demonstrates the effectiveness of RRNC
as a preventive tool but also directly translates into a significant reduction in lung cancer risk. Research has established
a clear dose - response relationship between radon exposure and lung cancer risk: for every 2.7 pCi/L reduction in indoor radon, lung cancer risk decreases by approximately 16%, regardless of smoking status. Given the 16.71 pCi/L reduction observed in our study, the RRNC
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implementation required by the ordinances reduced the radon-related excess relative risk of lung cancer by about 99%. This dramatic decrease underscores the importance of these construction techniques in protecting public health.
While lung cancer risk is elevated in people who are active or former smokers, RRNC offers significant protection for everyone, including these two groups.Our analysisshowsthat RRNC nearly halves the cumulative risk of dying from lung cancer for nonsmokers, which is especially important for vulnerable groups like children and the elderly. For smokers, who already face a higher risk, the combination of smoking and radon exposure makes riskseven higher. In homes with RRNC, we calculatedabout a 45% drop in lung cancer risk for smokers—a significant decrease given their elevated risk.
Based on these risk reductions, we estimated the potential impact on lung cancer deaths in Manheim Township. Assuming everyone benefits from RRNC, overthe lifetime of Manheim Township's current population, around 427 lung cancer deaths among smokers and 116 deaths among lifelong nonsmokers could be avoided. This shows just how much RRNC ordinances can benefit public health in our communities. Furthermore, without RRNC, current smokers had a much higher risk of developing lung cancer compared to lifelong nonsmokers with no radon exposure. With the installation of RRNC, both current and ex-smokers experienced over a 48% reduction in their relative lung cancer risks. This substantial decrease emphasizes the significant protective effect of RRNC even among high-risk groups.
Despite the clear benefits of RRNC, its adoption remains limited in Pennsylvania and across the country. Although this technology has been around for years, widespread implementation has been hampered by the lack of mandatory regulations at the state and federal levels. Manheim Township's ordinance can serve as a model for how local governments can take the initiative in protecting their residents. In the United States, radon is associated with approximately 21,000 lung cancer deaths annually. Without proactive regulations, many communities, particularly those in high-radon areas, will remain at risk.
One of the challenges in promoting RRNC is the upfront cost of incorporating radon-resistant features into new construction. While the costs are relatively modest—usually between $500 and $2,000 per home—builders and homeowners might hesitate to invest in preventive measures for a threat they can't see. However, the long-term benefits far outweigh the costs. As more people become aware of radon's health risks, we hope that communities will see the value in investing in RRNC to protect public health.
The success of Manheim Township's RRNC ordinance in reducing lung cancer risk demonstrates how local policies, grounded in scientific evidence, can have a profound impact on public health. By mandating radon-resistant construction in new homes, the township has effectively reduced radon exposure for its residents, significantly lowering their risk of lung cancer. This case highlights the importance of proactive policymaking in addressing environmental health risks. As scientists, we're committed to adding to the growing evidence supporting the adoption of such measures. Through data-driven decisions like these, we can reduce hidden dangers and create healthier, safer communities for future generations.
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