Radon Is Recognized as an Indoor Air Hazard Summary

  • Last updated on November 10, 2022

Recognition of the radioactive gas radon as a dangerous indoor air pollutant led to legislation and called for widespread testing. Tests found that millions of homes in the United States were exposed to significant levels of radon concentration.

Summary of Event

Radon is a radioactive gas that is naturally occurring, colorless, odorless, and almost inert. Wherever uranium exists in rocks and soil, radium (its first decay product), radon gas, and decay products from radon will also be found. In October of 1986, Congress passed Public Law 99-499, the Superfund Amendments and Reauthorization Act Superfund Amendments and Reauthorization Act (1986) (SARA), which included Title IV, the Radon Gas and Indoor Air Quality Research Act. Radon Gas and Indoor Air Quality Research Act (1986) That act directed the Environmental Protection Agency Environmental Protection Agency (EPA) to undertake a comprehensive research program concerning indoor air. Air pollution;indoor Indoor air pollution Radon [kw]Radon Is Recognized as an Indoor Air Hazard (1980’s) [kw]Indoor Air Hazard, Radon Is Recognized as an (1980’s) [kw]Air Hazard, Radon Is Recognized as an Indoor (1980’s) [kw]Hazard, Radon Is Recognized as an Indoor Air (1980’s) Air pollution;indoor Indoor air pollution Radon [g]North America;1980’s: Radon Is Recognized as an Indoor Air Hazard[03860] [g]United States;1980’s: Radon Is Recognized as an Indoor Air Hazard[03860] [c]Environmental issues;1980’s: Radon Is Recognized as an Indoor Air Hazard[03860] [c]Health and medicine;1980’s: Radon Is Recognized as an Indoor Air Hazard[03860] Reilly, William Nelson, Neal S. Lowder, Wayne M. Nero, Anthony V., Jr.

In the mid-1980’s, governmental studies indicated that radon levels in homes and other buildings were typically four times higher than comparable outdoor levels and in some cases ten or more times higher. The high radon levels presented a serious threat to public health, far surpassing the danger from such better-known hazards as chemical wastes or nuclear power plants. Some indoor radon levels were said to be the radiation equivalent of having a Three Mile Island accident in the neighborhood once a week; some people were receiving more radiation exposure from their homes than uranium miners received in their jobs. The EPA estimated that indoor radon was responsible for as many as twenty thousand cancer deaths every year, and according to the National Academy of Sciences’ National Research Council’s Committee on the Biological Effects of Ionizing Radiation, radon caused thirteen thousand lung cancer deaths annually. These rates implied that approximately one million U.S. residents would contract lung cancer from exposure to radon and that radon ranked second only to tobacco as a cause of cancer. Indeed, radon levels in some homes were said to create a risk comparable to smoking one pack of cigarettes or more a day. The EPA estimated that radon exposure caused nearly $500 million in direct health costs and nearly $2 billion in lost economic productivity.

There was clear evidence that lung cancer is caused by exposure to 100 working levels (WL) or more of radiation from radon’s radioactive decay products, called daughters. This evidence was gathered from uranium miners during the 1940’s and 1950’s, when mines were poorly ventilated and exposures were as high as 500 picocuries per liter (pCi/l) or more. Lung cancer in the miners, which occurred at about ten times the expected rate, was attributed to the exposure to radon. Evidence for lung cancer being caused by lower radon exposure levels was inconclusive. Some studies did not find higher numbers of lung cancer in high-radon areas of the country. In one study, however, which compared individuals who had lived at least thirty years in homes with radon concentrations exceeding 1.5 pCi/l with those whose homes had lower radon levels, the results suggested that radon had caused about 30 percent of the lung cancer cases.

A billboard on the outskirts of Pruntytown, West Virginia, warns of the dangers of radon in the area.

(Jim West)

The average home in the United States had radon concentrations of about 1.5 pCi/l, which amounted to an annual radon exposure of approximately 0.3 WL. Radon exposure in this average home was thought to entail a 1-in-300 risk of developing cancer over a lifetime. It was thought, moreover, that the risk from radon exposure might be exacerbated when combined with cigarette smoking, and that smokers might be ten times more likely than nonsmokers to contract lung cancer if they were also exposed to radon.

Indoor radon exposures presented risks hundreds or thousands of times greater than those presented by most environmental pollutants. The EPA and other federal regulatory agencies often assessed cancer risks as low as one in one million; few, if any, outdoor toxic air pollutants were thought to produce lifetime cancer risks in excess of one in 10,000. Even workplace chemical exposures seldom produced risks as high as the average lifetime risk from indoor radon.

Millions of homes in the United States were exposed to significant levels of radon concentration. Of the homes studied, 21 percent were found to have radiation in excess of 4 pCi/l, the level at which the EPA recommended remedial action, and nearly 1 percent of the houses studied exceeded 20 pCi/l. In regions such as Pennsylvania and Colorado, the percentage of affected houses was even higher. Even at the recommended EPA action level, there was a lifetime cancer risk of more than 1 in 1,000. If radon exposures had been controlled as strictly as other carcinogenic environmental pollutants, the federal standard would have had to have been 0.001 pCi/l or below, in which case virtually every house in the entire nation would have exceeded the standard.


A federal program to control exposures to indoor radon was established in the 1980’s, and various states and private organizations initiated their own actions. The EPA, in cooperation with the National Association of Home Builders (NAHB) Research Center, published radon guides for builders. The agency emphasized site evaluation prior to construction and recommended construction techniques such as installing a polyethylene vapor barrier under the slab, taking precautions to avoid cracks in the slab, sealing walls and penetrations, and implementing home designs that maintained neutral pressure differentials. The agency also offered advice for postconstruction remedial actions in homes with high radon contamination. On April 20, 1989, EPA administrator William Reilly called for universal testing of radon contamination in schools. The agency allocated no money for the program, however, and state and local governments consequently did very little to address the issue.

Perhaps the EPA’s most valuable service was to establish the standard for remedial action at the 4 pCi/l level. While the standard was initially promulgated for homes built in the vicinity of uranium mill tailings, the level was subsequently widely applied to evaluate naturally occurring radon as well. This action also produced considerable criticism: Some federal agencies argued that the guideline was too low, but more critics argued that the guideline was too high and left substantial residual risks to building occupants. Compared to other environmental regulations, the guideline was low, since 4 pCi/l of radiation was the equivalent of receiving two hundred chest X rays every year. The guideline was, however, a sensible first step. Millions of homes exceeded 4 pCi/l, and thus the level could be used to differentiate between very serious indoor radon hazards that required immediate attention and those that could await more thorough consideration.

The Radon Pollution Control Act of 1988 Radon Pollution Control Act (1988) set a goal of reducing indoor radon to 0.2 pCi/l, but the act did very little to promote this lower level. Congressional concern with indoor air quality continued, however, and several states seized the initiative in trying to deal with radon contamination of housing by means of investigatory research programs, information programs, standards for radon mitigation, loan programs, construction standards or guidelines, and regulations of real estate transactions. Some of these state actions went well beyond federal efforts.

Many states devoted resources to research. Those states known to have high geological radon levels—particularly Pennsylvania, New Jersey, Florida, and Colorado—were in the forefront of contamination surveys. While surveys were an important first step to determine high radon levels, they did little to improve the situation. Moreover, some home owners worried that state measurements might be made public and lower property values. New Jersey resolved these concerns by excluding radon survey data from public records.

States also initiated programs to inform their citizens of the potential radon hazard of residential housing. In New Jersey, the Department of Environmental Protection coordinated with local authorities to provide information through a toll-free telephone number. Pennsylvania too initiated such a program and published public notices about the need for testing in high-radon areas. In July 1989, Pennsylvania’s Department of Natural Resources advised all residents to test their homes for indoor radon and promised free follow-up tests for home owners with high levels.

Some states took vigorous action to prevent future radon problems by instituting new construction standards. Florida’s Department of Health and Rehabilitative Services adopted standards for new construction in 1986, which required radon testing on new homes, schools, and commercial structures in areas known to have high radon levels. In 1988, Florida began imposing a “radon surcharge” on building permits of one cent per square foot to fund research and new building codes. New Jersey too amended its building codes in high-radon areas; a 1989 law set new construction standards. Washington State passed an indoor air-quality law that changed the building code to ensure adequate ventilation in buildings and to regulate commercial buildings and schools with indoor air contamination.

State and local associations of realtors and brokers also developed guidelines for radon contamination. Virtually all real estate transactions in New Jersey began to include a radon contingency clause that made a sale contingent on whether a house could pass a radon test; if not, the seller had to undertake corrective measures. In 1987, 80 percent of sales in northern New Jersey included a radon test of the property. The Pennsylvania Realtors’ Association recommended use of radon disclosure forms in every sale, and Rhode Island and Florida required radon disclosure notices in contracts for the sale of real estate. Many other state realty organizations initiated similar recommendations or requirements. Radon tests in real estate transactions were criticized, however, because of the limited accuracy of onetime, short-term testing.

State radon control varied widely, however. The EPA identified seven states, including Texas, that had virtually no programs to respond to indoor radon contamination. In twenty-four other states, radon control initiatives existed at a very low level, with typically only a single individual in charge of investigation and control. Fourteen other states were found to be performing investigatory studies but doing little or nothing to improve the radon situation. According to the EPA, only five states (Florida, Maine, New Jersey, New York, and Pennsylvania) had operational programs to control radon. New Jersey, New York, and Pennsylvania alone accounted for approximately 88 percent of all state funding for radon control. While these were the states with the most serious radon problems, other states with significant indoor radon contamination did very little about the problem. The California Department of Health Services repeatedly downplayed the threat of indoor radon and resisted EPA recommendations for the testing of schools; the manager of California’s Indoor Air Quality Program called the EPA’s warning of radon’s health harms “overblown” and “incomprehensible.”

Various private organizations also took action to control indoor radon contamination. The most significant of these was the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE). In addition to establishing standards for the maintenance of ventilation systems—including reducing humidity and keeping filters clean—ASHRAE adopted guidelines for indoor exposures to certain chemical contaminants. Other private organizations that became involved in trying to prevent indoor air pollution included the National Institute of Building Sciences, which studied measures to control indoor radon contamination; the National Association of Home Builders, which undertook radon research, helped develop model building codes, and trained builders in radon-resistant construction techniques; labor unions and other employee associations that became more vigilant about indoor air problems in commercial buildings; and the American Federation of State, County, and Municipal Employees and the Service Employees International Union, which informed their members of the risks of indoor air pollution.

In addition, dozens of businesses and universities cooperated to form the American Association of Radon Scientists and Technologists to provide information about the risks of radon, improve the accuracy of measuring indoor radon and the science of remediation, and inform the public. Some businesses, in particular Honeywell and American Telephone and Telegraph (AT&T), demonstrated concern for the quality of air in their workplaces. Air pollution;indoor Indoor air pollution Radon

Further Reading
  • citation-type="booksimple"

    xlink:type="simple">Cross, Frank B. Legal Responses to Indoor Air Pollution. New York: Quorum Books, 1990. Deals with the health risks from indoor air pollution, government control of indoor air pollution, and the future of indoor air-pollution control. Intended for the nonscientist.
  • citation-type="booksimple"

    xlink:type="simple">Gammage, R. B., and Barry A. Berven. Indoor Air and Human Health. 2d ed. Boca Raton, Fla.: CRC Press, 1996. A good resource for students and scientists working in the area of radon, microorganisms, secondhand cigarette smoke, combustion products, and organics.
  • citation-type="booksimple"

    xlink:type="simple">Godish, Thad. Air Quality. 4th ed. Boca Raton, Fla.: CRC Press, 2004. Provides an overview of air-quality issues, including those related to public health, pollution control, and global warming. Written for the advanced undergraduate.
  • citation-type="booksimple"

    xlink:type="simple">Hines, Anthony L., Tushar K. Ghosh, S. K. Loyalka, and Richard C. Warder. Indoor Air Quality and Control. Englewood Cliffs, N.J.: Prentice Hall, 1993. Deals with the literature and the research of the authors on the topics of volatile organic and inorganic gaseous pollutants, heavy metals, respirable particulates, bioaerosols, and radon. Scientific in nature but with many sections that can be read by the nonscientist.
  • citation-type="booksimple"

    xlink:type="simple">Leslie, G. B., and F. W. Lunau, eds. Indoor Air Pollution: Problems and Priorities. Cambridge, England: Cambridge University Press, 1992. Information on indoor air pollution for the informed nonspecialist. Should be useful for occupational health physicians and nurses, industrial hygienists, personnel and safety officers, ventilation engineers, architects, and building maintainers and operators.
  • citation-type="booksimple"

    xlink:type="simple">U.S. Environmental Protection Agency. Indoor Air-Assessment: A Review of Indoor Air Quality Risk Characterization Studies. Washington, D.C.: Author, 1991. Report aimed at a scientific audience but accessible to the nonscientist as well. Deals with radon, formaldehyde, and asbestos.

Sick Building Syndrome Is Recognized

EPA Is Charged with Regulating Toxic Chemicals

Clean Air Act Is Revised

Chlorofluorocarbons Are Banned in the United States

Manville Offers $2.5 Billion to Victims of Asbestos Dust

U.S. Congress Requires Governments to Inform the Public About Toxic Pollutants

U.S. Congress Approves More Clean Air Act Amendments

CDC Publicizes the Dangers of Secondhand Smoke

U.S. Government Facilities Must Comply with Environmental Standards

Categories: History