How do I know if radon is affecting my family's health?

Radon gas has no warning signs at levels normally found indoors, and radon exposure does not produce immediate symptoms.¹ The risk for lung cancer depends on the concentration you are exposed to and the amount of time you are exposed.² Therefore, the best way to protect yourself and your family is to measure the radon concentration to see if it is above the action level.

¹ Case Studies in Environmetal Medicine (CSEM) Radon Toxicity (http://www.atsdr.cdc.gov/csem/radon/).

² No radon level is considered "safe," the risk being directly proportional to the concentration and duration of exposure: the higher the radon concentration and longer the exposure, the higher the lung cancer risk. The 4 pCi/L "Action Level" was based on current mitigation technology, which almost always can reduce high radon concentration to below 4pCi/L and to 2 pCi/L or below 70-80 percent of the time (http://www.epa.gov/radon/pubs/physic.html).

Are there biological tests for radon?

No. Radon was identified as a health problem when scientists observed that underground uranium miners who were exposed to radon died of lung cancer at a higher rate than workers who were not exposed.¹ Results of miner studies have been confirmed by experimental animal studies, which show higher rates of lung tumors among rodents exposed to high radon levels.

More recent research has focused on the effects of residential radon exposure. Scientists have measured radon levels in the homes of individuals who have lung cancer and found them to be higher than the levels in the homes of persons who have not developed lung cancer.²

¹ No radon level is considered "safe," the risk being directly proportional to the concentration and duration of exposure: the higher the radon concentration and longer the exposure, the higher the lung cancer risk. The 4 pCi/L "Action Level" was based on current mitigation technology, which almost always can reduce high radon concentration to below 4 pCi/L and to 2 pCi/L or below 70–80 percent of the time (http://www.epa.gov/radon/pubs/physic.html).

² Health effects of radon: a review of the literature, Al-Zoughool M and Krewski D, 2009, International Journal of Radiation Biology, 85:57–69 (http://www.ncbi.nlm.nih.gov/pubmed/19205985?ordinalpos=1&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_DefaultReportPanel.Pubmed_RVDocSum).

Do I have a problem?

Testing can tell you if the indoor radon concentration is high. The EPA recommends taking action to reduce radon if the concentration in a home is at or above 4 picocuries per liter (pCi/L), the unit of measurement for radon.¹ Approximately 1 in 15 U.S. homes is estimated to have a radon concentration at this action level or higher.² However, the proportion of California homes with elevated radon levels appears to be much lower. CDPH conducted a statewide study 1988–89 and found that approximately 0.8% (or 1 in 120 homes) of California homes have annual average radon levels above the EPA action level.³ Radon concentrations above 4 pCi/L have been measured at somewhat higher rates in Santa Barbara and Ventura counties and in some parts of Sierra foothill counties than elsewhere in the state.

Click here to check the predicted, average, indoor radon concentration in your California county.

Click here to see indoor radon concentrations sorted by California zip code.

Click here to check a state other than California.

In 1991–92 CDPH measured radon concentrations in selected public elementary schools in California.4 We estimated that the radon concentration exceeded 4 pCi/L in one or more classrooms in approximately 5% (or 1 in 20) of schools statewide.

¹ No radon level is considered "safe," the risk being directly proportional to the concentration and duration of exposure: the higher the radon concentration and longer the exposure, the higher the lung cancer risk. The 4 pCi/L "Action Level" was based on current mitigation technology, which almost always can reduce high radon concentration to below 4 pCi/L and to 2 pCi/L or below 70–80 percent of the time (http://www.epa.gov/radon/pubs/physic.html).

² The average radon level in U.S. homes is approximately 1.3 pCi/L (http://www.epa.gov/radon/pubs/hmbyguid.html#5.g)).

³ The Distribution of Lifetime Cumulative Exposures to Radon for California Residents, Liu KS, Chang YL, Hayward SB, Gadgil AJ and Nero AJ, 1993, Journal of Exposure Analysis and Environmental Epidemiology. 3:165–179 (http://www.ncbi.nlm.nih.gov/pubmed/8241780).

⁴ Affected schools had an average of two classrooms, with a range of one to six classrooms exceeding the EPA action level. The highest radon concentration measured in a California classroom in this study was 13 pCi/L.

Annual Average Radon Concentrations in California Residences, Liu KS, Hayward SB, Girman JR, Moed BA and Huang FY, 1991, Journal of the Air and Waste Management Association. 41:1207-1212 (http://www.ncbi.nlm.nih.gov/pubmed/1756040)