General Radon Information

Maryland specific radon and radon level information can be found throughout this site. You will be able to find information about certified radon inspectors in Maryland, as well as detailed radon level information for every county in Maryland.

Radon is a naturally-occurring radioactive gas that can cause lung cancer. Like all radioactive substances, radon decays into other substances and gives off radiation. Radon gas decays into radioactive elements that can get trapped in your lungs when you breathe. This can damage lung tissue and lead to lung cancer over the course of your lifetime. Radon is the second highest cause of lung cancer in the United States, with EPA estimating that up to 15,000 Americans die every year from long-term exposure. However, not everyone exposed to high levels of radon will develop lung cancer. The amount of time between exposure and the onset of the disease may be many years. Anyone who lives in a single family home, townhome, or ground level apartment or condominium is potentially at risk, although smokers are especially at risk, and can be up to 25 times more likely to contract lung cancer through prolonged exposure.

However, there are scientific realities which should be considered to temper the alarming nature of these statistics. As Michele Courville, the Department of Environmental Protection's Indoor Air Quality specialist, points out, there is time for everyone to learn more about radon and the actual health risks from different levels of exposure and periods of exposure. There are a variety of tests for radon, there is help available to interpret test results, and there are certified contractors available to mitigate radon levels through structural improvements, if required at all. Courville stresses that "radon awareness should focus on education, not on anxiety." Radon is a potential environmental health problem, but there are plenty of county resources available to help.

The U.S. Environmental Protection Agency (EPA) has identified areas of the United States that have the potential to produce elevated levels of radon. According to a national residential radon survey completed in 1991, the average indoor radon level in the United States is 1.3 picocuries per liter (pCi/L). The average outdoor level is about 0.4 pCi/L. Excessive radon levels have been found in all of the 50 states.

Some areas of Maryland are known to have shown high radon readings over time. Readings of over 4 pCi/L are often found in Montgomery and Prince George's County in Maryland, in addition to western Baltimore County.

The number of radon-problem houses in an area is usually in a direct proportion to the amount of uranium in the underlying soils and rocks. Granites and rocks derived from quartz-rich igneous rocks normally exhibit higher concentrations of radioactive material than quartz-deficient rocks, so areas of quartz-rich rocks can be expected to present more problems than normal. Houses built over serpentinite will have few if any problems. Houses built in other areas of the Piedmont Province, particularly those built on the zone of phyllites running through central Montgomery, western Howard, eastern Frederick and central Carroll Counties can have indoor radon values far in excess of those considered safe by the Environmental Protection Agency. The sands and gravels of the Maryland Coastal Plain, in general, have been well oxidized and most of the uranium has been leached out and carried away. Certain Coastal Plain sediments, however, contain uranium-rich phosphate beds which are resistant to oxidation, and homes built on these formations may show elevated radon values. Studies indicate that often extremely localized geologic environments, coupled with the idiosyncrasies of building construction, play a major role in those Maryland homes containing abnormal concentrations of radon.

The only way to know whether your home has elevated radon levels is to test your home. There are no physical signs to warn you of the presence of radon, and it cannot be detected with the senses. And since radon levels can vary significantly from home to home, you can't use your neighbor's test results to determine whether or not your home has a problem. Your home must be tested. Testing your home for radon can be done in about 4 days. Readings of over 4 picoCuries per liter (pCi/L) or higher should have remediation. Mitigating your home for radon problems is usually simple and relatively inexpensive, ranging in cost from $800 to $1200.