General Radon Information

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

Radon (Rn) is a gaseous radioactive element that occurs from the natural breakdown of uranium in the soil and rocks. It is colorless, odorless, and tasteless. Radon becomes a risk indoors because as it continues to break down, it emits atomic particles that upon entering the lungs can alter the DNA and increase lung cancer risk. In fact, radon is the second leading cause of lung cancer in the nation and is classified as a “Class A” carcinogen according to EPA. Radon is not known to cause asthma or any other type of respiratory distress. Radon can be tested and measured (in picocuries per liter (pCi/L) of air) and there are estimated risks to health from the exposure depending on the concentration. DHSS in conjunction with EPA recommends that if the concentration of radon is 4pCi/L or greater, then remediation should be done to lower risks. Smoking in conjunction with radon exposure greatly increases the risk of cancer.

Any home may have a radon problem from such sources as:

1. Cracks in solid floors

2. Construction joints

3. Cracks in walls

4. Gaps in suspended floors

5. Gaps around service pipes

6. Spaces inside walls

7. The water supply

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.

"Testing in Missouri has shown that 18 percent of all homes have radon levels above the level considered dangerous (4.0 picocrquies per liter of air)," said Bob Schultheis, natural resources engineering specialist, University of Missouri Outreach and Extension. "The best time to test your home for radon is during cooler weather, when it is 60 degrees or less. The house should be closed up at least 12 hours before and during the test," said Schultheis.

According to the State Geological Service, "There are more questions than answers as to where we expect high risks in Missouri." We have little scientific data where we might find high levels caused by specific geological formations. Areas of the state that might be suspect are:

* Lamont sandstone areas.

* Mountain areas in southeast Missouri.

* Southwest Missouri -- black shale (especially old mine areas).

* Oil formation areas.

* Northern half of Missouri -- black or dark shale.

Energy-efficient or poorly ventilated homes are more likely to have higher radon levels according to Schultheis. This is because radon enters the home through cracks and openings in floors and walls, and through floor drains and sumps.

Although no level of radon is considered absolutely safe, the USEPA action level for radon is 4.0 picocuries per liter of air (pCi/L). (pCi/l= picocuries per liter, the most popular method of reporting radon levels. A picoCurie is 0.000,000,000,001 (one-trillionth) of a Curie, an international measurement unit of radioactivity. One pCi/l means that in one liter of air there will be 2.2 radioactive disintegrations each minute. For example, at 4 pCi/l there will be approximately 12,672 radioactive disintegrations in one liter of air, during a 24-hour period.

Wondering whether you should mitigate your home for radon problems? You should first confirm that the levels in your home are too high. If a short-term test (2-7 days) was used, you should conduct an additional long-term test. Radon levels can vary from day to day so conducting one short-term test may not reflect the true level of your home.

If you have confirmed the levels in your home and want to fix the problem, the Missouri Department of Health and Senior Services (DHSS) has a list of mitigation specialists qualified to install mitigation systems in your home. The cost can range from $500 to $2500 depending on the size and construction of the home. Lists of mitigation specialists can also be obtained from the National Radon Safety Board (NSRB) and National Environmental Health Association (NEHA) websites. They are www.nrsb.org and www.radongas.org respectively.

For those who are building new homes, radon-resistant building techniques should be used. It is much more cost effective to prevent radon problems than it is to correct them in the future. For $350 to $500, on average, your builder can take the following four simple steps to deter radon from entering your home.

* Install a layer of clean gravel or aggregate beneath the slab or flooring system.

* Lay polyethylene sheeting on top of the gravel layer.

* Include a gas-tight venting pipe from the gravel level through the building to the roof.

* Seal and caulk the foundation thoroughly.

These construction techniques will be familiar to your builder. There is no need to hire a special contractor or architect. Many builders already incorporate some of these steps in the construction of their houses to control moisture or increase energy efficiency. In fact, radon-resistant construction techniques can be found in the 1995 version of the One-and-Two Family Dwelling Code published by the Council of American Building Officials.