Mike Thibault • Owner/Inspector
Serving the entire metro and western Wisconsin
info@topnotchmn.com • 651-428-2553

Radon in Minnesota Homes

This page provides recommendations from the Minnesota Department of Health (MDH) on testing for radon in Minnesota homes and how to use test results. The goal of radon testing is to estimate the amount of radon in a home. The results can help a homeowner decide if they wish to take action to protect their health.

The recommendations reflect unique aspects of the radon levels typical in Minnesota which are affected by many factors such as climate, geology and the fact that many basements are used as living space. These may differ slightly from the advice given by some others such as the US Environmental Protection Agency (EPA).

Frequently Asked Questions

1. What is radon and why is it harmful?
2. Should I test my home for radon?
3. What does the recommended action level mean?
4. How much radon in a home is safe?
5. What Types of Testing are available?

What is radon and why is it harmful?

Radon is a naturally occurring gas that enters buildings from the surrounding soil. It is colorless, odorless, tasteless and radioactive. The amount of radon found in many Minnesota homes may pose a large risk to health. Radon is known to cause cancer in humans and is a leading cause of lung cancer in the United States , second only to tobacco smoking.

The primary concern with radon is radioactive decay, or radon decay products (RDP's).  Alpha radiation emits alpha particles, which damages lung tissue.  This occurs when alpha energy is delivered directly to the cells' DNA.  Radon Decay products have half lives of 30 minutes.  This means that radon levels will be constantly fluctuating within your home as the radon decays.

The risk to the occupants is 15 times higher for smokers.  Higher radon levels pose greater risks to the occupants and longer time exposed also adds greater risk.

Should I test my home for radon?

Yes. Testing is the only way to find out how much radon is in your home. The Minnesota Department of Health estimates that one in three Minnesota homes has radon levels above the EPA's recommended action level.

What does the recommended action level mean?

The EPA set a recommended action level for radon at 4.0 picoCuries/liter (pCi/L) as advice to the public on how to understand their test results. To use the recommended action level correctly, it should be compared to the annual average level of radon measured in a home. If the annual average level of radon in a home is above this action level, EPA and MDH recommend that steps be taken to lower it. If the annual average level of radon is between 2 and 4 pCi/L, EPA and MDH also recommend considering taking action to lower radon levels.

How much radon in a home is safe?

Any amount of radon carries some risk, even at or below the recommended action level. The risk of lung cancer increases with higher long-term average radon levels. Because it isn't possible to reduce radon to zero, the best approach is to lower it as much as possible. In Minnesota there are no regulations for radon, so people must decide for themselves how much radon they feel is acceptable in their home.

The following table shows the level of risk from radon at several different levels. These are estimates of lung cancer risk due to long-term exposure to radon. The risk estimates were adapted from the EPA's Assessment of Risks from Radon in Homes, June 2003. They show that there is no "safe" level of radon and that risk increases with higher levels of radon. The risk to smokers from radon is significantly higher than for non-smokers.

Radon Level (Annual Average)	Additional Lung Cancer Risk for People Who Have Never Smoked
20 pCi/L	36 out of 1,000
10 pCi/L	18 out of 1,000
8 pCi/L	15 out of 1,000
4 pCi/L	7 out of 1,000
2 pCi/L	4 out of 1,000

What Types of Testing are Available?

Testing for radon comes in two forms: ACTIVE and PASSIVE. Passive devices are inexpensive and can be purchased by any homeowner at most home improvement stores. They usually come in the form of charcoal canisters, which are placed in the lowest lived-in level of the home for 48 hours. After the test is complete, the canister is mailed to an approved lab where it is analyzed. The results are then mailed back to you. While this method costs less than active tests, there are some signficant drawbacks.

Let's assume your test result is 4.2 pCi/L. As we learned above, the EPA suggests improvements (radon mitigation) whenever readings exceed 4.0 pCi/L. According to the test results from this passive device, this home should be mitigated. The problem I have with this is that radon is constantly fluctuating. This means that your home could have a reading of 1.0 at one time and 6.0 at another.  Therefore, it is very difficult to determine your overall risk based on one reading.

That is why I strongly suggest active testing.   The same procedures are followed during active testing, but the charcoal canister is replaced with an electronic monitor.  Continuous Radon Monitors constantly record the radon level in the air.  When the test is complete, a printed readout shows the radon level for each of the 48 hours of the test.  This allows you to see the fluctuations within the home, so you know what the highest and lowest readings were.  The average of the 48 hours is used to determine your overall reading.