My radon test came back high. What now?

Confirm the number with the follow-up test EPA describes, then decide whether to fix the home. EPA recommends fixing a home at 4 pCi/L or more, and considering a fix between 2 pCi/L and 4 pCi/L, because it says there is no known safe level of radon (EPA: Radon action level). CDC states the same 4 pCi/L fix recommendation and also says there is no known safe level (CDC: Radon and Your Health).

A high first test is not the last step. If you have not taken the follow-up yet, use the steps in how to test for radon.

The Citizen's Guide uses the same indoor and outdoor averages and says Congress set a long-term goal that indoor levels be no more than outdoor levels. It says that goal is not yet technologically achievable in all cases, that most homes today can be reduced to 2 pCi/L or below, and that reducing levels below 2 pCi/L is difficult (EPA: A Citizen's Guide to Radon (2016 edition)).

Prices and contractor lists are separate from the action level. The cost figures on this page are the ones already on the cost guide.

EPA's testing steps: if a short-term test is 4 pCi/L or higher, follow up with a long-term test or a second short-term test. Fix the home if the long-term result is 4 pCi/L or more. If you used a second short-term test, consider fixing if the average of the two short-term results is 4 pCi/L or higher. If the first result is more than twice the 4 pCi/L action level, take a second short-term test immediately (EPA: A Citizen's Guide to Radon (2016 edition)).

A result close to 4 pCi/L is less certain. The Citizen's Guide gives this example: if the average of two short-term tests is 4.1 pCi/L, there is about a 50% chance the year-round average is somewhat below 4 pCi/L. EPA still says levels below 4 pCi/L pose some risk (EPA: A Citizen's Guide to Radon (2016 edition)).

The zone map does not answer this question for your house. EPA says the Map of Radon Zones should not be used to determine if individual homes need to be tested. Test no matter where you live. The map was drawn in 1993 to help governments target resources, not to clear a single address (EPA: Map of Radon Zones). The Citizen's Guide says high radon levels have been found in every state, and that a neighbor's result is not a good indication of yours (EPA: A Citizen's Guide to Radon (2016 edition)).

The Citizen's Guide says lowering high radon levels requires technical knowledge and special skills, and that you should use a contractor trained to fix radon problems. If you are considering doing it yourself, contact your state radon office first. Test again after the home is fixed, and retest about every two years (EPA: A Citizen's Guide to Radon (2016 edition)). CDC says lowering high levels requires technical knowledge and special skills, so you should rely only on a qualified professional, and test again after repairs. CDC also says reducing radon helps even when the level is under 4 pCi/L (CDC: Radon and Your Health).

EPA does not publish a single dollar total for a system. The Citizen's Guide says most homes can be fixed for about the same cost as other common home repairs, and that the cost varies with the home (EPA: A Citizen's Guide to Radon (2016 edition)). Wisconsin DHS states an average of $1,000 to $2,000 (Wisconsin DHS (revised Oct 21, 2026)). The radon mitigation cost guide uses that band as its typical installed system and lists the other primary sources beside it. That is a national range, not a bid for your house. Get more than one estimate. The quote form is on each contractor profile in the directory.

These are the agencies' statements, not a prediction for one person. EPA's health-risk page says radon is the second leading cause of lung cancer and the number one cause among people who have never smoked, by EPA's estimates. It says radon is responsible for about 21,000 lung cancer deaths every year, and that about 2,900 of those deaths occur among people who have never smoked (EPA: Health risk of radon). CDC says radon is the second leading cause of lung cancer deaths in the United States after cigarette smoke, and that EPA and the Surgeon General's office estimate radon is responsible for more than 21,000 lung cancer deaths each year (CDC: Radon and Your Health). The two wordings differ (about 21,000, and more than 21,000). Both are quoted here as published.

EPA's health-risk page reprints the Citizen's Guide lifetime tables. At 4 pCi/L, it says about 62 of 1,000 people who smoked could get lung cancer, and about 7 of 1,000 people who never smoked could get lung cancer. The page says a smoker exposed to radon has a much higher risk, and that a former smoker's risk may differ (EPA: Health risk of radon). If you have health concerns, talk to a doctor. This page cannot tell you your own risk.

The $1,000 to $2,000 range is the typical installed system already published on the radon cost guide. It is not a new estimate.