In Wisconsin, radon is common — and in high concentrations, it can be hazardous.
The state Department of Health Services is raising awareness of the potential impact of exposure, encouraging homeowners, renters, building owners and schools to test for the colorless, odorless radioactive gas.
Radon is the second-leading cause of lung cancer, behind smoking. About 962 people in Wisconsin have lung cancer from radon currently, DHS said.
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“The good news is that testing is simple and fairly cheap,” said Amanda Koch, the DHS radon program manager. “Really, anyone could do it.”
Wisconsinites can get tests for around $30 from hardware stores, or cheaper from their closest Radon Information Center. DHS recommends people test their homes at least once every two years.
Radon occurs naturally and enters buildings from the ground, where it can concentrate indoors.
“This especially happens during the cold winter months, when homes are being heated and doors and windows are kept shut,” Koch said.
If the basement is occupied for at least seven hours a week, that’s where people should test first, DHS said.
“The lowest level of that house…or building is usually where levels are the highest,” Koch said.
The U.S. Environmental Protection Agency recommends radon mitigation for levels at or above 4 picocuries per liter. At that level, the risk of cancer is elevated and is much higher for smokers, according to the agency.
Contractors can measure and fix radon exposure. If Wisconsinites test and find high levels, they should get a qualified professional to install mitigation, DHS officials said.
The gas comes from uranium decaying in rocks or soil naturally. Parts of the state tend to have more because of the geology of the area, including around Marathon County, Koch said.
“We tend to see more radon tests come back with high levels in that area because of the particular geologic makeup,” she said.
Other regions with more radon include the Driftless Area, Door County and parts of southern Wisconsin, she added.
“However, it’s just really important to understand that high radon has been found in every county in Wisconsin,” Koch said. “We encourage everyone to test no matter where they live.”
Children can be more vulnerable to radon exposure.
“Children have smaller bodies, smaller lung sizes.” Koch said. “If there’s high radon in a building, they’re going to be more exposed. They’re going to have a greater dose, so to speak, compared to an adult.”
In 2023, state officials ruled that licensed child care centers had to test for radon and mitigate unsafe levels.
Schools should also test for the gas every five years, or following construction, DHS said.
Don’t panic
Chronic radon exposure is the problem, Koch said.
“Radon is ever present, actually, in our atmosphere, in our environment, it is out there,” she added. “It is only when levels are high and are building up inside your home that it is a concern.”
About 21,000 people die from radon-induced lung cancer every year, the EPA estimates.
How to test
Radon test kits measure levels in a building over time, from days to weeks to months. The EPA recommends a days-long test, followed by a longer one if the radon level is at or above 4 picocuries per liter.
Some Wisconsin Radon Information Centers offer $10 tests that can be ordered by phone.
Tests should be placed in the lowest lived-in level of a building (the first floor, or basement — if it’s frequently used). Then, the test should be sent to a lab to get results.
If the test reveals high levels, DHS recommends locating a certified contractor through the National Radon Proficiency Program or the National Radon Safety Board.
Mitigation costs about $1,500 on average, Koch said.
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