The Minnesota Department of Health has released a map showing the prevalence of an invisible cancer-causing gas throughout the state.
The surgeon general says radon is the second leading cause of lung cancer in the country and is linked to about 21,000 deaths a year. Smoking is the number one cause and the Centers for Disease Control and Preventions says it's linked to 480,000 deaths.
The Department of Health did a study on radon levels in homes throughout the state from 2010 to 2014.
It tested 86,000 properties and found that two in five homes have levels of the gas. The department put together a map showing its findings.
According to the map, southwestern counties – like Rock and Redwood – have the most properties with high radon levels. Most southern and western counties also have high levels.
What is radon, anyway?
Radon is a colorless, odorless gas that occurs naturally in the soil.
The American Cancer Society says as radon forms in the soil, it begins moving upwards into air and water.
High levels of the gas can build up if it gets into buildings – such as houses – via gaps and cracks.
Since it comes up from the ground, most radon is present in basements or crawlspaces – whatever is closest to the soil. And people who spend a lot of time there are most at risk for getting cancer related to radon.
Levels also tend to be higher during winter months because heating systems can draw the gas up, into the home.
Because you can't see or smell radon, you need to get a special test to find out if your building has it. And if your levels are above four picocuries per liter (pCi/L), the state recommends getting your home mitigated.
The department says the average cost to get a home mitigated is $1,500.
Radon in Minnesota
Minnesota has particularly high levels of radon due to its geology and cold climate, health officials say.
The average level in the state is 4.6 pCi per liter. Meanwhile, the U.S. average is 1.6 per liter.