Radon is a naturally-occurring radioactive gas. It comes from the natural breakdown (decay) of uranium, which is found in soil and rock all over the United States. Radon travels through soil and enters buildings through cracks and other holes in the foundation. Eventually, it decays into radioactive particles (decay products) that can become trapped in your lungs when you breathe. As these particles in turn decay, they release small bursts of radiation. This radiation can damage lung tissue and lead to an increased risk of lung cancer over the course of a person’s lifetime. EPA studies have found that radon concentrations in outdoor air average about 0.4 pCi/L (picoCuires/Liter). However, radon and its decay products can accumulate too much higher concentrations inside a building.

Radon is colorless, odorless, and tasteless. The only way to know whether or not an elevated level of radon is present in any room is to test. Each frequently-occupied room that is in contact with the ground should be measured because adjacent rooms can have significantly different levels of radon.

The home is likely to be the most significant source of radon exposure because people typically spend most of their time at home and radon concentrations are usually higher in homes. In Minnesota, about 1/3 of homes have radon levels above 4 pCi/L. Parents and staff are encouraged to test their homes for radon and to take action to reduce elevated radon concentrations. Upon request, MDH can provide radon test result data for specific communities (by zip code), which may help provide context and encourage people to also test their homes.

For most school children and staff, the second largest contributor to their radon exposure is their school. An EPA nationwide survey of radon levels in schools estimated that nearly one in five schools has at least one room with a short-term radon level above the action level of 4.0 pCi/L