(ABC 6 News) — Radon is often overlooked because we can’t see or smell it, but even still, it poses a risk.

Radon is a radioactive gas that can cause cancer, but most Minnesota schools don’t even know whether or not they have it.

In fact, the Minnesota Department of Health says less than half of all public schools are testing for radon. In Olmsted County, about 75% of schools run the test.

If you are concerned about your child’s safety, there are a few things you can do.

“Schools have health and safety coordinators and facilities staff that you can contact and ask questions, and they should be able to tell you if a particular school has been tested and what the results are,” said Daniel Tranter of the Minnesota Department of Health.

Radon testing is expensive, and the results must be reported so it may be smart to start with your own home first.

The EPA says no level of radon is safe, but levels of four PCIs per liter are considered high and seeing a doctor is recommended.