A bill that passed the state Senate on Tuesday recommends schools test for radon. Exposure to radon is the leading cause of lung cancer in people who don’t smoke in the U.S.

Radon is a naturally-occurring gas that seeps into buildings from the soil. High levels of radon are estimated to cause more than 21,000 deaths every year.

The bipartisan bill would require the Indiana State Department of Health to recommend schools test for radon. Sen. Eric Bassler (R-Washington) authored the bill after hearing that many schools in Indiana don’t test for it.

“You can’t see it, you can’t smell it, you can’t taste it. So the only way to know it exists or not in a room or a building or what have you is to test for it,” he says.

READ MORE: State Offers Radon Testing At Day Care Centers In Pilot Program

But schools still wouldn’t be required to do radon testing. Bassler says he’s hesitant to impose a state mandate on local schools.

“I guess I would prefer to maybe walk before we run,” he says.

Bassler says its possible the state could consider more stringent legislation in the future. The bill regarding radon in schools now moves on to the House for consideration.

Indiana Environmental reporting is supported by the Environmental Resilience Institute, an Indiana University Grand Challenge project developing Indiana-specific projections and informed responses to problems of environmental change.