DES MOINES, Iowa (AP) — Builders in Iowa would be required to install radon mitigation systems in new homes under legislation that has won approval in an Iowa Senate committee. The bill moved out of the State Government Committee on Wednesday. Under the proposal, new homes must be built with radon mitigation pipes. If the homeowner discovers radon, they can add a fan to use the system.

Radon is a colorless, odorless gas that can leak through cracks in building foundations. The U.S. Environmental Protection Agency calls radon the second-leading cause of lung cancer in the U.S. The agency also says Iowa’s 99 counties are in the agency’s highest risk zone for exposure.

A similar bill was approved by the Democratic-majority Senate two years ago but failed to advance in the Republican-controlled House.