AUGUSTA — The Maine Center for Disease Control and Prevention said Friday it’s providing a new online tool to help reduce residents’ chance of radon exposure.

The new data tool summarizes radon test results at the town, county and state levels and provides eight years of household survey data about testing, the agency said.

It said survey data show that only about a third of Maine households have tested their homes for radon.

Radon is a colorless, odorless gas that is the second-most common cause of lung cancer, and the leading cause of lung cancer in nonsmokers.

Some communities in southwestern Maine and in Hancock and Aroostook counties have elevated levels of radon in more than half the households, said Maine CDC director Nirav Shah. He said testing and mitigation are readily available in the state.