(AP) — High levels of cancer-causing radon have been found in some Pennsylvania water wells, adding to the much bigger threat faced by homeowners from airborne sources of the radioactive gas.

Radon is the second-leading cause of lung cancer after smoking. It’s a serious problem in Pennsylvania, where about 40 percent of households have indoor radon levels high enough to warrant taking action to vent the harmful gas.

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Radon primarily enters a home through rock and soil, but federal researchers found high levels of radon in 14 percent of Pennsylvania water wells. Radon can be released from the water and become airborne when someone washes the dishes, takes a shower or does laundry – slightly increasing the overall radon level in the home.

Homeowners are being encouraged to test their air and water for radon.

(Copyright 2017 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.)

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