RENO — More than two decades after U.S. regulators first issued guidelines on radon infiltration into homes and buildings, the World Health Organization reports that the radon threat to human health is much more serious than previously known.

The news could be particularly significant to communities in the Sierra Nevada, rich with radon exposure from the presence of decomposing granite. Forty percent of the homes tested in South Lake Tahoe have elevated levels of radon, according to the California Department of Health Radon Database. That's at or above 4 picocuries per liter — the Environmental Protection Agency's “fix-it” standard for radon.

Two years ago, the WHO set a lower standard for fixing residential radon: 2.7 pCi/L, moving more homes into the danger zone.

Radon gas is linked to 21,000 lung cancer deaths a year, second only to cigarette smoking, according to the EPA. It is the leading cause of lung cancer deaths among nonsmokers.

The Post and Courier
Friday, December 5, 2008

Ten experts presented their lives' work to the President's Cancer Panel on Thursday in Charleston, the third of four such public meetings held across the country.

Environmental factors in cancer was this year's panel topic. Presenters strode broadly among pollutants found in the ground, air, water and products we use daily.

Panelists, who listened to the presenters and asked questions, are appointed by and report to the president. Several presenters spoke on radon, a cancer-causing radioactive gas that has largely slipped out of the public's awareness.

Radon is a colorless, odorless gas that occurs naturally in the earth and can be trapped in structures. When people breathe radon, the radioactive gas decays in their lungs, shedding particles that can trigger cancer.