The World Health Organization in Geneva called today for greater caution in levels of acceptable radon gas in homes.

Bill Angell of the U of M’s College of Design and Extension played a crucial role in setting the new guidelines, which say that radon gas levels in homes should be lowered to about one-third of the previously recommended threshold.

The Environmental Protection Agency ranks Minnesota fourth highest in the nation with dangerous levels of radon -- which is the second leading cause of lung cancer and the primary cause in people who never have smoked. Some 60 percent of Minnesota homes have radon gas concentrations higher than WHO’s new recommended threshold for action, and an additional 400,000 homes in the state will need mitigation.

Stricter guidelines were needed because of "growing evidence of the serious toxic risk posed by indoor radon," Angell said in a U of M release.

While the lung cancer risks of high-dose radon (typically found among uranium miners) had been known for many years, new studies confirm that low levels of exposure to indoor radon contribute substantially. If the new guidelines are followed, about 9,000 fewer Americans -- including several hundred Minnesotans -- could be saved from lung cancer deaths each year, Angell said.

"Our risk is higher in Minnesota partly due to our geology — soil in the Upper Midwest contains widespread uranium — and partly due to having our homes closed up so much of the year to stay warm," he said.

More information is available at these sites:

WHO Handbook on Indoor Radon: A Public Health Perspective

University of Minnesota Extension Housing Technology resources

WHO Radon website

U.S. Environmental Protection Agency

Minnesota Department of Health

To order low-cost radon test kits, go here.