William and Mary researchers find elevated radon levels in Williamsburg homes

On the Environmental Protection Agency’s map of radon risks, Virginia’s coastal plain is a sunny shade of yellow.

Yellow is the best color to be on the radon map. Yellow is assigned to those areas that in 1993 the agency determined had the lowest potential for high levels of radon, a naturally occurring radioactive gas linked to lung cancer, to be detected in homes.

But yellow can also be deceptive.

Earlier this month, researchers at William & Mary announced the discovery of an apparent new hotspot for residential radon around Williamsburg, a city firmly in the coastal plain.

Using data from roughly 200 homes in the area tested for radon, geology Professor Jim Kaste and research associate and former Virginia state geologist Rick Berquist found that between 15 and 39 percent of the homes they tested had radon at levels above four picocuries per liter of air, the concentration of radioactivity chosen by EPA as its “action limit” for the gas. Furthermore, the higher levels appear to be connected to a geologic feature known as the Yorktown Formation.

Berquist, who has been collecting data on radon in the region since 1989, said that he’s known for decades that there was likely “an issue with radon in homes built on the Yorktown” but until recently didn’t have sufficient data to prove it.

Now, “I’m pretty confident about what we’re doing,” he said. “We’re living in a time where if you see something, say something. But you don’t say something unless you know what you’re talking about.”