Radon wasn't always a household word - and for some, it still isn't, although it should be.
Better not to wind up like Stanley and Diane Watras.
In 1984, before anyone knew that the radioactive gas could make its way into homes, and that parts of Pennsylvania and New Jersey are radon hot spots, Watras set off radiation alarms when he reported for work at the Limerick nuclear power plant, then under construction.
Subsequent investigation focused on his home in Boyertown, Berks County, where technicians found the highest radon levels they had yet seen in the United States - about 675 times the maximum level permitted in a uranium mine.
In a way, he was lucky. He was alerted to a problem he hadn't known he had.
Officials began testing more homes, and household radon testing became a national campaign that continues to this day.
Radon is a colorless, odorless, radioactive gas that forms during the breakdown of naturally occurring uranium in soils and rocks.
Some rocks have just a little uranium. Some contain a lot.
The radon gets into homes through openings that touch the soil. Cracks and sump pits in basements are common sources, but homes on slabs can have problems, too.
The gas presents serious health risks. Its radioactive particles can get trapped in the lungs. As they break down further and release more energy, they damage tissue.
Exposure to residential radon is the second-leading cause of lung cancer, albeit still far behind cigarette smoking, according to the American Lung Association. The best estimate by officials is that radon causes 21,000 lung cancer deaths a year in the United States.
"Never-smokers who get lung cancer are naturally asking 'Why me?' " said Kevin Stewart, director of environmental health for the American Lung Association of the Mid-Atlantic. "I know people who have put two and two together and have identified radon as the chief, if not the only, logical suspect. Since never-smokers make up more and more of the population, I expect that group to increase."
Both states aggregate household testing data, available online. (See the box with this story.)
Radon amounts are measured in picocuries per liter, and the U.S. Environmental Protection Agency advises mitigation for levels above four.
One problem area in Pennsylvania - other than the Reading Prong formation that the Watras' home sat atop - is along the Route 30 corridor in Chester County. In the zip code that includes Coatesville, the average result of 5,180 basement tests is 11.8 picocuries per liter. The maximum result was 1,122.8 picocuries per liter - roughly 280 times the action level.
Philadelphia is considered a low-risk area.
New Jersey areas with high readings include Runnemede Borough in Camden County, where one-third of 142 homes tested had levels above four picocuries per liter.
But Robert Lewis, radon program manager for the Pennsylvania Department of Environmental Protection, cautioned that results can vary widely, even in homes next door to each other.
Many people get their home tested when preparing it for sale. That, or the potential buyers do.
Even so, in New Jersey, fewer than 30 percent of homes have been tested, said Anita Kopera, supervisor of the radon section in the state Department of Environmental Protection.
Pennsylvania has no similar estimate, but "it's probably, and unfortunately, the minority of homes that get tested," Lewis said.
That's sad because testing for radon is simple and cheap - do-it-yourself kits from a hardware store cost $15 to $50.
The good news is that radon can be remediated. Most often, it involves drilling through the basement floor into the dirt under the house and installing a fan and a system of pipes that vent the radon above the roof line.
Kopera said the average price is about $1,300, although it can range from $500 to $2,500.
Not bad for eliminating a significant environmental health hazard.
GreenSpace: Radon-Testing Tips
To check test results by town (N.J.) or zip code (Pa.):
New Jersey: http://www.njradon.org/radonin.htm
Results in the same area can vary. If you are considering testing your home:
Do-it-yourself kits from hardware and home-improvement stores cost $15 to $50.
Some towns or health departments offer free kits.
To hire a professional, expect to pay $50 to $200. Both states certify contractors, so ask for credentials.
New Jersey: www.njradon.org
U.S. EPA: www.epa.gov/radon
Cancer Survivors Against Radon: www.cansar.org
"GreenSpace," about the environment and health, appears every other week, alternating with Art Carey's "Well Being" column.