Concerns about radon and the possibility of related lawsuits have prompted some Washington area home builders to take steps to prevent the cancer-causing radioactive gas from becoming a problem in new houses.

Frank Bond, senior vice president of Kettler Bros. Inc., said his company has been installing subfoundation ventilation systems in all of its new homes for the past three months. The system, which consists of perforated pipes placed in four-inch-deep gravel beds under basement floors that connect to an exhaust pipe leading to the roof, is designed to collect any radon under the foundation and vent it outside, he said.

A homeowner who tests the house after he moves in and finds elevated levels of radon can install a fan that will help take even more gas from the soil.

Radon, a colorless, odorless gas produced by the breakdown of uranium deposits in the soil, usually seeps into a house through cracks in the basement floor and walls.

Kettler Bros. is not the only builder installing radon-reduction systems in its homes or planning to do so in the near future. NVRyan Homes has been installing unfinished subslab ventilation systems in all its new homes since Jan. 1. West Homes Inc. started two months ago. Winchester Homes President D.T. Noakes said his company is examining a number of options and probably will begin installing subslab ventilation systems within 90 days.

C-I Mitchell & Best Co., another Washington builder, has been installing a more elaborate system since July 1 that consists of a subslab system, extensive basement sealing and the rough-in for an air-to-air heat exchanger that takes air from the outside, heats or cools it, then pumps it through the house for additional ventilation.

However, not all builders are convinced of the need for such devices. Ron Lethbridge, a vice president of production for Porten-Sullivan, said his company isn't planning to put such systems in its new homes.

"We don't feel it's necessary," he said. "We can't see how we can be possibly responsible. It's not a code requirement in any of the jurisdictions." Lethbridge said Porten-Sullivan tests the ground for radon before building. "We haven't built in areas that have had a problem with radon so far," he said.

The decision by some builders to install such systems comes amid growing public concern about radon. The U.S. Environmental Protection Agency recently found that more than one-fifth of the houses it checked in a recent 10-state study contained potentially dangerous levels of the radioactive gas, which is estimated to cause between 5,000 and 20,000 lung cancer deaths a year and is believed to be the leading cause of lung cancer among nonsmokers.

Fairfax County's health department recently reported that more than one-third of the houses it tested had levels above EPA-recommended guidelines of four picocuries per liter, or the equivalent of smoking eight cigarettes a day. Newer houses are more likely to have radon problems because they are better insulated and cut down on air infiltrating from the outside, which allows the gas to accumulate inside.

Builders have not been immune to concerns about radon. Bond said Kettler Bros. recently lost four sales to would-be buyers who wanted to test homes for radon before settling on them. Kettler, like other builders, does not permit presettlement radon tests because such tests "don't mean anything," Bond said. Bob Mitchell, president of C-I Mitchell & Best, said that 20 percent of prospective buyers his company talks to ask about radon.

Dave Murane, an environmental scientist in EPA's radon division, said short-term testing merely shows abnormally high levels. Because radon levels fluctuate daily and seasonally, Murane said only testing at different times of the year can determine long-term exposure.

Installing finished or unfinished subslab ventilation systems, which have proven to remove 99 percent of the radon in existing houses, and other radon reduction methods are an attempt by builders to allay such fears.

"The bottom line is the homeowner's peace of mind," said Terry Riley, marketing services manager for Ryan Homes.

Bond said builders cannot control where radon is, "but if five years down the road a homeowner finds a problem, a homeowner can put a fan into the {exhaust} pipe, create a strong suction underneath the slab" and solve the problem easily and inexpensively.

Bond said subslab ventilation systems cost only $300 to $400 to install during construction. Riley estimated that installing a fan would cost a homeowner between $150 to $1,000. By comparison, adding a subslab system after a house is constructed can cost $2,500 or more, according to Dave Saum, president of Infiltec Corp. of Falls Church, which retrofits existing homes with radon reduction systems.

Builders also are worried about being sued if radon becomes a problem in their homes. "It's a known problem that needs to be addressed," Mitchell said.

He said installing radon reduction systems and using other construction techniques that prevent the gas from accumulating should help a builder defend itself in a lawsuit by showing that the company took reasonable precautions to prevent a problem.

"We want to remove the bullet from their gun," Bond said.

West said as more would-be buyers become aware of radon, reduction systems could become a good selling point. "Although it's not a big point right now, it will become more of a selling point down the road," he said