Survey Pinpoints Excessive Radon in Public Schools : Pollution: High levels of the radioactive gas is found in more than 70,000 classrooms in nation, but threat is considered minimal in California.

Radon levels in one of every five public schools in the United States exceed the Environmental Protection Agency’s safety standard, according to a survey outlined before a House subcommittee Thursday.

The EPA study, based on the examination of 900 randomly selected schools, projected that more than 70,000 classrooms in 15,000 schools have high levels of the odorless, colorless radioactive gas, which is believed to cause thousands of cases of lung cancer each year.

In an estimated 10,000 classrooms, the radiation levels are higher than those received by workers in nuclear power plants.

Although the readings are cause for concern, “parents and teachers should not panic,” said Rep. Henry A. Waxman (D-Los Angeles), chairman of the House Energy and Commerce Committee’s panel on health and the environment, which was told of the findings Thursday.

“Radon causes lung cancer only after years of exposure,” Waxman said. “There is no evidence that children are suffering immediate, acute illnesses in our schools due to radon exposure.”

The survey found excessive radon levels in schools in every state, but results for California were not available because the findings were not broken out by individual states. About 11 million students, the survey concluded, attend schools where radon levels may present a health problem.

However, the California Department of Health Services has conducted radon tests throughout the state. Generally speaking, radon is not believed to pose a serious health hazard in most of the state and the threat to students is believed to be minimal. Because California students are in classrooms only a limited number of hours a day, their exposure is thought to be slight.

The findings indicate that readings should be taken in first-floor classrooms in all the nation’s public schools, said Margo T. Oge, director of EPA’s Office of Radiation and Indoor Air. Oge estimated that most schools could solve their radon problems by taking steps that cost $3,000 to $30,000.

Radon is produced by the decay of naturally occurring uranium in the soil and it is estimated that chronic exposure to it causes some 14,000 cancer deaths each year. Its effects are believed to be seriously aggravated when it is coupled with cigarette smoking or exposure to secondary smoke.

Children are believed to be more susceptible than adults, the International Commission on Radiological Protection has said, estimating that exposure before the age of 20 is three times more likely to lead to cancer than exposure after age 20.

“Much attention has been devoted to the nation’s educational system, yet the indoor air that our children breathe has often been neglected,” Oge said. “Preliminary investigations indicate that there is a cause for concern about the indoor quality of our schools. This situation may compromise our children’s health and their ability to learn.”

The subcommittee hearing launched what Waxman plans as a series of sessions on environmental hazards in schools and it was designed to lay the groundwork for legislation to address the radon hazard.

California health officials said their study to date--which includes surveys of 382 elementary schools throughout the state--bolsters the view that radon is not a big problem here. Less than 1% of the classrooms had levels considered unacceptable. Santa Barbara County and northeastern Ventura County are among the areas where higher-than-acceptable levels of the gas were found.

In 1989, the Los Angeles Unified School District conducted its own survey and found radon levels that slightly exceeded federal standards in just two of 78 schools tested. The levels have since been reduced.

Still, Waxman suggested that some school systems may hold back on conducting tests out of fear that they will face heavy expenses to correct problems they find. But action should be taken, he said, especially since the tests are not costly and steps to correct unacceptably high levels are relatively inexpensive.

In some cases the problem can be addressed by simple adjustments to school ventilation systems.

Times staff writers Jean Merl and Larry Stammer contributed to this story from Los Angeles.