Potentially dangerous levels of radon have been found in seven classrooms at West Springfield Elementary School, according to tests conducted late last month for the school's PTA. One classroom tested at levels equivalent to smoking about two packs of cigarettes a day, according to guidelines set by the EPA.

Previous tests, conducted for the county, had shown safe radon levels in the schools, according to school officials. School and health officials said that the new tested levels pose no immediate health threat partly because only long-term exposure would create a problem.

Radon, a naturally occurring radioactive gas, is considered by scientists and health officials to be the leading cause of lung cancer among nonsmokers. The colorless and odorless gas, produced by the breakdown of uranium deposits in the soil, seeps into buildings via walls or foundations.

The Environmental Protection Agency recommends that corrective action be taken when more than four picocuries per liter of air are found. At West Springfield, the radon readings above four picocuries ranged from 5.4 to 21.9.

The discrepancy between the recent and previous tests may be attributed partly to the fact that the same structure can test differently from one day to the next, according to Sue Amos, vice president of Air Chek Inc., a North Carolina firm that conducted the tests and has done tests for the school system.

A well-ventilated area would tend to test low, while an enclosed room would retain the radon gas and tend to test high, she said.

According to school and health officials, the radon levels of the PTA-sponsored tests conducted over the Thanksgiving holiday do not reflect normal school conditions because they were taken when the buildings were closed for a number of days.

PTA members, dissatisfied with the county's last tests, say their results reflect more thorough testing. Members said they placed 30 test canisters around the school, while the last county test in the school used one canister in an identified problem area.

The results of the recent tests were received Thursday and have prompted a meeting tomorrow night in the school cafeteria with PTA members, school officials and possibly EPA representatives.

West Springfield Elementary was among 178 schools that the county tested between August 1986 and June. Although several schools, including West Springfield, initially had radon readings at unhealthy levels, subsequent tests showed the schools were safe, school officials said.

School system spokeswoman Dolores Bohen said Friday that she did not see any urgency to conduct immediate retesting. Bohen said the county would return to the school for follow-up testing Dec. 23, as school lets out for the Christmas holiday. "We're not going to retest just because the PTA has this," Bohen said. "We really believe we have a very manageable situation and good baseline data." West Springfield, Bohen said, already was slated for more frequent monitoring because of a previous radon reading. She said the county would continue to check other schools.

Jane Pensabene, the school's PTA president, said the county retested the one trouble spot in the school when the weather was warmer and open windows may have allowed the radon gas to escape. "To say there is no radon problem, conclusively, is just ludicrous," she said.

Air Chek was sending kits to verify the recent results, Amos said.