Fairfax County school officials told parents in a meeting last night they plan to install radiation monitors today at West Springfield Elementary School, where potentially dangerous levels of radon gas have been detected.

The devices will make hourly readings of radiation levels, and, if radiation is found to remain high, Assistant Superintendent Al Hlavin said, he will recommend corrective action, which might include removing children from affected classrooms.

Tests conducted late last month for the school's PTA found the high levels of the radioactive gas in seven classrooms.

Last night, speaking to about 100 parents in the school cafeteria, Hlavin said: "Knowing what we know, it does not call for an immediate shutdown of an area."

Hlavin and a U.S. Environmental Protection Agency official were among the speakers at the two-hour session held in response to parents' concerns.

Radon is a naturally occurring gas that 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 through walls or foundations.

In addition to the continuous radiation monitors, Hlavin said, the school system plans to place two other kinds of monitors, including radon detectors similar to those used in the tests done for the PTA.

School officials said after the meeting that it was not likely that the children would be removed immediately if the monitors showed high levels. They said they would wait until more information has been gathered before they would consider such an action.

West Springfield Elementary was among 178 schools that the county tested for radon between August 1986 and June 1987. Although several schools, including West Springfield, initially had radon readings at unhealthy levels, subsequent tests showed that the schools were safe.

The EPA recommends that corrective action be taken when more than 4 picocuries of radon per liter of air are found. The PTA-backed tests showed concentrations ranging from 5.4 to 21.9 picocuries per liter.

Judy Pensabene, the school's PTA president, said the group decided to have its own tests conducted because it wanted a more thorough evaluation of the radon problem at the school. Pensabene said that the county retested one trouble spot in the school when the weather was warmer and that open windows may have allowed the radon gas to escape. She said school officials "should consider options for remediation while testing is being conducted."