Rep. Michael D. Barnes (D-Md.) received assurances in a letter yesterday from the U.S. Air Force that tests at a Gaithersburg laboratory on nerve agents designed for chemical warfare pose no health hazard to the nearby Washington Grove Elementary School, a spokesman for Barnes said.

Members of the PTA of Washington Grove Elementary School complained to Barnes after learning that Geomet Technologies Inc. was conducting tests for the U.S. Air Force. Geomet has been using the nerve agents to see if they will penetrate materials being considered for protective flight suits. The tests were being conducted under a contract with the Air Force at Geomet's laboratory, which is about 600 feet from the school.

Barnes' office sought information about the agents from the Air Force last month and received a reply yesterday. In it, the Air Force said it believed the "Geomet program for handling these agents is an excellent one," and that the facility had been investigated by the Army Chemical Systems Laboratory to make sure it met federal standards before the nerve agents were shipped there.

Although Geomet did meet the standards, the Air Force asked the investigators to determine what would happen in a "worst-case situation" in which the 1.86 ounces of nerve agents originally delivered to the lab would be spilled in a parking lot there.

The Chemical Systems Laboratory reported that in such a case the "initial effects would not be felt" outside a 200-foot zone of the agents. "Outside the 200-foot zone, all the agents would have dissipated to safe levels," the letter said, according to Barnes' spokesman