OFFICIALS ARE now moving with commendable dispatch to protect the public against a newly identified health hazard: asbestos-laden dust from gravel made of serpentinite, a stone found throughout the East. Some pushing by the Environmental Protection Agency was required to stir Montgomery County, where the asbestos pollution was first tracked down at a Rockville quarry last year. But now loose gravel on hundreds of county playgrounds, park areas and roads is being treated or removed. Regional parks and the National Park Service's bike trails are getting similar treatment. The Maryland air-quality bureau is trying to test the serpentinite gravel from three other quarries in the state and is considering barring any more use of the paving stone in its dustiest form.

While all this work is going on, experts are still debating how much airborne asbestos people can tolerate and whether exposure to any amount of this dangerous dust should be considered "safe." Generally, controls on airborne asbestos have been growing stronger as scientists have learned more about the cancer risks from breathing even tiny amounts of the stuff. Even so, the debates over precise health standards seem likely to go on for some time. Thus it's encouraging that instead of waiting for a definitive ruling, area agencies are taking sound initiatives to limit this insidious type of pollution and reassure the public that their roads and play areas are going to be much less dangerous than before.