It won’t be long before people around the country learn how much mercury is coming out of the smokestacks of their local power plant. The EPA has directed utilities to test how much mercury goes into the air through their plants’ smokestacks.

Mercury is a heavy metal that, with high exposure, can cause developmental problems in fetuses and delay walking and talking in children, as well as lowering scores on nervous system function tests.

Mercury is of particular concern because it persists in the environment. Mercury air emissions can end up in waterways through rainfall and runoff and “bioaccumulate,” or build up, in the food chain. It is one of 14 chemicals on the Bay Program’s “Toxics of Concern” list — those substances thought to pose the greatest risk to aquatic life in the Chesapeake.

The EPA said on Nov. 16 that the information from more than 1,400 coal-burning power plants around the country will be gathered by the agency and made available to the public, beginning in 2000. The testing must begin in January.

“Community right-to-know efforts are a hallmark program of the Clinton administration, and one of the most effective tools to solve tough environmental problems,” said EPA Administrator Carol Browner. “Putting in- formation about toxic chemical pollution directly into the hands of citizens helps them make informed decisions about how to best protect the health of their families and how to work in their communities to prevent the pollution in the first place.”

Coal-burning power plants account for a third of the mercury released into the environment each year in the United States. Mercury is not emitted by nuclear power plants or those using natural gas.

“For too long, electric power plants have not only polluted the air with mercury, but they have kept their polluting actions a secret from the public,” said David G. Hawkins, an attorney for the Natural Resources Defense Council.

The NRDC filed a lawsuit demanding that the EPA regulate mercury from power plants. Congress earlier this year directed the EPA to hold off on regulating utilities for mercury emissions until further studies can be completed on how to reduce mercury releases.

Waste incinerators that burn products containing mercury are also a large source of airborne mercury. After being released, mercury travels through the air, eventually falling into lakes and streams to contaminate fish. Forty states have fish advisories in some of their waters because of mercury contamination.

Separately, the EPA unveiled a long-term plan to deal with mercury contamination from all sources. The plan calls for emission standards for municipal, hospital and industrial waste incinerators, as well as programs designed to reduce the amount of mercury in the waste stream, so that less is burned.

While such standards have already been issued for hospital and municipal waste incinerators, they hve not yet been issued for industrial waste furnaces. In areas other than the power plants, the agency sees the best results in trying to reduce mercury use, so less has to be disposed of.

“Generally, EPA will look to voluntary rather than regulatory approaches to reduce mercury use,” the agency said.

Environmentalists, meanwhile, said the EPA’s mercury action plan, though a step forward, fell short of what is needed.

The federal emission standards for hospital and municipal waste were weaker than standards proposed by New England governors, said Michael Bender, executive director of the Mercury Policy Project, an environmental coalition based in Vermont.

“The EPA’s plan does not do enough,” Bender said. He said the federal government 20 years ago announced a goal to eliminate mercury emissions, but the amount going into the environment continue to increase.