Saying that the EPA and the states had failed to protect the health of their citizens, environmental groups filed suit against the federal agency in June for missing deadlines to improve air quality in the Clean Air Act.

In suits filed in Washington, D.C., the Sierra Club Legal Defense Fund and others said the EPA had failed to force Virginia, Maryland, Pennsylvania and the District of Columbia to do more to reduce ozone pollution.

The suits specifically cite the EPA's failure to make the states develop and implement plans to reduce smog-causing emissions by 15 percent. The plans were to be completed in 1993 and implemented by this November. The SCLDF, which is leading the court challenge, called on the EPA to develop a 15 percent reduction plan for the states.

But while the suit specifically addressed the 15 percent issue, attorney Howard Fox faulted state and federal governments for their repeated failures to reduce ozone pollution since the original Clean Air Act was passed in 1970.

That law required states to meet all clean air standards by 1975, Fox noted. Instead, he said, children born that year have "lived their whole lives breathing unhealthy air."

"It was the states' failure that forced Congress to step in initially in the 1970 Act, and it is the states' failure to meet deadline after deadline for cleaning the air - first in 1975, 1982 and 1987 - that brought us to where we are today," he said.

In the face of public resistance, state agencies and the EPA have backed off some planned clean air measures to control ozone pollution, such as requirements for a more extensive vehicle emissions testing program and plans to promote car pools at businesses. A number of bills have been introduced in Congress to weaken parts of the Clean Air Act.

But Fox disputed that moves to protect air quality would provoke a greater backlash. "We're just upholding the law that has been written and which is designed to protect the public health and the environment," he said. "And that's not something that's going to raise any legitimate objections from anyone."

But some expressed doubt that the states acting on their own, or the EPA acting for them, could develop plans that would resolve the local ozone problem.

"No one state, no one city can solve air quality problems. What affects Washington can affect Baltimore. What affects Baltimore can affect Philadelphia. What affects Philadelphia can affect New York," said Jackie Seneschal, the air quality specialist for the Metropolitan Washington Council of Governments. "It can't be done on a case-by-case basis, it has to be a cooperative effort."

Recently, the 37 states east of the Rocky Mountains, along with the EPA, have formed the Ozone Transport Assessment Group, which is attempting to determine control strategies that would bring the whole region into compliance with the federal ozone standard.

Such a regional approach is needed, they say, because nitrogen oxides (NOx) - one of the chief contributors to ozone - emitted in one location can drift hundreds of miles, contributing to ozone problems farther downwind.

NOx is also a major source of pollution to the Chesapeake Bay. Between 20 percent and 30 percent of all the nitrogen entering the Bay is thought to result from air pollution. In the Bay, nitrogen stimulates algae blooms which deteriorate water quality and aquatic habitats.

Other groups joining the action included the American Lung Association of Northern Virginia, the Washington chapter of Friends of the Earth, and Urban Protectors, a local environmental group.