A pair of recent actions increased the likelihood that Bay restoration efforts in the next decade will be bolstered by new attempts to reign in the large amount of nitrogen that bombards the Chesapeake and its watershed from air pollution, much of which originates from outside its 64,000 square-mile drainage basin.

President Clinton, in June, endorsed most of an EPA proposal to tighten clean air standards for ground-level ozone, a key ingredient of summertime smog, and for tiny bits of soot known as fine particulates.

Though the new standards are aimed at protecting public health, they will require dramatic reductions in the emissions of nitrogen oxides-a byproduct of fossil fuel combustion and a major contributor to the Bay's water quality problems.

In addition, a group of 37 eastern states known as the Ozone Transport Assessment Group-or OTAG-last month issued a series of recommendations that included a call for reducing NOx emissions at Midwestern power plants-where much of the pollution to the Bay originates-by up to 85 percent.

Taken together, the actions amount to the largest effort to date to curb NOx emissions. Despite more than two decades of air pollution controls, nationwide NOx emissions had continued to gradually increase.

"I think they're potentially really good news," Mike Hirshfield, vice president of the Chesapeake Bay Foundation, said of the actions.

"A challenge for this region has been the inability of the EPA to come to grips with the longer range transport of air pollutants like nitrogen," Hirshfield said. "To the extent that this gives them a bit stronger legal handle through the OTAG process and a tougher air standard, that should at least in theory result in less deposition to the Bay."

About 25 percent of the nitrogen that enters the Bay stems from air pollution. While some of that originates from natural sources, the vast majority is the result of human activities, primarily the burning of coal in power plants and industries, and gasoline in cars and trucks.

Because NOx can travel hundreds of miles after it leaves a smokestack or tailpipe, the majority of what lands on the Bay and its watershed originates from outside the Bay states, according to computer models.

The new air standards should reduce NOx emissions because it is a major contributor to the lung-damaging ozone pollution that forms on hot, sunny days when NOx and other pollutants mix in the air. In addition, NOx emissions can concentrate into tiny particles which will be regulated for the first time under the new standards because they are harmful to the lungs when inhaled.

To achieve the new ozone standard, the EPA said it would implement the recent OTAG recommendations, which call for reducing emissions from Midwestern utilities-which contribute to downwind ozone problems and deposition on the Bay and its watershed- by 55 percent to 85 percent.

Merrylin Zaw-Mon, director of the Maryland Department of the Environment's Air and Radiation Management Administration and a participant in the two-year OTAG process, said the EPA would probably need to seek reductions on the upper end of OTAG's recommendations to meet the new ozone standards. "We believe, especially from a utility perspective, that it is cost-effective to require the controls," Zaw-Mon said.

Such reductions would be similar to those already being implemented in a region from Northern Virginia through Maine to reduce chronic smog problems along the East Coast. But those reductions alone are not able to to fully attain ozone standards in the East because so much NOx drifts in from the Midwest.

Similar problems exist for Chicago and a few other areas. That gave rise, two years ago, to OTAG-a group which included representatives from 37 states east of the Rocky Mountains that sought to tackle the problem of long-range NOx transport.

Although the bulk of OTAG's recommendations dealt with power plants, the group also called for a national "Low Emission Vehicle," that would emit less NOx than currently manufactured cars.

It also recommended vehicle inspection and maintenance programs in some urbanized areas where they are not presently required, and encouraged the EPA to require that new cars be equipped with an "on-board diagnostic system" that would alert drivers when the emission control system malfunctions. OTAG also said the EPA should explore new standards for diesel engines.

The EPA this summer is expected to set specific NOx emission levels for states based on OTAG recommendations. The states will have the flexibility to determine exactly how to meet those targets.

The EPA has said in the past that most areas will be able to meet its new air standards through the implementation of the OTAG recommendations and the anticipated creation of a national low emission vehicle. Still, some areas would need to make additional reductions.

The air rules will not help the Bay states meet their year 2000 goal for a 40 percent reduction in the amount of nitrogen entering the Bay because the EPA does not anticipate that pollution reductions to meet the new standards would be fully implemented until after the turn of the century.

The Bay states are seeking to reduce nitrogen and phosphorus because the two nutrients spur algae blooms which cloud the water, blocking sunlight needed by Bay grasses that provide important food and habitat for fish, crabs, waterfowl and other species. When the algae die, they sink to the bottom and decompose in a way that depletes the water of oxygen needed by fish and other species.

Although the air reductions may not help reach their nutrient goal, Bay Program officials in the past have said that such reductions could help maintain the reduced nitrogen levels once the goal is attained.

But exactly how beneficial the new air initiatives will be for the Bay won't be known until more implementation details become available.

Ozone is only a problem during the summer. If the NOx reductions are implemented only during those months-as OTAG recommended-potential benefits to the Bay would be greatly reduced.

"We're certainly going to try" to get year-round controls, Hirshfield said. But for that to happen, he said, "some combination of legal and political leverage will have to be employed."

Also, none of the actions outlined so far specifically cap NOx emissions, which means they could continue to grow over time-especially during the winter-as energy demand increases and people drive more miles.

In addition, most of the reductions being sought appear to come from power plants, but they account for only about a third of total NOx emissions. Another third comes from motor vehicles, and another third from a wide range of sources ranging from train locomotives to lawn mowers.

Before they become reality, the air standards also face stiff opposition.

Under a law passed last year, Congress has 60 days from the time the new air rules are published-expected in mid-July-to review them.

Many industry leaders, who have waged a multimillion dollar campaign to defeat the standards, are urging Congress to vote to reject them. They contend it would cost far more to implement than the $6 billion to $8 billion a year the EPA estimates and that they would produce only marginal health benefits, rather than the 15,000 lives a year that the EPA says would be saved.

"It's clearly up to Congress to prevent the EPA from inflicting this harmful proposal on the American economy," said Jerry Jasinowski, president of the National Association of Manufacturers.

Charles DiBona, president of the American Petroleum Institute, said the new pollution controls will threaten "thousands of inner-city jobs" by forcing businesses out of smog-plagued areas. He maintained the rules will not significantly improve health protection.

"The punishing new standards ... are a noose around the neck of American business," complained Thomas Kuhn, president of the Edison Electric Institute, which represents more than 200 utilities.

The standards are also opposed by a majority of governors, including Tom Ridge of Pennsylvania and George Allen of Virginia. The U.S. Conference of Mayors voted at their national convention in June to opposed the standards.

Many members of Congress sent letters to the White House urging it to reject the EPA's proposal. Several members of Congress have said they planned to introduce legislation to head off the new standards. But many observers doubt there are enough votes in Congress to override a presidential veto, or that many members actually want to be put in a position of having to vote against a clean air rule.

Sen. Alfonse D'Amato, R-N.Y.-who equated the long-range transport of pollutants from upwind areas into his state to "terrorism"-pledged to fight any attempts to delay or weaken the standards.

Another key Republican, Sen. John Chafee of Rhode Island, who previously had urged the EPA to abandon the tougher air standards, also said he would oppose efforts to reject the proposal. "I'm not anxious to deal with this legislatively," he said.

If Congress does not reject the proposal, opponents are expected to challenge it in court.

Clinton rejected the advice of some of his own economic advisors in adopting almost all of EPA Administrator Carol Browner's original proposal, although he allowed slightly more time for implementation. Browner had argued for months that the stricter standards were needed to protect public health, particularly for those who are most at risk from ozone and tiny airborne particles: asthmatics, elderly and young children.

"I think kids ought to be healthy," Clinton declared in a speech before a family forum in Nashville, Tenn., where he announced support for the plan.

"Work with us," he urged his critics. "We will find a way to do this in a way that grows the American economy."

Environmentalists cheered the first update to ozone standards in 20 years, and the first-ever restrictions on tiny particles.

"It's time to put the false claims about clean air behind us. On every major air pollution decision, the industry line is always the same," said David Hawkins, of the Natural Resources Defense Council, who headed the EPA's air program in the Carter administration. "They claim the harm from pollution hasn't been proven and that cleaning up dirty air is not affordable. Polluters are blowing smoke literally and rhetorically-the EPA's decision is vital to improving health and can be carried out at a reasonable cost."