The EPA has targeted 22 states - including all of those in the Chesapeake "airshed" - for new air pollution controls as part of an effort to reduce smog-causing chemicals that travel across state boundaries and to meet new air quality standards.

The action, expected for months, requires nitrogen oxide emission reductions from most of the eastern half of the country from Massachusetts to Missouri and as far south as Georgia.

The states must develop plans within two years outlining how they will achieve the specific reductions set by the EPA. The cuts must be implemented by 2002 with air quality improvement taking place by 2005.

EPA Administrator Carol Browner said the new requirements are key to reducing regional pollution problems and for meeting tougher and controversial air quality standards for smog-causing ozone approved last summer.

"Smog annually causes hundreds of thousands of cases of lung disease in the United States," Browner said. "These reductions alone will help almost all areas to achieve EPA's new, more protective air standards in a cost-effective, common sense way."

Areas that do not attain the EPA's new air standards after fully implementing the prescribed nitrogen oxide reductions will have additional time to take further action. All areas must attain the new ozone standard by 2012.

The EPA's action has the potential to help the Bay because airborne deposition contributes about a quarter of all the nitrogen that enters the Chesapeake. Excess amounts of nitrogen spur algae blooms that block sunlight to important underwater plants which provide food and habitat for waterfowl, blue crabs, juvenile fish and other species. When the algae die, they sink to the bottom and decompose in a process that depletes the water of oxygen needed by other species.

Most of the nitrogen that falls on the Bay and its 64,000-square-mile watershed results from nitrogen oxide emissions stemming from fossil fuel combustion in power plants, automobiles, boats, construction equipment and other sources.

Nitrogen oxides can travel hundreds of miles after leaving a smokestack or tailpipe. As a result, computer models have estimated that much of the nitrogen oxide emissions affecting the Bay originate from outside the watershed, but within a 350,000-square-mile "airshed" - an area 5.5 times larger than the Chesapeake watershed.

The EPA's proposed action requires significant reductions from many states within that airshed, especially those directly upwind in the Ohio Valley. Nitrogen oxide emissions from those states have been blamed for being a major contributor to chronic summertime smog problems in many East Coast cities.

In fact, many Northeast states say the EPA is not taking action fast enough. Pennsylvania, New York and several New England states filed papers in October announcing their plans to file suit against the EPA to force faster action.

While the EPA is leaving it up to the states to determine how to make the emission reductions, the Northeastern states - which have long blamed Midwestern power plants for fouling their air - want the agency to immediately order emission reductions from those facilities.

James Seif, secretary of the Pennsylvania Department of Environmental Protection, called the EPA's plan "a good first step" but said he wants the EPA to set specific emission limitations and reductions for coal-fired power plants in 19 southern and Midwestern states.

"We need the EPA to act and act quickly to address the issue of dirty air blowing into Pennsylvania," Seif said. "Pennsylvania alone cannot solve its air quality problems - we need every state to do its share, in a timely fashion."

Seif said work done by the 37-state Ozone Transport Assessment Group provided the information needed by the EPA to take such action. OTAG, which represented all the states east of the Rocky Mountains, spent two years studying how the long-range transport of pollutants, mainly nitrogen oxides, affect air quality in downwind areas. The group released its report earlier this year.

The EPA based its nitrogen oxide reduction targets on OTAG's work, but chose to leave it up to individual states to determine where to look to make the cuts. But the EPA said reductions in nitrogen oxide emissions from power plants were less costly than reductions from other sources, costing as little as $1,700 per ton versus $3,100 per ton from cars.

To ensure that the reductions are as cost-effective as possible, the EPA is also developing a market-based emissions trading system under which utilities that cannot meet the reductions can buy and trade "credits" from utilities that exceed reduction limits.

Although electric utilities are required to make some cuts in nitrogen oxide under an acid-rain control program, the new EPA requirements will force them to make even deeper reductions.

States will have one year to review, and possibly challenge, the EPA requirements. They then would have another year to show how they plan to achieve the required reductions over an additional five-year period.

Failure to develop a state implementation plan could force the EPA to impose a federal plan. If states do not meet the pollution reductions in a timely manner, the federal government also could withhold federal highway funds.

Reductions being sought, state by state

These are the percent reductions in nitrogen oxide emissions that the EPA is seeking from various states. Generally, emission reductions from Northeast and Mid-Atlantic states are less than those being sought from Midwestern states because the former have already taken some steps to reduce emissions.

Alabama - 36

Connecticut - 21

Delaware* - 28

Georgia - 35

Illinois - 38

Indiana** - 42

Kentucky** - 40

Maryland* - 36

Massachusetts - 32

Michigan** - 32

Missouri - 43

New Jersey** - 25

New York** - 19

North Carolina** - 34

Ohio* - 43

Pennsylvania* - 32

Rhode Island - 19

South Carolina** - 31

Tennessee** - 35

Virginia* - 21

West Virginia* - 44

Wisconsin - 35

* States that are entirely within the Chesapeake Bay airshed
** States that are partially within the Chesapeake Bay airshed