Lori Taylor always feels a pang of worry on hot, sticky summer days as she watches her 10-year-old daughter, Latasha, riding her bike or jumping rope with friends outside. Taylor wants Latasha to play and keep up with her pals, but she wonders about her daughter's asthma: Could she overdo it and trigger an attack?

At Camp Happy Lungs, sponsored by the American Lung Association, Latasha and nearly 50 other District children ages 7 to 11 spent a week in late July at a Patuxent River campground in Upper Marlboro, learning to strike a balance between being active and avoiding breathing problems. Many had a history of asthma episodes triggered by exercise outdoors. They learned how to play without prompting an attack, take their medications properly, spot signs of trouble and take precautionary breaks.

Air pollution and asthma attacks often go hand in hand, and doctors warn that children throughout the Washington area have ample reason to be cautious. The region is one of roughly a dozen urban areas in the country with levels of ozone -- a component of smog -- sufficient to exacerbate breathing troubles in children, the elderly and people with lung disease.

How carefully factories and power plants need to control the air pollution that contributes to forming ozone in urban areas is a matter of dispute. This summer, Earthjustice, the legal arm of the Sierra Club, sued the U.S. Environmental Protection Agency to overturn its decision to allow states and the District to relax some current smog pollution control requirements while state governments and industry representatives craft plans to meet new, more comprehensive pollution control standards.

The environmental advocacy group said the EPA's decision to let states waive some stricter smog controls puts residents in areas such as Washington, Houston, Dallas, Philadelphia, Chicago, New York City, Boston, Sacramento, Milwaukee and Baton Rouge, La., in danger of increased industrial air pollution. Because urban areas don't have to fully comply with the stricter standards for several more years, the EPA's decision could expose cities to worse air quality in the interim, Earthjustice said.

Maryland, Virginia and the District are required to adopt new plans for further restricting emissions by 2007 but won't have to bring air pollution levels down to the lower limits until 2010.

"This is like saying we need to have a stricter speed limit, but for now everyone can go faster," said David Baron, a lead attorney on the case at Earthjustice. "It makes no sense to allow pollution to increase when you're saying you need stronger protection."

The extent to which the EPA's decision will directly affect emissions and air quality in the Washington metropolitan area is unclear. But the policy change has prompted some concern -- and a local and national debate -- about whether waiving current pollution restrictions is wise for urban areas that have long been struggling to meet air quality standards.

Environmentalists are particularly concerned that the EPA is letting states temporarily waive air pollution controls for new and expanded plants even though limiting or offsetting any increased industrial emissions would necessarily be part of meeting the future standards.

EPA spokespeople and policy officials said the period between two pollution standards is always a challenge. They said it is not fair to force governments and industries to continue to adhere to one set of pollution limits while a new set is being crafted.

"For a smooth transition to the more protective ozone standards, it is essential that state and local governments work to meet one standard without losing progress," EPA spokeswoman Eryn Witcher said. "Asking states to meet two standards at once defies common sense and risks confusion and backsliding."

Power plant officials said it is highly unlikely that the relaxed standards will lead to increased industrial pollution in most urban areas, including Washington. They said that is because plants and factories that emit pollutants that form smog face even stricter rules in the Northeast, under a special compact aimed at combating high ozone levels.

The ozone pollution that is hazardous to people with asthma and vulnerable lungs is often confused with a good kind of ozone, which occurs naturally in the stratosphere and forms a layer that protects the Earth's surface from ultraviolet light.

The "bad ozone" is found much closer to the Earth's surface and is the result of air pollution from automobile engines and power plants. Vehicle exhaust and industrial emissions release nitrogen oxide gases and volatile organic compounds, byproducts of burning gasoline and coal. Nitrogen oxide gases and volatile organic compounds chemically combine with oxygen to form ozone during sunny, hot days in late spring, summer and early fall. High levels of ozone are usually formed in the heat of the afternoon and early evening, dissipating during the cooler nights, according to the EPA's Web site.

The EPA regulates ozone under the Clean Air Act. Fixed monitors around the metropolitan area measure average concentrations of pollution over eight-hour blocks. The EPA takes the fourth-highest measurement each year over three years to determine whether the ozone standard has been violated.

The EPA classifies air conditions in urban areas as severe, serious or moderate, depending on their ozone levels. The Washington region has long been classified as having severe ozone levels. Under the temporarily relaxed standards, the EPA decided last year to reclassify several severe urban areas, including Washington, as moderate.

With that change, a host of industrial plants avoided limits on emissions. In communities classified as having severe ozone levels, EPA rules require that all plants that have the potential to emit 25 or more tons per year of pollution must curtail or offset new emissions. Plants in communities with moderate ozone levels must curtail or offset new emissions only if they emit 100 or more tons of pollution annually.

The interim changes by the EPA are expected to put metropolitan areas such as Houston and Philadelphia at risk for increased industrial pollution because they have numerous plants and factories.

Some environmentalists said they fear that a new power plant could begin operating in Virginia or Maryland, adding to the region's overall pollution problem. In addition, Washington area plants that are smaller polluters could be allowed to generate more emissions under the relaxed restrictions.

Jim Potts, Pepco Holding Co.'s vice president for safety and the environment, said a stricter regional pollution control pact that governs industry in the Northeast, under the Ozone Transport Commission, should protect against industrial plants increasing their emissions.

"While states in theory could relax the standard, it would be silly to do that because they know they can't meet the [new] standard now," Potts said.

The biggest concern for Washington and several other Northeast cities is automobile emissions, he said.

"Increasingly, the Ozone Transport Commission is focused on ways to control mobile sources," Potts said.

Many environmental advocates think curtailing any pollution that contributes to ozone is essential to improving the quality of life in the city and the nation.

The Air Quality Index for reporting pollution levels ranges from good to very unhealthful and includes color-coded rankings. From June through early August, the Washington area had 14 Code Orange days, which means breathing the air outside was unhealthful for vulnerable individuals, including the elderly, people with lung problems and children who are active outdoors.

This year the region has had no Code Red days, in which the air outside is deemed unhealthful for everyone and neither children nor adults should spend considerable time active outdoors. The area had two Code Red days in early July 2004.

Rolando Andrewn, executive director of the D.C. chapter of the American Lung Association, said that given the well-known problems with Washington's air quality, he is surprised the EPA would be willing to relax limits on car or industry emissions while pushing to implement stronger standards.

"Some kids may be sicker and some adults may even perish because of worsening air pollution," said Andrewn, whose group sponsors Camp Happy Lungs for D.C. kids with asthma.

Eric Gilliland, executive director of the Washington Area Bicyclist Association, said local cyclists also favor pollution controls: On a bad ozone day, their lungs can burn after a long ride.

"This time of year, when the weather is so hot and muggy, the pollution just tends to hang over the city," Gilliland said, noting that many D.C. cycling shops sell filter masks for cyclists worried about pollution. "The rules should be held to, and any relaxation . . . is only going to cause more damage to people's health."

Lori Taylor, who helps run Camp Happy Lungs, said her challenge as a parent is trying to protect Latasha against an asthma attack while making sure her daughter doesn't see her condition as a disability.

"I don't want her to feel like every time she steps outside she has to limit herself because of the air pollution," Taylor said. "I've said, 'It's okay to take breaks.' I can just look at her red face and say, 'Latasha, it's time to slow down.' "

Taylor said she can't imagine why the government would allow a temporary increase in pollution emissions.

"If regulations become less strict, the air pollution problem will worsen," she said. "That means there will be more Code Red and Code Orange days, which is going to put a lot more children at risk. . . . Why would we want that?"

Sierra Club attorney David Baron says, "It makes no sense to allow pollution to increase when you're saying you need stronger protection."