Activists believe that publicly documenting the scope of the pollution would increase pressure to reduce it, either through government regulation or voluntary action.
Michele Merkel, Chesapeake coordinator of the Waterkeeper Alliance, said people who live near chicken houses have complained to her group of noxious odors and breathing problems.
Though the EPA has not set any air-quality standards for ammonia from farms, studies indicate that levels of the gas in the exhaust vents from barns can be higher than the workplace exposure limits set by the U.S. Occupational Safety and Health Administration, according to Eric Schaeffer, a former EPA official who heads the nonprofit Environmental Integrity Project.
Schaeffer said responsibility for filing the reports ought to fall on the poultry companies for which farmers raise chickens under contract.
"The reports themselves are pretty simple," he said. "Companies like Perdue and Allen Foods, they should be doing these."
The EPA launched a study of air pollution from poultry farms last year. Ryan said results would not be available until sometime next year.
But other studies indicate farms are a major source of the gas, experts say.
"Agricultural emissions in general are the dominant source of ammonia," said Joseph R. Scudlark, a lab director at the University of Delaware who has studied ammonia emissions from poultry farms on the Delmarva Peninsula.
Ammonia releases contribute to the bay's woes because they add to the estuary's overdose of nutrients. Nitrogen and another fertilizing nutrient, phosphorus, spur vast growths of algae in the bay. As those floating microscopic plants die, sink and decompose on the bottom, they deplete the water of the oxygen that fish need to live.
As much as a third of the nitrogen fouling the water comes from the air, according to Lewis Linker of the EPA's Chesapeake Bay Program. While most of the nitrogen in air comes from coal-burning power plants or vehicle exhaust, about a third is from farms.
But in agricultural areas such as the Eastern Shore, ammonia from farms makes up the majority of nitrogen coming from the air, said Linker. Nitrogen emissions from vehicles and power plants have declined in recent years as air pollution rules have tightened. Farm emissions, which are not regulated, have not changed.
"If we are serious about getting a handle on nitrogen loads to the bay, we need to be concerned about this potentially significant source of nitrogen emissions," said Merkel.
"We're being blamed for everything on the bay, and we don't accept that," responded Lobb of the chicken council.
The Sierra Club's Hopkins said environmental groups met with federal budget officials in November and urged them not to allow the exemption.
"But every indication we've had is they are headed in that direction," he said. "We certainly hope they will reconsider."
