First the good news: Baltimore isn't so smoggy anymore.
The region's air pollution, once second-worst in the nation, has cleared up so much that levels of breath-robbing ozone in spring and summer no longer exceed the limit set by the Environmental Protection Agency.
Scientists and health experts welcome that news but say it is too early to declare victory in the region's long-running battle with smog. Even when ozone levels meet the federal limit, experts say, there is still a danger for many, including children, the elderly and those with asthma and other respiratory problems.
The EPA is considering lowering the ozone limit to protect more vulnerable people, something doctors and environmentalists support. And that probably would put Baltimore out of compliance again.
"The ozone standard is not sufficiently protective," said Dr. Gregory B. Diette, a pulmonologist at Johns Hopkins Hospital and associate professor of epidemiology at the Johns Hopkins Bloomberg School of Public Health. "People get sick and die at levels that are compatible with the current regulation."
The region's improvement in air quality, while real, was helped by the past two unusually cool summers. Ozone levels could easily rise, experts warn.
"Nobody is popping champagne corks just yet, because all it will take is another hot summer or two" and the area would not meet the federal ozone standard, said Russell Dickerson, an atmospheric chemist at the University of Maryland.
The EPA proposal to lower the limit is drawing fire from manufacturers, the coal and oil industries and others who contend that stricter rules on pollution would cause economic harm and cost thousands of jobs nationwide. A study done for the National Association of Manufacturers projects that a lower ozone limit could cost the economy $140 billion a year and put more than a million jobs at risk.
The air has gotten less smoggy nationwide over the past two decades. Cleaner-running cars and trucks and emissions controls on power plants played a big role in reducing the pollution that forms ozone, a colorless, odorless gas that irritates the lungs when inhaled.
The improvements have been pronounced in Maryland, which once rated second only to Los Angeles for having the nation's smoggiest air.
"We've seen downward trends pretty much since the early 2000s," said George S. "Tad" Aburn, air management director for the Maryland Department of the Environment.
He called it "great news" that the Baltimore area's air has finally met the EPA ozone standard. "It clearly shows we're making progress."
But Aburn acknowledged that clean-air efforts got a big assist the past two summers from "unusually kind" weather, which he does not expect to continue.
Last year was especially helpful, he said, with abnormally cool temperatures that kept ozone at low levels. It tends to form on hot, sunny, mostly windless days. The region also benefited from a shift in prevailing winds because there were fewer of the high-pressure systems that bring hot spells, Aburn said. That diverted smoggy air that usually blows into Maryland, often at levels above the federal health standard.
Still, Aburn said, federal and state laws and regulations, not weather, deserve most of the credit for the gradual improvement in air quality in Baltimore and across most of Maryland.
The Clean Air Act, passed by Congress in 1970 and amended in 1977 and 1990, required a series of smog-reducing measures, including cleaner-running cars, outboard motors and lawn mowers, cleaner-burning gasoline, and pollution controls on factories and many power plants. While many mandates were imposed nationwide, states also were required to take steps in communities that suffered the worst smog — such as requiring regular vehicle inspections to ensure that emissions controls are working.
"We can see tangible evidence that the Clean Air Act is working to improve people's health, and Baltimore is a case in point," said Frank O'Donnell, head of the group Clean Air Watch.
The state monitors pollution levels across Maryland, making hourly updates available online. It also publishes, in collaboration with local authorities in the Baltimore and Washington areas, a daily air-quality forecast, with color-coded predictions meant to advise the public.
According to state data, it has been three years since ozone reached "code red" levels in Maryland, when even healthy people are cautioned to limit their time outdoors. It has been five years since the level was that severe in the Baltimore area.
This year, there haven't even been any "code orange" days, when ozone levels are deemed unhealthy for children, older adults and anyone with a respiratory or heart condition. There have been just 15 days — all but one in May — when ozone reached "moderate" levels, meaning it is considered tolerable for all but "highly sensitive" individuals.
"People ought to feel good about that," said Diette, who specializes in studying how air pollution affects those with lung conditions. "They can't relax completely, though, when it's not a code red or orange day. There's still enough ozone to be harmful. It can still trigger an attack."
Janet Dubbert, one of his patients, has learned the hard way to be wary of pollution.
"The thicker the air, I automatically know it. It's a challenge to breathe," said the 62-year-old retired federal executive who has had a lung condition since 2007 that has left her less able to get out or exercise without becoming short of breath.
And even though summer smog is less severe, Dubbert said she hasn't really benefited, because her lungs have become "overly sensitive" to impurities in the air.
"Because ozone is a powerful oxidizing agent, it irritates and damages the airways, especially of people who have airways that are prone to constrict or tighten up," Diette said.
The EPA is legally required to periodically reassess whether its air pollution limits are tight enough to protect all Americans.
The EPA's current ozone standard of 75 parts per billion leaves many asthmatics and others with lung problems gasping for breath, Diette testified this week at a Senate hearing on lowering the standards. The Hopkins doctor said the agency ignored the advice of its scientific advisers in 2008 that the current standard is not protective enough, based on research showing health problems at lower levels. Further studies since then have made the case stronger, including evidence linking heart disease to chronic, relatively low-level ozone exposure.
Opponents of lowering the ozone limit say hundreds of counties considered in compliance would be forced to take new steps to make the air cleaner or face federal mandates. Many areas would have trouble meeting a stricter standard, they contend, because ozone is generated in a neighboring state or because of "background" ozone that occurs naturally.
The ozone that Marylanders breathe often comes from outside the state, Aburn said. But the state has joined with others in the Northeast to take concerted action to reduce smog-forming emissions. It has also petitioned the EPA to crack down on cross-border air pollution and challenged federal approval of air-quality plans in neighboring states, he noted.
The state's regulation of power plants also is an issue, because some coal-burning facilities that generate electricity only on the hottest summer days contribute to the region's ozone.
The Hogan administration blocked a rule adopted by its predecessor to require deep reductions in emissions of smog-forming nitrogen oxide after the owner of two Washington-area power plants warned that it would close the facilities and lay off hundreds of employees if required to comply. Instead, the Maryland Department of the Environment ordered the affected coal-burning power plants, including two in the Baltimore area, to maximize the efficiency of their existing pollution controls this summer while state regulators review what more might be required.
Only two Maryland counties — Cecil and Prince George's — are not meeting the EPA's ozone limit. The agency is considering lowering the limit by 5 to 10 parts per billion. While that might not seem like much, the number of Maryland counties deemed out of compliance would increase to nine or even 14, including Baltimore, according to the MDE.
Diette acknowledged that reducing pollution can be challenging, but he and other advocates for a lower ozone limit say the costs would be outweighed by the benefits, with fewer sick days taken from work and schools, and fewer emergency room visits and hospitalizations for asthma or other breathing difficulties.
"When my patients come to me and say what can I do about my asthma?" he said, "I tell them I can give them medications. I can't do anything for air pollution."