The unusually hot, dry weather this summer helped to produce unhealthy levels of air pollution on 17 days this year in Maryland - a major increase over the past two years, atmospheric scientists and environmental officials said yesterday.
Environmentalists are blaming this year's spike in "code red" ozone readings - up from 10 last year and four in 2000 - on increasing pollution by utilities and other industries. They also warn that the Bush administration is moving to relax federal Clean Air laws.
"Things are just getting worse," said Colleen Heller, an environmental associate with MaryPIRG, the Maryland affiliate of the nonprofit U.S. Public Interest Research Group Education Fund. "The public needs to know about this. We're paying the price for their pollution."
But atmospheric scientists say the long-term pollution trends have been downward, though much remains to be done. They blamed the more recent ozone problems on unusually hot, dry, sunny weather the past two years.
"It was a brutal summer for air quality," said Russell R. Dickerson, professor and chairman of the meteorology department at the University of Maryland, College Park. "We had been making progress, and this just blew us out of the water."
Ozone is an invisible, odorless gas, a form of oxygen created when industrial and automotive air pollutants react in the presence of sunlight. In high concentrations, ground-level ozone can cause coughing, shortness of breath, headaches and eye and throat irritation. It is especially dangerous for people with lung ailments, children and the elderly.
Data compiled by PIRG showed that ozone monitors last year recorded more than 4,600 instances of unhealthful ground-level ozone in 42 states and the District of Columbia - up 10 percent from the previous year.
Maryland ranked fifth in the country, after California, Pennsylvania, Texas and Ohio, with 214 violations of the federal ozone health standard, up from 103 the year before.
This year, based on preliminary data from 20 states and the District of Columbia, ozone violations nearly doubled compared with 2000, and increased 23 percent over last year.
PIRG is using the ozone violation numbers to bolster its arguments for more aggressive enforcement of the Clean Air Act. The group also wants Congress to reject efforts by the Bush administration and industries to relax so-called "New Source Review" rules governing emissions by the nation's older factories and power plants.
The Bush administration, and industry advocates such as the National Association of Manufacturers, argue that the rules are too complicated, and only make it difficult for utilities to comply. President Bush has proposed a "Clear Skies" initiative that would set new pollution "caps" and give industries more flexibility and time to comply.
Robert Maddox, spokesman for the Maryland Department of the Environment, said the number of days when ozone in the state exceeded the federal health standard of 125 parts per billion over a one-hour period has increased in each of the past three years.
But "a lot of this was weather-based," he said. "We had a long drought and very little rainfall during the summer months, and ozone forms as a reaction to heat and intense sunlight."
The number of days with highs of 90 degrees or more at Baltimore-Washington International Airport climbed from seven in 2000 to 20 last year and 44 this year. There were fewer ozone violations in 2000 because it was a wet, cool and cloudy summer in much of the state, Maddox noted.
"We're making improvements in some areas," the state spokesman said, "but that's being offset by the fact there have been large increases in the number of vehicles on the road."
Dickerson, the UM meteorologist who has studied ozone formation, said emissions of key ozone-forming chemicals such as sulfur compounds and hydrocarbons have gone down steadily since the 1970s.
Nitrogen oxides - another key smog ingredient produced by vehicles and power plants - are harder and more costly to control, he said, and "have only begun to come down very recently ... and that's the main reason we haven't made very dramatic progress."
On one point, though, he agreed with the environmentalists: "In principle, if those large, old power plants are allowed to continue to operate with essentially no pollution control, we are never going to be in compliance with the Clean Air Act."