The official arrival of summer today is likely to feel pretty cool -- or at least an improvement over the sweltering, polluted final days of spring.
The Solstice occurs at 3:32 p.m. today, and forecasters said summer should arrive in Maryland on the heels of a cool front. Fresh air, with highs in the low- to mid-80s, was expected to drive out the 90-plus temperatures, oppressive humidity and smog of the past three days.
It was 96 degrees yesterday at Baltimore-Washington International Airport, breaking the record of 95, set in 1988.
Ozone, a component of smog, yesterday reached levels that triggered the third straight day of "code red" alerts from the Maryland Department of the Environment. Officials urged the elderly and people with respiratory problems to stay indoors as much as possible to avoid breathing the bad air.
"An ominous beginning to the summer season," said MDE spokesman George Krause.
Marylanders also were asked to limit driving, use public transportation whenever possible, avoid mowing lawns with gasoline-powered mowers and refuel their cars after dark.
Ground-level ozone is a lung irritant. It is created when chemical pollutants from automotive fuels and exhaust gases react in the presence of sunlight. As a consequence, its health risks are highest during hours of peak sunshine, and recede at dusk.
(Ground-level ozone, a pollutant, is often confused with Earth's protective, high-altitude "ozone layer." High-altitude ozone is produced naturally and shields the Earth from harmful ultraviolet solar radiation. Its seasonal erosion by man-made pollutants in recent decades has been recognized as a serious environmental problem.)
Last year, the Baltimore-Washington area exceeded federal standards for ground-level ozone on 11 days -- more often than any other metropolitan area on the East Coast. In 1993, standards were exceeded on 16 days.
Last month, state and regional authorities devised a pollution index for monitoring ozone and warning residents when levels get too high. Updated forecasts can be heard on the state's ozone hot line -- (410) 631-3247.
* An index of zero to 50 indicates "good" air quality -- code "green."
* An index of 51 to 88 causes a "code yellow" warning. Residents are asked to consolidate trips and errands, limit engine idling and reset thermostats to 78 degrees.
* A reading of 89 to 99 prompts a "code orange" warning. Residents are urged to refuel their cars after dark, avoid using gasoline mowers, and share rides.
* A "code red" occurs when the pollution index is forecast to exceed 100. Health advisories are issued.
At 4:30 p.m. yesterday, the ozone monitor at Fair Hill in Cecil County reached 111. Another at Fort Meade reported 107. The index at Lake Clifton in Baltimore was 99.
"Jogging is terrible in pollution alerts," said Dr. Peyton A. Eggleston, a pediatric asthma specialist at Johns Hopkins Hospital. Even healthy people will experience respiratory, eye and nose irritation as the ozone and sulfur dioxide inflame delicate tissues.
"But people with lung diseases will actually have an abrupt worsening" of their symptoms, he said. Among the most at-risk are asthmatics, people with chronic bronchitis or cystic fibrosis, infants who had respiratory distress as newborns, and the elderly.
The tissue damage is mostly reversible, but "long-term, heavy-duty exposure causes more permanent changes in the lungs," Dr. Eggleston said.
Despite yesterday's code red warnings, activities for 75 asthmatic children continued as planned at Camp Superkids in Laytonsville, in Montgomery County. The camp is sponsored by the American Lung Association of Maryland and Johns Hopkins Bayview Medical Center.
"They were very aware of the code red," said association spokeswoman Susie Breaux. "Fortunately, the kids do most of their outdoor and strenuous activities -- nature hikes and karate -- in the morning when ozone levels are lower."
Also, "We have medical professionals who carry around all the kids' charts and medications, so if they need an inhaler, they'll have it immediately, where they are," Ms. Breaux said. Camp cabins are air-conditioned.
The lung association sponsors similar camps around the state throughout the summer. For information call (800) LUNG USA.
Although the forecast called for some relief today, Jim Wagner, a senior forecaster with the National Weather Service Climate Analysis Center in Camp Springs, said it won't last.
"The pattern is beginning to change, and it looks like we might see more heat coming in by the weekend or early next week," he said.
Looking ahead to July, August and September, he said a slightly increased chance of above-normal temperatures exists in middle Atlantic and southeastern states.
But the computer models could provide no clear guidance on whether rainfall would exceed or fall short of normal amounts.
As hot as it was here, Mr. Wagner said, "We never did get the really hot air. . . . Just about every city in New England had temperatures in the 90s, even the coast of Maine. And Burlington, Vt., hit 100."