Harford County is among the nation's most polluted counties in terms of ozone levels, according to the latest figures from the Environmental Protection Agency. Likewise, Maryland is one of 31 states failing to meet EPA health standards for ground-level ozone.
But it is not all bad news.
"There has been a dramatic reduction in the amount of what we used to produce," said Randy Mosier, an air quality planner for the Maryland Department of the Environment.
In the 1980s, the state averaged 20 days or more of ozone readings above national air quality standards. In the '90s, the average decreased by 50 percent. Today, Maryland hovers around 10 code red days a year, Mosier said.
To the detriment of Harford, the amount of ground-level ozone often depends on a combination of geography and the way the wind blows. Weather conditions account for most "ozone action days," the high ozone-level days that occur on 90-degree and above days.
About 60 percent of pollution is imported downwind from neighboring industrial states, based on research from MDE and the University of Maryland. Ohio River Valley power plants, for example, are common culprits releasing high levels of ozone.
"Even though there are things beyond our control, there are still things we can all do to help," said Susan Kelly, director of the Harford County Health Department's Bureau of Environmental Health.
By limiting daily activities, Kelly said, residents can make a difference. She recommends refueling cars after dusk; limiting driving; putting off painting until later; and avoiding mowing lawns with gasoline-powered mowers.
If 20 percent of the people in the state took these measures, it would "shave off" some of the worst ozone days, added Mosier.
Harford County government has had an administrative policy in effect since 1996 to help reduce ozone on high-level days. The Department of Public Works, for example, is restricted to refueling vehicles later in the day and to minimizing the spraying of herbicides and pesticides. Other measures are being considered.
Educating the public is a high priority for decreasing the ground-level ozone and for preventing health problems.
Breathing ground-level ozone can trigger a variety of ailments, including chest pain, coughing, throat irritation and congestion, according to the EPA. It is particularly harmful for those with respiratory disease because ground-level ozone can reduce lung function and inflame the linings of the lungs.
During summer months, spending time outside where ozone health standards are exceeded puts people at risk, health officials warn. Also at risk are crops, trees and other foliage. The EPA estimates ground-level ozone is responsible for about $500 million a year in reduced crop production.
Beginning June 15, all areas will be designated by the EPA as being in attainment or nonattainment and classified based on the severity of ozone conditions. Once the designations and classifications are in place, communities will be required to prepare a plan to reduce ground-level ozone.
Harford ranks No. 15 and Cecil County No. 24 out of the 474 counties nationwide deemed to be in nonattainment. The country's remaining 2,668 counties meet the new standards.
EPA's new eight-hour ozone standard will replace the one-hour standard that has been in place since 1979. The eight-hour standard was issued in 1997 after research showed that longer-term exposure to lower levels of ozone can also affect human health, according to the EPA.
Deadlines for states to adopt the eight-hour standard range from 2007 to 2012, depending on the severity of an area's ozone problem. Maryland has until 2010.
The EPA has a six-color scale, with codes red, purple and maroon representing the most severe. Maryland's ground-level ozone levels have not reached code maroon, according to officials.
To better inform the public, however, the MDE will be adding code purple warnings to its daily alerts that are disseminated to the media, government agencies, businesses and others.
The new eight-hour average also can better pinpoint code purple conditions, which are more severe than code red. "It's a stricter standard that is a measurement of going beyond [traditional] air-quality standards," said Mosier.
A network of 16 or 17 monitors from Western Maryland to the tip of the Eastern Shore is in a state of constant flux, according to Mosier.
"We are always adding some to the system, or combining some, or moving them for one reason or another," he said.
The two air quality monitors in Harford, at Edgewood and Aldino, typically measure some of the state's higher readings, said Mosier.
In response, government, environmental groups and businesses have initiated an Ozone Action Days program to help prevent air pollution when high ozone levels are predicted and to assist in alerting the public.