A gray mark on area: smog

Population density limits progress, US officials say

As summer heat increases the odds of smog alerts, more stringent federal standards raise questions about the region's air quality.

According to the state Department of Environmental Protection, the Blue Hills air quality monitor in Milton has the third worst readings overall for ozone of the state's 15 monitors. High percentages of ground-level ozone (the main component of smog) caused by vehicle and power plant pollutants trigger regional unhealthy air alerts for sensitive groups such as people with breathing problems and children. All residents are warned to minimize outdoor physical activity on bad air days.

While the federal government says the region's air quality is getting better - as it is throughout the country - all of southern New England fails to reach clean air standards because of persistent smog problems, federal officials say.

"It's density," said Duxbury Selectman Andre Martecchini, an engineer. Heavy population concentration correlates with poorer air quality, he said.

Density can offset clean-air progress, such as tighter emission standards for vehicles and power plants. The US Environmental Protection Agency "has been saying since 1979 that air quality problems would be eliminated in five to 10 years," said Seth Kaplan, vice president of climate advocacy for the Conservation Law Foundation.

This year the EPA tightened its standard for ozone to 75 parts per billion, a more demanding level than the previous 85 parts per billion, based on studies of ozone's effect on human health. The change will mean more bad air days this year - 16 so far in the state, as of last week.

In addition to the Blue Hills air quality monitor, there are nearby monitors in Boston and Fairhaven.

So far this year the Blue Hills monitor registered ozone levels that exceeded the standard on four dates. The Fairhaven monitor, which gives air quality indications for south coastal communities such as Marion, Mattapoisset, and Wareham, also has registered four above-standard days.

Ozone is bad for human lungs, the EPA says. It can irritate the respiratory system, worsen asthma, inflame and damage the cells lining the lungs, aggravate chronic lung diseases such as emphysema and bronchitis, and reduce the pulmonary system's capacity to fight off bacterial infections. The effects are worse in children and exercising adults.

"You don't want to breathe ozone," Kaplan said. "When you breathe it in, it burns."

Ground-level ozone is produced when sunlight reacts with certain pollutants: nitrogen oxide, present whenever fossil fuels are burned, primarily by motor vehicles and power plants; and volatile organic compounds, byproducts of oil paints, insecticides, cleaners, industrial solvents, and chemical manufacturing.

Three of the four monitors with the worst readings for ozone in the state are located in western or central Massachusetts; the Blue Hills is "the third worst," state DEP spokesman Ed Colletta said.

Specialists say wind and weather patterns bring New York City-area pollution directly to the western part of the state, and that same pollution may also be affecting the Blue Hills readings because the monitor is at a higher elevation, Colletta said. What this means for air quality at lower elevations is unclear, because of a lack of monitors.

Given the role of sunlight, most bad air days occur in hot weather. The unhealthy air advisories issued by state and federal officials can prompt a vicious cycle, Kaplan said, since people respond to them by going indoors and turning up the air conditioner. The increased demand for electricity causes more power plants to fire up, producing more of the pollution that produced the warning to begin with, he said.

Global warming exacerbates the bad air problem by "having the heat on top of it," said Angela Vincent, director of the northeast region of ICLEI, an international association of local governments concerned about climate protection, whose members include Hingham, Hull, and Kingston.

The greenhouse gases causing the earth to warm are "part of the whole system" that contributes to bad air days, Vincent said.

Ann Brewster Weeks, litigation director for the Boston-based Clean Air Task Force, said the region's air quality is affected by pollution from New York, Connecticut, Pennsylvania, and the Ohio Valley. Her group fights for greater controls on emissions by coal-fired Midwestern power plants.

But "the outlook for relief may not be so good," Weeks said, pointing to the recent federal court decision which threw out the CARE system proposed by the Bush administration intended to cap power plant emissions.

While most of the region's air pollution may originate far away, "local traffic and pollution from cars and trucks and local power plants play a role," Kaplan said.

Two south coast coal-fired power plants in Somerset, Brayton Point and NRG, are faulted for high air pollution readings in Truro on the outer Cape. State-mandated controls have reduced emissions from these older plants, but they are a factor in the region's air quality, Colletta said.

The region's traffic congestion contributes. "All roads have an impact," said Martecchini, and congested roads have a greater impact. Advocates for a new lane on the congested Interstate 93 corridor have claimed that reducing congestion would improve air quality in communities along Route 128.

Weeks said the state needs more air quality monitors to give a clearer picture of the region's air quality. "The monitoring could be more robust," she said. "That's a concern." Some monitors operating in the '90s, including those in Easton and Scituate, were shut down because of funding cuts, Weeks said.

Colletta said a single monitor reading over the EPA standard may result in a bad air warning for all of Eastern Massachusetts because even if the air quality in one community isn't quite as bad as it is in the area that triggers the warning, it is probably close.

Colletta said: "It would be best to take precautions," by limiting strenuous activity during the hottest time of day.

Robert Knox can be contacted at rc.knox@gmail.com.