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.

Full Story: http://www.boston.com/news/local/articles/2008/08/03/
a_gray_mark_on_area_smog/