AUGUSTA (AP) – Maine violated federal ozone standards only once during the summer, the state’s best showing in more than 20 years of record-keeping.

Martha Webster, the state’s air quality forecaster, said July 30 was the only day when violations occurred, when ozone-monitoring stations in Kennebunkport and Kittery exceeded federal standards. Last year, the state exceeded the standards on five days, she said.

In 2002, Maine violated the federal standard on 14 days. Violations occurred on 10 days in 2001 and three days in 2000.

Webster attributed the low number to favorable weather and less pollution from cars and other sources.

“Things are much better compared with the late 80s and early 90s. There’s no doubt about that,” Webster said. “The good news is, as more and more controls are put in place, when weather conditions are such that they bring in ozone and ozone precursors into the state, there will be less to bring in years to come.”

Ozone, a lung irritant, is formed as sunlight acts on pollutants in the air. It particularly affects those with respiratory illnesses, children, the elderly and anyone undergoing heavy physical exertion.

For several years, the state has maintained 15 sites to record ozone levels. Although measurements have been made at some places since 1980, other locations have changed over the years.

While efforts to reduce pollution from automobiles, industrial plants and other sources have reduced ozone levels, Webster said the biggest factor for ozone in Maine is the weather – in particular, the direction of prevailing winds.

When summer high-pressure areas form over the Atlantic Ocean near Bermuda, southwesterly winds tend to carry the pollutants that create ozone in Maine, Webster said. When the high-pressure areas form farther north, winds from the south are less likely to result in high ozone levels.

“Temperature plays a part, but it’s not the key element,” Webster said. “This year, (high pressure) was farther north, so when it formed we got winds more from the south.”

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