This week's blistering hot weather has done a number on Vermont's air.
Wednesday afternoon, the haze obscured the Adirondack peaks from the Lake Champlain skyline. It also elevated the state's ozone concentration, which can make it tough for some people to breathe.
The Department of Environmental Conservation's two air sampling shelters recorded "unusually high" ozone concentration Monday and Tuesday, said George Apgar, supervisor of the monitoring section of Air Pollution Control Division.
The Monday data for southern Vermont, measured at a site in Bennington, was found in the "unhealthy for sensitive groups" category. The Underhill site for northern Vermont hit the higher end of the "moderate" air quality category.
"When there's a lot of sunlight, we expect higher concentration," said Paul Wishinski, air quality planning chief of the state's Air Pollution Control Division. The combination of high temperature, sunlight and nitrogen oxide emissions from air conditioners, vehicles and power plants forms ozone, he said. Wind brought more emissions from New York City and Boston, he added.
Vermonters broke a summer record for power usage between 2 and 3 p.m. Tuesday, according to Central Vermont Public Service Corp.
"We believe the same condition is going to occur in the next days," Wishinski said. According to the National Weather Service, today will be partly sunny with a high in the low 90s.
The high ozone concentration is unusual, Wishinski said. Apgar said the Underhill data that exceeded the moderate standard last time was July 1999, and so was the Bennington sampling in June 2001.
"If the ozone concentration level we measure exceeds the standard, there's likely a chance people may be affected. They should be aware of what the situation is," Wishinski said.
Richard Valentinetti, director of Air Quality Division, said the symptoms of ozone exposure include coughing, nose or throat irritation and pain while taking a deep breath. Ozone can aggravate asthma, allergies and other lung diseases, and people can be more susceptible to respiratory infection, he said.
The Underhill sampling shelter is at the University of Vermont's Proctor Maple Research Center. A 768- cubic-foot, metal-skinned box draws air from the outside through a manifold into an ozone monitor. The Air Pollution Control Division staff download data every hour from the shelter's computer, Apgar said. Staffers forward the data to the city of Burlington and the federal Environmental Protection Agency, he said.
The air in New York City on Monday hit the higher end of "unhealthy" level, Apgar said. Last year Westford, Conn., ventured into "very unhealthy" territory, he said.
Last year, the Underhill sampling averaged a reading of "good" and has averaged "good" this year, he said.