CONCORD, N.H. – Even the mountains and beaches of northern New England offered no escape as a heat wave combined with unusual wind patterns to produce a hot milky haze that descended on the region for the fourth straight day Wednesday.

“The air is thick,” said Scott Hamilton, who ran about three miles at noon Wednesday in Concord, despite official warnings about exercising in the dirty air.

“I found it a little laborious to breathe,” said Hamilton, 51, who carried a water bottle in his hand as he ran.

The National Weather Service also said the temperature hit a record 99 at 2:14 p.m. in Concord, where official records are kept. The record was 98 for an Aug. 14, set in 1947.

The hot and humid weather is expected to last through Friday.

Maine officials warned that some of the worst ozone levels in the state were along the popular southern coast and at Acadia National Park.

The Maine Department of Environmental Protection issued an advisory for unhealthful ozone levels for the fourth straight day for parts of the state.

Atop New Hampshire’s Mount Washington, the highest point in the Northeast, meteorologist Katie Hess said visibility was only about nine miles.

“We can hardly see the clouds through the haze,” she said.

Earlier this week summit temperatures set new daily records – 69 degrees Monday and 67 Tuesday. On Wednesday the high of 68 fell three degrees short of the record for the date.

New Hampshire officials warned that ozone levels at elevations above 3,000 feet were unhealthful for children, the elderly and people with respiratory diseases.

Ozone acts differently at high elevations, said Georgia Murray, an air quality staff scientist for the Appalachian Mountain Club.

“Down in the valleys [the ozone] declines overnight when the temperatures drop. At the higher elevations it doesn’t, so it just builds and builds as long as these conditions continue,” she said.

The government considers ground level ozone unhealthful when it exceeds 85 parts per billion. The level on the summit was in the high 80s this week, Murray said.

Wednesday’s highest reading at the state’s 14 monitoring points was 137 parts per billion at Rye Harbor, Black said.

The state’s last ozone readings above 100 were in June 2001.

Black and others blamed unusual wind patterns bringing in more out-of-state pollution than usual, and the heat, which “cooks” pollutants into smog.

Black said cars are a major source of both ozone and particulates.

Wednesday was the third consecutive day the state encouraged people to take precautions such as limiting outdoor exercise because of the dirty air.