Wildfires play part in local haze

By John Dodge | The Olympian • Published July 02, 2008

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Smoke from Northern California fires has combined with regionally generated air pollution and weather conditions to give South Sound a hazy look, air-quality officials said Tuesday.

Measuring air quality

The Air Quality Index is a combined measurement of five air pollutants regulated by the federal Clean Air Act: ground-level ozone, particle pollution, carbon monoxide, sulfur dioxide and nitrogen dioxide.

The higher the number, the greater the public health concern.

0-50: Air quality poses little or no health risk.

51-100: Air quality is acceptable, but pollution could be a moderate health concern for a small number of people.

101-150: Sensitive groups such as people with lung or heart disease could experience health problems.

151-200: Everyone is vulnerable to ill effects, such as breathing problems.

201-300: Pollution this high would trigger a widespread health alert.

301 or more: Emergency health conditions exist.

"Fine particulates from the California wildfires are moving into the region," the Puget Sound Clean Air Agency reported.

The Seattle-based agency said the fires are contributing to a moderate air-quality condition in central Puget Sound. In South Sound, air-quality readings Tuesday taken at a monitoring station in Lacey registered 33, which is in the "good" range, said Richard Stedman, executive director of the Olympic Regional Clean Air Agency.

Much of the air pollution carried north from the fires is staying in the upper atmosphere, creating hazy skies but not necessarily showing up at the ground-level air-quality-monitoring stations.

"We get a lot of mixing of air in the lower-level atmosphere," said Greg Sinnett, a state Department of Natural Resources meteorologist.

He said much of the hazy look is the result of air pollution from motor vehicles and industry cooking in the heat and creating smog, or ozone. "We could be getting some residual smoke from the Northern California fires," Sinnett said.

"But generally speaking, we're our own worst enemy when it comes to air pollution."

A large upper-level low-pressure system above Northern California has created a flow of air from south to north that could be carrying wildfire smoke to Washington, said Dennis D'Amico, a National Weather Service meteorologist based in Seattle.

The Puget Sound Clean Air Agency predicted that air quality will improve early next week when a weak onshore flow of air over the region strengthens.

John Dodge covers the environment and energy for The Olympian. He can be reached at 360-754-5444 or jdodge@theolympian.com.