Federal and state standards for measuring air quality rely on the same methodology, but they have different meanings. An app that equates air quality with smoking cigarettes may not be reliable.

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If you’ve been confused trying to figure out exactly how unhealthy the smoky haze that’s settled over Seattle is, you are not alone.

Over the past two weeks, reports of how bad the air has been were inconsistent even on the same day. One website, for example, might list air quality as being “unhealthy for sensitive groups” while another classifies it as “moderate.” Is Seattle air really as bad as smoking several cigarettes?

While most air quality gauges use the same national data, each may interpret the information differently, according to the Washington state Department of Ecology. The state has been hit hard for the second year in a row by smoke from wildfires raging in its forests and surrounding regions, raising concerns about the adverse impact on the health of its residents. Some parts of Puget Sound experienced ash falling from the sky on Tuesday, an almost unprecedented occurrence.

Department of Ecology spokesman Andy Wineke explained that some websites, such as AirNow.gov and the main page of the Washington Smoke Information blog, use national standards for determining air quality. Those classifications are: “good,” “moderate,” “unhealthy for sensitive groups,” “unhealthy for everyone,” “very unhealthy for everyone” or “hazardous for everyone.”

Websites that are specific to Washington state, however, ascribe to the Evergreen State’s stricter standards, he said. Therefore, assessments found on the Washington State Air Monitoring Network may sometimes list an area as being “unhealthy for sensitive groups” on the same day a federal website deems it “moderate” or even “good.”

“Ours are generally one level above what is listed on the (national) smoke blogs,” Wineke said. “We know it’s confusing, but our standards are more protective and we think that’s the right tack to take on Washington pollution.”

Another measure of air quality is offered by a cellphone application that equated breathing Seattle air on Tuesday to smoking eight cigarettes.

The app takes real-time data of atmospheric particulate matter, and converts it into the equivalent of particulate matter that would be consumed from smoking cigarettes. Other pollutants are in the air, including sulphur dioxide, formed by fossil fuel combustion, carbon monoxide and nitrogen dioxide, formed by emissions from motor vehicles, gas heaters and cigarette smoke, and ground-level ozone, formed by smog.

Wineke said that, based on conversations with a toxicologist in his department, the comparison is a stretch.

“Cigarette smoke and wildfire (smoke) are very different kinds of exposures,” he said.

While cigarettes contain chemicals not found in wildfire smoke, the latter is still harmful.

“The lungs will be blacker than they would have been had the particulate matter not gotten in there,” Wineke said. The biggest concern is the microscopic particulate matter produced from wood getting into the lungs. Because it’s so small, it’s able to pass into the bloodstream, he said.

As for state versus federal air-quality standards, Wineke said both interpretations are accurate. His department uses the national air quality index numbers on its smoke blog because the U.S. Forest Service, and other federal agencies contribute to the blog. Washington’s more stringent standards are used by his department and others when it comes to issuing health advisories for residents.

Stations around the Puget Sound were reporting “unhealthy” air quality for the third straight day on Tuesday, according to airnow.gov. In response, some cities and school districts limited or canceled outdoor activities to reduce exposure to the air.

In Seattle, two outdoor pools and four wading pools were closed Tuesday and Wednesday and Bellevue closed its swimming beaches on Tuesday. Some schools moved football practice indoors.

Improvement is expected to begin Thursday, when Pacific Ocean marine air starts coming in, according to the National Weather Service’s forecast.

By the weekend, the smoke should give way to a much more familiar — and perhaps now more welcome — feature of Northwest weather: rain.