Spokane choked with hazardous air quality for fourth straight day

For the fourth straight day, air quality in Spokane was measured as hazardous Thursday as smoke from regional wildfires continues to keep the Inland Northwest in a haze.

Five air monitors that measure particulate matter in Spokane County measured air as “hazardous” at 3 a.m., according to the Department of Ecology. That’s the worst reading in the six-category air quality scale.

Heavy smoke began blanketing much of the Northwest on Monday. It isn’t expected to lift until Friday. On Tuesday, Spokane had the worst daily air quality reading since records began in 1999.

Air quality monitors in North Idaho mostly showed slightly better readings. Rathdrum and Sandpoint had “very unhealthy” air at 4 a.m. Kellogg, St. Maries, Moscow, Plummer and Bonners Ferry had “unhealthy” air. “Hazardous” air was measured at Lapwai and Juliaetta.

The Spokane Regional Clean Air Agency listed air quality at the five Spokane County monitors as “very unhealthy” most of Thursday. The agency and the Department of Ecology use a different calculation using the same data to determine current air quality.

Air pollution agencies use a 1-500 scale to measure particulate matter. Numbers 300 or higher are considered “hazardous.” Numbers 200 or more are considered “very unhealthy.”

On Tuesday, air pollution averaged 254 during during the day, the highest measurement on record and the first time since 1999 that a daily reading was in the “very unhealthy” category. That’s the same year records began to be compiled by the Spokane Regional Clean Air Agency.

Wednesday’s number was only slightly better at 245, said Stephanie May, the air agency’s spokeswoman. That’s now the second-highest daily reading on record.

A cold front is expected to start moving the smoke out of the Spokane area starting late Friday morning, said National Weather Service meteorologist Jeffrey Cote.

Southwest winds of 5 to 10 mph are expected, with gusts as high as 20 mph in the afternoon. It likely will be breezier on Saturday, Cote said.

As of the end of the day Wednesdsay, Spokane had gone 70 days without measurable rain. Without rain, Spokane will break the record of 73 days at the end of Saturday.

Cote said there’s a 20 percent chance of rain on Friday morning.