This report is specifically about Spokane, but it applies equally to Moscow-Pullman, Lewiston-Clarkston, and down to Boise. Via the Spokesman Review:
The air quality rating in Spokane deteriorated Monday morning to the “unhealthy” category, but improved some by afternoon.
Measurements from the Spokane Regional Clean Air Agency had shown air quality in category of unhealthy for all at times on Saturday, Sunday and Monday.
Monday afternoon provided some relief, as the air quality dropped to the “unhealthy for sensitive groups.”
…
Air quality in the “unhealthy” category is rare. Last year, daily air quality never reached that level. It happened five times, however, in August 2015, but not once in August 2016, 2014, 2013, 2012 and 2011.
The agency recommends that outdoor athletic events and practices be canceledwhen air quality reaches the “unhealthy” category.
The level of smoke in the air was measured at 153 on the air quality index on Monday morning at a monitoring station near Monroe Street and Wellesley Avenue.
The rating of unhealthy air for all persons starts at 150, but air quality from 100 to 149 is considered unhealthy for persons with medical issues.