Washington air quality today

A reader here is looking at two particulate scales at once. The Department of Ecology publishes the Washington Air Quality Advisory, which sets lower fine-particle thresholds than the federal AQI above the moderate band: at 50 micrograms per cubic meter of PM2.5 the federal index reads Unhealthy for Sensitive Groups while the state scale reads Unhealthy. Ecology attributes the difference to state toxicology work rather than to a disagreement about the measurement. The two never diverge by more than one category, and Ecology’s own advice when they disagree is to go by the worse of them. This site shows the federal AQI, because that is the number comparable across state lines.

Authority over winter wood smoke is split rather than held centrally. Ecology calls air-quality burn bans only in the eighteen counties that have no local clean air agency of their own — all of them east of the Cascades except San Juan — and elsewhere the local agencies and tribes call their own. A Stage 1 ban follows a prediction that the 24-hour PM2.5 average will reach 35 micrograms per cubic meter within 48 hours. A Stage 2 ban extends the restriction to certified wood and pellet stoves, with an exemption route for households that have no other adequate heat.

The Cascades split the state into two different problems: a wetter, more populated west, and a drier east where fire season does most of the damage. Because pages here follow metros, the rural eastern counties where Ecology itself is the burn-ban authority are the ones with the least written about them.