Despite a distinct lack of wind (average 1 mph, SW) PM2.5 levels have been steadily falling all day.

Readings are now below 30ug/m³, and although they are not dropping any further right now that's a big reduction from the red-lining 100ug/m³-plus levels we saw yesterday.
The concerning thing is that 30ug/m³ is still AQI 89 "Moderate" on the Air Now index. Readings of 35.5ug/m³ and above constitute an "Unhealthy" classification. So it seems like we are not out of the woods yet.