2019 vs. 2020 PM2.5 Concentrations at Two Stations in California

I updated and extended my look at California air pollution (PM2.5 - particulate matter below 2.5 microns in size, generally deriving from combustion) in the wake of the coronavirus crisis, at two stations in California: Long Beach (near Highway 710) and Downtown Sacramento T Street. Series 1 (orange) is 2019 data; Series 2 (blue) is 2020 data.

Based on February data, at both stations, 2020 was shaping up to be considerably dirtier than 2019. In Sacramento, the dirtier air was probably occurring because there were fewer storms blowing through.

Then the coronavirus crisis struck.

In Sacramento, the reduction is enough to make 2020 particulate concentrations equivalent to 2019 levels. In Long Beach, the reduction is more than enough to make 2020 particulate concentrations lower than 2019 levels. Still, the improvement in air quality isn't all that dramatic and is already showing signs of disappearing.