https://www.siliconvalley.com/2020/09/24/larry-magid-monitoring-and-cleaning-your-air/

As I write, the air quality in most of Northern California is pretty good but it was horrible about a week ago and could get bad again during the rest of the fire season.  A few weeks ago I wrote about various government and privately-owned air monitors in our communities, including

ones from the Purple Air, that can be installed in people’s yards or inside their homes. I’m fortunate enough to live near a couple of those sensors that my neighbors have purchased and installed, but many people live miles from the nearest sensor, so the data they get may not reflect their immediate environment.