My sensor (“Seward” in Minneapolis) is currently showing PM levels of zero. Granted, this is a rare good air quality night even in the highly polluted neighborhoods nearby, but that still doesn’t seem credible. I’m near a highway, for example.
My sensor was unplugged for a while recently and only just turned back on, so I wonder if it got messed up somehow. Is there a way to reset it?
Do you have any other sensors nearby to compare with? That isn’t necessary a reliable indicator as very local sources of pollutants (chimneys etc) can have a big impact on localized pollution, but it may give you an idea.
If you look at the PurpleAir map and set it to one of the Particle options e.g. Particle>=0.3um, does it register a count?
I’ve seen a rare, actual zero now and then. I think the bad 5003’s that were going out for a while are prone to erroneous zero readings more often. If you are upwind from the highway (and polluted neighborhoods nearby), they might not matter. Knowing the Twin Cities, good air is likely to come on the heels of a North, Northwest wind.