One thing I noticed about the one I have outside (and it was noted in the instructions) is they will see fog as pollution. The past two days we've had 95-99% humidity here and its reflected in the readings for sure.
Would be nice if they could somehow fix that, but since it is detecting particulate in the air, I guess that shows its working properly, after all. And having it disable or somehow recalculate at high humidity wouldn't work either when its raining instead of fog, obviously. Just something to look at when looking at the readings.
Besides that it works really well and the little panel on it keeps the batteries up no problem, even though where I have it only has about 90 minutes straight exposure daily. Its been through a few days without much sun and the battery is still showing full.
I should note I have the Ambient Weather version but I'm guessing its pretty similar.