Accuracy of all of them needs to be taken with a grain of salt. As was stated by someone above, think of them as relative measures.
What I do, is I measure the typical ambient readings, and keep on my respirator when producing particles until the count returns to ambient. I focus on the small particle readings, as that's the most harmful.
It's a great, safe approach, unless we have that Saharan dust cloud over us.
- After I ask a stranger if I can pet their dog and they say yes, I like to respond, "I'll keep that in mind" and walk off
- It's above my pay grade. Mongo only pawn in game of life.