Temtop Air Quality Monitor Professional Carbon Dioxide PM2.5 PM10 Temperature and Humidity Tester Indoor Outdoor Air Pollution Detector w/ Audio Alarm and Data Export (M2000C 2nd)

good

Works well. Very responsive. Appears accurate. I tested it for days in a real world situation of changing dust conditions with results as expected. Battery charge lasts long time

I thought I would give this a try. It seemed to be the most legit PM sensor on Amazon. Out of the box the instructions say you are to run it outside for 6 hours to calibrate the PM sensor. I set it outside the day after it had rained, so the air should be somewhat clean. It went from 50 2.5PM to about 20 2.5PM sitting outside for 6 hours. I bring it indoors and it drops to about to 10 to 13 depending on the room I'm in. I've been running a MERV 17 HEPA filter 24/7 for over a week and it doesn't seem to make much difference in my PM numbers. Sometimes walking around the house it jumps up to 40 2.5PM. the 10PM seemed to be about 1-2 numbers off the 2.5PM reading. If 2.5PM was reading 11, then 10PM would read 13. It's hard to believe this meter is anything but a random number generator.

It works!