I saw some forum posts about this a year ago but I’m not sure they’re relevant anymore. I just purchased a kit and assembled it letting it run overnight.
PM2.5 is always 0
Highly doubt that’s accurate especially in my musty basement.
You could try taking it outside for awhile and see if the number go up.
Also, with the current devices, they need a batch specific calibration. On the far right of your device click the icon with three dots and select Advanced Settings
Then under PM2.5 Calibration Formula you can pick one of the batch specific numbers. As far as I know, you need to get into the device itself to see the sticker on the PM2.5 sensor to know which batch you have
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