Aside from trying to buy a commonly used reliable device, that what the match test was for. When my device was reading 12ppm pm2.5 and a blown out match made it

Aside from trying to buy a commonly used reliable device, that what the match test was for. When my device was reading 12ppm pm2.5 and a blown out match made it read in the 100s clearly the device is working to some degree of accuracy. I could've checked it outside I guess but I think local air conditions would predominate over any official city average I could have compared it against.