Particle counter to confirm the air purifier capability

Particle counter is a machine to check air quality around us.
It can check both PM2.5 and PM10. also can check the fine particulate matter under 0.3μm and 2.5μm。
With laser particle counter can also confirm the air purifer capability.
You can check the air quality before and after you use the air purifier.
Anway, particle counter is the best helper to check the air quality around us.