Why particle count matters even when PM2.5 looks clean
19/01/26, 18:00
Understand the difference between PM mass and particle count in your workplace. Learn how tracking sub-micron particles reveals real-time changes in air quality.
Why mass readings don’t tell the whole story
Most air quality monitors report PM2.5, which measures the total weight of airborne particles. While this is useful for regulatory compliance, it can overlook sub-micron particles. These extremely small particles are numerous and can impact health. Air can appear “clean” by PM2.5 readings while still containing millions of invisible sub-micron particles.
Colour-coded air quality guide
Blue: Good
Green: Moderate
Amber: Poor
Red: Unhealthy
Dark red: Hazardous
Why particle count matters
Tracking particle numbers gives a more complete picture of air quality, especially indoors, in urban environments, or during combustion events. Trends in the 0.3 µm, 0.5 µm, and 1.0 µm channels are particularly useful for identifying spikes that may not appear in PM2.5 mass readings.
Use case example
A city-centre office may show “good” PM2.5 levels throughout the day. However, particle count spikes during rush hour reveal sub-micron traffic pollution entering through the ventilation system - something PM readings alone would miss.
Key takeaway
For workplace health, source identification, and filtration checks, businesses should track both PM mass and particle count, giving more weight to particle numbers when sub-micron particles dominate.