PM10: inhalable particle pollution
Understand what PM10 includes, how dust can affect it and why PM10 and PM2.5 are reported separately.
A wider size range
PM10 measures the mass of airborne particles with an aerodynamic diameter of about 10 micrometres or smaller. It includes PM2.5 and the larger fraction between about 2.5 and 10 micrometres. Dust from roads and construction can contribute to that larger fraction, while smoke and particles formed in the air can contribute to the fine fraction.
An episode of transported mineral dust can raise PM10 across a region. A local increase can have other causes. The reported mass by itself cannot tell you what the particles are made of.
Compare like measurements
Compare PM10 and PM2.5 only when both refer to the same location, hour, units and source. A larger difference between the two indicates more mass in the coarser size range when the readings are directly comparable. It takes additional information to attribute that difference to a particular event or source.
The European AQI uses its own bands for PM10. If a station publishes a daily PM10 sample, read that period separately from the hourly index.