PM10 consists of tiny solid and liquid particles that come from a myriad of sources, both natural and human-caused. "PM" stands for "particulate matter." PM10 particles range in size over many orders of magnitude. They are divided into a fine fraction (less than 2.5 micrometres, called "PM2.5") and a coarse fraction (2.5-10 micrometres). PM10 includes PM2.5 and coarse PM.
The chemical composition of particulate matter is highly variable, depending on the source of the material. A significant portion is formed by chemical or physical processes in the atmosphere, while other kinds of particles are emitted directly from their source. In short, particulate matter is mixture of particles of many sizes, compositions and origins.
Due to its small size, particulate matter can be inhaled, triggering health problems. In the early 1990s, the focus was on PM10. More recent research has shifted to the study of PM2.5 because of its ability to travel farther than PM10 into the human body.
The level for PM10is intended to be equivalent to a maximum acceptable level in the national air quality objective system.
Provincial Ambient Air Quality Objective: PM10 |
||
---|---|---|
Criteria | Level | Averaging Period |
Air Quality Objective | 50 µg/m3 | 24 hours |