An introduction to particulate matter issues

Particulate matter (PM) refers to discrete particles in ambient air that exist either as solid particles or liquid droplets. The sources of PM are:

• natural, e.g. pollen;
• a combination of natural and man-made in variable proportions, e.g. dust in a park, roadside dust, smoke from vegetation and wood burning; and
• wholly man-made, either: – naturally, e.g. household dust from skin shedding; or – activity-related, e.g. smoking, cooking and barbecuing, vehicle use, industrial activities, etc.