What is PM2.5?
Hazardous airborne particles and chemicals can come in a variety of forms, and from a variety of sources, even some natural ones. Wind-blown desert and mineral dust, wildfires, volcanoes, and even sea spray — these can all cloud the air and make people sick.
But when scientists talk about air pollution, they’re generally thinking about those sources and variants that arise from human activity: things like sulfur dioxide from power plant and other emissions, nitrogen dioxide from vehicle exhaust, and ground level ozone — as well as particulate matter. That last category is crucial, because it’s the microscopic stuff that can actually slip past the respiratory system’s defenses and cause both acute, short-term impacts, and over time, chronic diseases that kill.
The smaller the particles, the more worrying they are. Particulate matter measuring 10 micrometers or less in diameter — a fraction of the width of a human hair — is referred to as PM10, and it is most often associated with road dust, construction activities, and other sources of coarse, airborne particles that tend to settle more quickly. Fine particulate matter 2.5 micrometers or smaller is more frequently associated with burning things — whether it’s coal in a power plant or gasoline in your car. And at that diminutive size, it can get deep into the lungs and bloodstream, and over time, research suggests, it can ravage the body.
The following short film will give you an idea: