What is particle pollution?
[Back to Top] Particle pollution, also known as particulate matter pollution or PM, is a mixture of tiny solids and liquid droplets suspended in air. Airborne particles are the main ingredient in haze, smoke and airborne dust. Particles are made up of a variety of components and may include acids, nitrates, sulfates, organic chemicals, metals, elements from soil or dust, or allergens (for example, fragments of pollen or mold spores). Particles come in a wide range of sizes. Those less than 10 micrometers in diameter are so small that they can be inhaled into the lungs, potentially causing serious health problems. For comparison, ten micrometers is much smaller than the width of a single human hair, which is ~70 micrometers in diameter. Particles less than 2.5 micrometers in diameter are called “fine” particles and are of special concern because they can penetrate deeply into the lungs. Particles between 2.5 and 10 micrometers in diameter are referred to as “coarse” particles.
