PM10 Coarse Particulate Matter

What it is

PM10 is the category of inhalable particles with diameters of 10 micrometers or less. It includes PM2.5 (the fine fraction) plus larger "coarse" particles between 2.5 and 10 micrometers, sometimes called PM10-2.5. For comparison, a strand of human hair is about 70 micrometers across.

Coarse particles are mostly mechanically generated, things that get ground, crushed, or kicked up. They are heavier than PM2.5 and settle out of the air faster.

Where it comes from

The biggest sources of coarse PM are dust and crushing. That includes unpaved road dust, construction sites, mining, agricultural tilling, quarries, and demolition. Wind erosion of dry soil contributes significantly in arid regions.

Biological material also counts: pollen fragments, mold spores, and bacteria often fall in the coarse range. Sea salt spray near coasts and brake and tire wear from vehicles add to the load. Wildfires and volcanic ash produce both PM2.5 and PM10.

Health effects

Coarse particles mostly deposit in the upper airways, the nose, throat, and large bronchi, rather than the deep lung. They trigger coughing, throat irritation, runny nose, and asthma symptoms. Hospital admissions for respiratory issues rise on high PM10 days.

People with asthma, COPD, and allergies are most affected. Long-term exposure has been linked to reduced lung development in children and increased respiratory mortality, though the evidence is stronger for PM2.5. Workers in dusty trades (construction, mining, agriculture) carry the highest occupational risk, including silicosis and other lung diseases from specific dust types.

How it's measured and typical levels

PM10 is reported in micrograms per cubic meter (µg/m³). Reference monitors weigh particles collected on a filter; low-cost optical sensors estimate concentration from light scattering.

Key benchmarks:

WHO annual guideline: 15 µg/m³
WHO 24-hour guideline: 45 µg/m³
US EPA 24-hour standard (NAAQS): 150 µg/m³, not to be exceeded more than once per year on average over 3 years
The US EPA revoked the annual PM10 standard in 2006 due to insufficient evidence linking long-term coarse PM exposure to health effects on its own.

Typical urban background runs 15 to 30 µg/m³. Dust storms in the Southwest US or the Sahara can push PM10 above 1,000 µg/m³ for hours.

What you can do

On dusty days, close windows and run HVAC in recirculate mode. A standard HEPA filter captures PM10 efficiently. If you live near unpaved roads, construction, or farmland, a MERV 11 or higher furnace filter helps.

Outdoors, an N95 mask blocks most PM10. Even a basic dust mask helps for short exposures like yard work. Wet down dusty surfaces before sweeping or raking. If you work in a dust-generating trade, follow OSHA respiratory protection rules for your specific hazard (silica, wood dust, grain dust, etc.).

Sources

This article is for educational purposes only. Canairy does not provide medical advice, diagnosis, or treatment. Talk to a qualified health professional about your specific situation.