What We Measure: Particulate Matter (PM2.5)

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January 18, 2022

Ever noticed a yellow smog or wildfire haze? That dirty, smoky air is made of particle pollution. Overwhelming evidence shows that particle pollution – especially the smallest particles – can increase the risk of heart disease, lung cancer, and asthma attacks and can interfere with the growth and work of the lungs.

What is PM2.5?
Particulate Matter refers to a mixture of solid particles and liquid droplets found in the air. Some particles like dust or soot are visible to the naked eye, others are so small they require an electron microscope to be seen.


PM2.5 are fine inhalable particles with a diameter smaller than 2.5 micrometers (a human hair has a diameter 30 times larger!). These particles – from exhausts, industrial processes, and smoke – enter indoor spaces through HVAC, doors and windows, and “leakiness” in building structures. Particles can also originate from indoor sources like pollens, mold spores, and cleaning products.

Why measure PM2.5?
PM2.5’s small size allows it to bypass many of our body’s defenses. Unlike larger (and more visible) dust particles, PM2.5 can permeate membranous tissue and travel into the bloodstream and lungs. Short term exposure has been linked to throat irritation, coughing, and difficulty breathing. More serious, long-term health effects can include respiratory problems, heart disease, and cancer.

PM2.5 is especially dangerous for people with heart and lung diseases, older adults, and children, but it has also been proven to affect healthy people.

PM2.5 (1)

The impact of wildfires
While PM2.5s have decreased in the United States over the past decades, wildfire-prone areas see tremendous, episodic spikes. Breathing high concentrations of PM2.5 can increase the risk of asthma attacks, heart attacks, and strokes.

Keep your building healthy
Use air quality data from Awair to monitor PM2.5 and develop indoor air quality purge sequences and policies for high PM2.5 events.