Why Particles Matter

Particles are Everywhere

I’ll never forget the morning I woke up and the sky was red. It was during the worst of last year’s wildfires. I took the photo above. 

Airborne particles matter for air quality, both on the inside and outside of a building. Some particulate matter is so small that the human lungs cannot expel the particles after they have been inhaled.  This ultra-small particulate matter is referred to as non-respirable particles. This small particulate matter is of the most concern for health.

There is a wide variety of airborne particulate matter that can be organic like mold, bacteria, and viruses; or inorganics like ozone, smoke, and other air pollutants.

Particulate matter is separated into respirable and non-respirable groups. Non-respirable particulate matter is able to enter your lungs and embed itself in the lung tissue rather than being released after exhalation. Both the size as well as the chemical composition of particles determines the effect they have on your health.

Particle sensors available to the public are limited, but this is an ever-changing and constantly developing field. The ability of these publicly available monitors ranges in their ability and reliability. The majority of particle sensing devices that only test for “coarse” (over 2.5 µg/m3) particles. Those sensors are significantly less expensive than the sensors with the ability to detect “fine” (under 2.5 µg/m3) particulate matter. The smaller particulate size is of more concern to health and overall air quality. This should be taken into consideration when purchasing a monitor as well as interpreting the results yielded by each monitor.

In recent years, California has experienced devastating wildfires that have negatively impacted the air quality. During wildfires, this app is a very helpful resource: EPA Smoke Sense Study.

Another resource for outdoor air quality is an AI prediction of indoor air by a street address that can be found here: Breezometer.

Here’s a link to the EPA outdoor air sensors in Northern California.

How To Improve Your Indoor Air Quality

Industry-standard equipment utilizes a true-HEPA filter. HEPA is a rating, not a brand; it stands for High-Efficiency Particulate Air filtration. This filters out 99.97% of all particulate matter in the air 0.3µ diameter or greater.


Air purification machines sometimes also have the optional availability of adding a charcoal filter adjacent to the HEPA filter. The charcoal or carbon traps vapors (gasoline, smoke, etc.) and other odors.


Alternative air purification machines can include UV light, ultrastatic filtration, ion generators, or other means. These alternative filtration methods are not recommended. A true-HEPA filter with an additional charcoal filter will not add anything to your indoor air – it will only remove particles and not add extra contaminants to the air.