Why Does The Size Of The Particles In Your Air Matter?

Every time you take a breath, you’re pulling in all sorts of particulate matter into your body. Most are so tiny you’d need a microscope to identify them. 

But, even though you may not be able to see them, when it comes to particles… size matters. Understanding the size of particles can be helpful in both determining what effect they may have on your body and how they can be removed from your air.

What is particulate matter?

No matter how clean you think your air is, you are always breathing in tiny solid or liquid particles called particulate matter or PM. Most of the time you can’t see particulate matter… but sometimes, the concentrations in the air get so high that PM actually becomes visible.

Where does Particulate matter come from?

PM comes from combustion, human and animal shedding, plants, and other sources. They then mix with liquid droplets and get suspended in the air. When there are enough PM in your air, they can cause health issues.

It isn’t just the PM themselves. Particulate matter can also combine with nitrogen and volatile organic compounds in the air to cause even more damage to your health. 

How is particle size measured?

Light is the most common way of measuring particle size, but other technologies that incorporate ultrasound, electric fields, and even gravity are also sometimes used.

Whatever technology is used to measure the particles, the measurement is always indirect… meaning… it’s not a measure of the particle itself, but a measurement of the particle reworked into a standard model. That’s because there is no uniformity to the shape of particles. They’re not perfectly round or square or any other easily measurable shape.

What all this means is that in order to measure them against each other, particles need to be converted into a comparable format. 

In most cases, the particle size is converted into a spherical model, and the diameter is measured in a microscopic unit commonly known as a micron. 

To get a better understanding of the size of a micron it can help to know that a sheet of standard paper is around 100 microns. Anything smaller than 40 microns is invisible to the human eye.

Size matters

The size of particulate matter makes a big difference in how harmful it can be to your health. Let’s take a look at the three size categories most commonly used:

Coarse Particulate matter

The biggest particulate matter is known as PM10, or coarse particles. PM10 is any particulate matter in the air with a diameter of between 2.5 and 10 microns 

Our body has built-in defenses against these larger particles. Typically, we just cough or sneeze them out before they are able to enter more deeply into our bodies. While not as dangerous as smaller particles, coarse particles can still irritate your nose, throat, and eyes and exasperate respiratory illnesses. Although PM10 can reach your lungs, most of it is stopped there. 

Some examples of PM10 include dust from construction sites, landfills and agriculture, wildfires and brush/waste burning, industrial sources, wind-blown dust from open lands, pollen and fragments of bacteria.

Fine Particulate matter

Fine particulate matter, also known as PM2.5 is particulate matter smaller than 2.5 microns. 

Particulate matter of this size is extremely dangerous because it’s able to penetrate deeply into our lungs and even enter our bloodstream.

Fine particles can come from natural or human-made sources including vehicle exhaust, wildfires, factory emissions, and other combustion activities.

Short-term issues from PM exposure include eye, nose, and throat irritation, coughing, sneezing, and shortness of breath. Long-term exposure to PM2.5 can cause permanent respiratory problems such as asthma, chronic bronchitis, and heart disease. PM2.5 particles also increase the likelihood of premature birth and infant mortality.

One study called PM 2.5 “the largest environmental risk factor worldwide,” responsible for many more deaths than alcohol use, physical inactivity or high sodium intake. 

Ultrafine particulate matter

Ultrafine particulate matter or PM1 is particulate matter that is smaller than 1 micron. There is much we still don’t know about PM1, but a growing body of research seems to show that ultrafine dust poses an even worse threat than PM2.5, likely because the smaller particle size is capable of infiltrating our bodies to an even greater extent.

To make matters worse, ultrafine particles represent the majority of airborne particulate matter indoors (up to 90%).

What size are the particles I’m breathing?

Now that you know which size of particles is the most damaging to your health, let’s take a look at some common household pollutants, keeping in mind that they can fall into a wide range of sizes.

Bacteria: 1-10 microns

Viruses: .02-.25 microns

Dust: 1-100 microns

Dust Mite Debris: 0.5 to 50 microns

Human Hair: 70 to 100 microns

Spores from plants: 6 to 100 microns

Tobacco Smoke: .01 to 1 micron

Pollen: 10-1,000 microns

Wood Smoke: 0.4 – 0.7 microns

Pet dander: 5-10 microns

Human sneeze or cough: 5-500 microns

Asbestos: .7 to 90 microns

Mold spores: 4-20 microns

Lead dust: .1-.7 microns

Skin flakes: .5-10 microns

How can I remove Particulate matter from my air?

An air purifier with a True HEPA filter is the most effective way to remove particles of any size. HEPA filters trap particles in different ways according to their size.

Particles larger than 1 micron are heavy enough that the airflow pushes them into the fibers of the filter where they get stuck.

Particles that are .3  to 1 micron can fit in between the gaps in the filter. But, because they are too heavy and slow to follow the airflow around the HEPA filter, they get stuck in the fibers. 

Particles that are smaller than .3 microns are small and light enough that they bounce off larger particles in the air in random patterns, causing them to get caught in the HEPA fibers.

As you can see, an air purifier with a True HEPA filter will be able to remove even the most dangerous sized particles from your indoor air, helping to keep your family safe from harmful pollutants.

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