Join us as we talk with Sotirios Papathanasiou about what’s in the air! Our outdoor and indoor air is filled with particulate matter (PM) that consists of tiny solid and liquid particles that are often invisible to the naked eye. But just because we can’t always see these particles doesn’t mean they aren’t there and negatively affecting our health. In fact, the tinier the particle, the deeper into our bodies it can go! The good news is there are steps you can take to improve your indoor air quality.

Be sure to check out this interview to learn more about how everything from your cleaning products to your humidifier can be contributing to poor indoor air quality and how you can take steps today to improve the air inside your home!

Episode Highlights:

  • How did Sotirios become interested in air quality? 
  • What’s in our indoor air and what is particulate matter? 
  • What is PM10 and PM2.5? 
  • What are examples of particulate matter in our indoor air? 
  • How do these particles enter the body? 
  • Does air pollution kill? 
  • How do you reduce particulate matter in your indoor environment? 
  • How do humidifiers add particulate matter to your air? 
  • Can particulate matter be removed through vacuuming and cleaning?  
  • What are some tradeoffs with energy efficient and tightly built homes? 
  • Final thoughts. 

Links mentioned in interview:

Get in touch with our guest:

Sotirios Papathanasiou

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The average American spends 90% of their time indoors breathing air that’s potentially bad for their health. In fact, the EPA estimates that concentrations of some pollutants indoors are two to five times higher than outdoor concentrations. These pollutants can take many forms and are sometimes known as particulate matter. The bottom line: what’s in your air matters!

What is particulate matter?


Particulate matter (PM), also known as particle pollution, is a mixture of solid and liquid particles in the air that can be easily inhaled. These particles consist of a wide variety of substances that vary in shape, size, and composition. Common sources of particle pollution include dust, pollen, mold, cleaning products, candles, smoke, and vehicle exhaust.


How big is particulate matter?

These tiny particles vary in size and are often measured in a unit called microns (µm). A micron is one millionth of a meter or 1/26,000 of an inch. To put that into perspective, the eye of a needle is roughly 1,230 microns and a strand of human hair is approximately 70 microns in diameter.

Typically, the naked eye cannot see anything smaller than 40 microns. This means that particulate matter from things such as gas stoves, cleaning supplies, candles, and mold are often invisible to the naked eye.

When it comes to indoor air quality, there are three commonly discussed categories of particulate matter: coarse particles that are 10 microns or smaller (PM10), fine particles that are 2.5 microns and smaller (PM2.5), and ultrafine particles that are 0.1 microns and smaller (PM0.1).

How does particulate matter affect your health?

Particles that are PM10 or smaller can penetrate deep into the lungs, while PM2.5 and smaller can cross directly into your blood stream. Basically, the smaller the particle, the deeper it can go into your body!

Graphic shared with permission of #seetheair at

According to the American Lung Association, “Extensive research has linked short-term increases in particle pollution to:

  • increased mortality in infants;
  • increased hospital admissions for cardiovascular disease, including heart attacks and ischemic heart disease;
  • increased hospital admissions and emergency visits for COPD;
  • increased hospitalization for asthma among children; and increased severity of asthma attacks in children.”

The American Lung Association also states, “Research has also linked year-round exposure to particle pollution to:

  • higher likelihood of children developing asthma;
  • worsening of COPD in adults;
  • allowed lung function growth in children and teenagers;
  • increased risk of death for cardiovascular disease; and
  • increased risk of heart attacks and strokes;
  • higher likelihood of getting lung cancer; and
  • higher likelihood of developing diabetes.”

The good news is you can take steps to reduce your exposure to these harmful particle pollution by focusing on source removal, improved filtration, and increased ventilation.