SEATTLE -- The ash falling from wildfires onto cars and patio furniture around Puget Sound can be psychologically impactful, but it's not as dangerous as what you CAN'T see in the air.
When organic plant material burns, most often it creates very microscopic particles that are in the smoke that billows out of wildfires. Scientists call them PM 2.5, which stands for Particulate Matter that's 2.5 microns or smaller. To get an idea of how small that is, imagine the width of a single human hair. A PM 2.5 would be about 30 times smaller than that width.
That's one of the reasons why those particles sneak through the screens in your home and through most face masks because they're smaller than dust. In your body, they can get past the hairs in your nose, which are there to prevent you from breathing in dirt and dust.
The PM 2.5 pollution can get past the body's mucus defense that is there to trap most tiny foreign invaders. Once you breathe it in, it can get into your lungs and bloodstream.
Some environmental groups say that after smoking, poor diet, and high blood pressure, PM 2.5 pollution is the fifth biggest killer globally. It's estimated to be responsible for 42 million deaths from long-term exposure to PM 2.5.
"If you are going to be spending a significant amount of time outside, consider getting an N95 or P100 mask that are able to filter out the inflammatory particles that are in the smoke," says Dr. Tuan Ngyune, who works in the Swedish Issaquah campus. "Otherwise, we recommend limiting your time and your physical activity outside."