PM 2.5 Emissions Are Particularly Deadly
Particulate matter includes two major categories, PM 10 and PM 2.5. PM 10 includes particles that are 10 μm (micrometers) or smaller. While these are dangerous, they aren’t the deadliest version.
PM 2.5 is even smaller than PM 10, limited to 2.5 μm or smaller. That’s smaller than 1/28th (or about 3 percent) of the diameter of an average human hair. The small size makes it easier for the PM to get into airways and the bloodstream. Particles of that size have the ability to enter the throat or nose, reach the lungs, and even make their way to the heart or brain. Your body’s natural defenses simply can’t stop particles that are that small.