



1. Size: "Fine" particulates smaller than 2.5 micro-meters (um) are more dangerous than 10 um PM.

2. Concentration: 45 micro-grams (ug) per cubic meter of Fine Particulates is significantly more harmful than 10 ug per m3.





Typically, the main sources of harmful Fine Particulates are Ammonium Nitrates & Sulfates, Vehicle Emmission, Controlled Biomass fires (such as your grill or your fireplace), and natural dust. During periods when pollution from wildfire smoke becomes a problem, the Uncontrolled Biomass category becomes the largest individual contributor to 2.5 um PMI. To put things in perspective, on a typical August day during the summer of 2018, wildfire smoke was the source of a whopping 73% of harmful particulates.





The takeaway? Normally, there is no dominant source of harmful Fine Particulates. We should all do what we can do reduce ALL sources of air pollution to minimize long term harm. Forest fire pollution, however, can quickly become the single-largest source of pollution in many parts of the country, putting a special emphasis on how important it is to our respiratory health that we mitigate their frequency, duration and growth. Wear a pollution mask if you go outside during wildfire season!

When we talk about air pollution, we will often use the abbreviation PM, which stands for Particulate Matter. There is some amount of natural PM, also known as Particle Pollution, in every breath we take. There are two main factors that tell us whether PM is harmful: