The Tribe has operated a PM 2.5 monitor since 2003. The monitor measures the amount of very small particulates in the air, which are the unhealthiest particles. (PM 2.5 is particulate matter smaller than 2.5 microns or thought of another way 30 particles will fit on the diameter of a human hair)
For example smoke carries these particles which gets into your lungs and is impossible to get rid of. These small particles build up over time and can cause asthma suffers and other people to have even greater problems breathing.
Along with the PM 2.