 Price, a teacher, and her husband only have so much time off, but she knows how damaging particulate matter is to developing lungs, those with respiratory conditions, elders, and others. Particulate matter at the micron level, PM2.5, goes deep into the lungs. And it is small enough that when you breathe it, it goes deep into the alveoli of your lungs, and if it's small enough, it can actually pass right into your bloodstream.