‘We may not even see them, but tiny particles, particulates in the PM2.5 size range, are able to travel deeply into the respiratory tract. PM2.5 infiltrates the lungs, all the way to the alveoli, where oxygen is transferred into the bloodstream. Exposure to nitrogen dioxide and fine particulate matter, or PM, can cause grave trouble with one’s health.’
Source: Air Pollution Increases ER Visits — Largest US Study On The Topic Confirms It | cleantechnica.com