When we inhale, air enters through our mouth or nose into the trachea, a sturdy tube with cartilage rings. These ensure that the airway is always open. It divides into two branches, called bronchi. At the ends of the smallest bronchi are the alveoli. The alveoli pass the inhaled oxygen into the blood. The blood brings oxygen to all the sites in the body.
If the air is polluted, harmful particles are brought with the oxygen during inhalation deep into the bronchi and then into the bloodstream. It should be easy enough to see how this can lead to heart disease and other serious health risks.
How Particulate Matter is Classified
Particulate Matter (PM) is categorized by size: PM10 (0.01mm), PM2.5 (0,0025mm) and PM1 (0.001mm), of which the latter is the most harmful form. After inhalation, these different sizes of particulate matter affect each body in a different way.
PM10: These are particles having an aerodynamic diameter of less than 10 micrometers. These particles are often referred to as “coarse particles” and are composed of fabrics from industrial sources including road contaminates, as well as particles formed by combustion. Depending on their size, the particles tend to remain in the lungs.
PM2.5: Particles with an aerodynamic diameter less than 2.5 micrometers. These particles contain secondary aerosols and combustion particles. Fine particles can reach the pulmonary alveoli.
PM1: Ultrafine particles with an aerodynamic diameter less than 0.1 micrometers. Ultra-fine dust is the most damaging variant of fine particles because the particles penetrate directly through the lungs into the bloodstream and are thus spread to the organs.