Which particulate matter is most harmful due to deep penetration in lungs?
PM2.5 comprises particles with aerodynamic diameters at or below 2.5 micrometres. Their small size allows them to evade much of the upper respiratory filtration, penetrate into bronchioles and alveoli, and in some cases contribute components to systemic circulation. PM10 includes larger particles that are more often deposited in the nose and conducting airways, although it also remains harmful. At organismal level, respiratory surfaces are especially exposed because large volumes of air contact thin, moist epithelia designed for rapid gas exchange. Sound classification links the source, atmosp
Ref: Campbell Biology, Urry et al., 12th Ed., Unit 8 Ecology