Table 1.

Effects of PM on the human respiratory system.

Diameter (μm)	Distribution characteristics	Effects on human physiology
PM10	Deposits in nose and throat	Can cause allergic rhinitis, cough, asthma, and other symptoms
PM2.5−10	Deposits in upper nasal cavity and deep respiratory tract	Causes fibrous paralysis, bronchial mucus hypersecretion, and mucosal gland hyperplasia leading to reversible bronchospasm, inhibits deep breathing and spreading to bronchi
PM2.5	Less than 10% deposits in bronchi, ~20–30% deposits in lungs	Can cause chronic bronchitis, bronchiole expansion, pulmonary edema, bronchial fibrosis, or other symptoms
PM0.1	Deposits inside alveolar tissue	Promotes significant increase in macrophages in the lungs, causes emphysema and alveolar destruction