PM2.5 refers to particulate matter with aerodynamic diameter of 2.5 μm or less. The primary reason PM2.5 is more hazardous than PM10 is that PM2.5:

• A Contains more heavy metals per unit mass
• B Penetrates beyond the terminal bronchioles into alveoli and can enter the bloodstream ✓
• C Is invisible to the naked eye, making exposure assessment difficult
• D Primarily originates from tobacco smoke while PM10 comes from road dust

Explanation

PM2.5 (fine particles) penetrate deep into the respiratory tract, reaching alveoli (PM10 is largely deposited in the upper airways and tracheobronchial tree). Fine particles can cross the alveolar-capillary membrane and enter systemic circulation, causing cardiovascular effects, neurological effects, and systemic inflammation in addition to respiratory disease. The NAAQS (India) for PM2.5 is 60 μg/m³ (annual) and 24-hour standard is 60 μg/m³.

Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.