In air quality assessment, PM2.5 is considered more hazardous than PM10 primarily because:
- A PM2.5 contains heavier metals such as lead and cadmium in higher concentrations
- B PM2.5 penetrates beyond the trachea into alveoli and can enter the systemic circulation ✓
- C PM2.5 triggers a stronger Type I hypersensitivity reaction in the upper airways
- D PM2.5 is a photochemical oxidant that depletes stratospheric ozone
Correct answer: B. PM2.5 penetrates beyond the trachea into alveoli and can enter the systemic circulation
Explanation
Particulate matter ≤2.5 μm (PM2.5) are fine particles that evade mucociliary clearance and deposit in the respiratory bronchioles and alveoli, where they can translocate across the alveolar-capillary barrier into the bloodstream, reaching the heart, brain, and other organs. PM10 (particles ≤10 μm) are filtered in the upper airways and bronchi. This deeper penetration explains PM2.5's association with cardiovascular disease, stroke, and systemic inflammation beyond the respiratory system. PM2.5 is classified as a Group 1 carcinogen by IARC.
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.