The HEPA (High-Efficiency Particulate Air) filter used in hospital isolation rooms is designed to remove particles of what size with ≥99.97% efficiency?

• A Particles ≥10 µm (PM10)
• B Particles ≥2.5 µm (PM2.5)
• C Particles ≥0.1 µm (ultrafine particles)
• D Particles ≥0.3 µm (MPPS — most penetrating particle size) ✓

Explanation

HEPA filters are certified to capture ≥99.97% of airborne particles at 0.3 µm diameter, the 'most penetrating particle size' (MPPS) — the particle size at which filter penetration is maximum. Larger particles are captured by inertial impaction and sedimentation; smaller ultrafine particles are captured by diffusion. HEPA filtration is a key component of airborne infection isolation (AII) rooms for TB and measles in hospitals, providing ≥12 air changes per hour.

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.