Clinical meaning
Airborne precautions prevent transmission of infections spread by airborne nuclei - tiny particles (≤5 micrometers) that remain suspended in air for extended periods and can travel long distances on air currents. Key airborne diseases include tuberculosis (TB), measles (rubeola), varicella (chickenpox), and disseminated herpes zoster. These particles can be inhaled by susceptible individuals who have never entered the patient's room if air is shared through ventilation systems. Airborne isolation requires a negative pressure airborne infection isolation room (AIIR) that maintains at least 6-12 air exchanges per hour with air exhausted directly outside or through HEPA filtration. Healthcare workers must wear N95 respirators (or higher) that have been individually fit-tested to ensure a proper facial seal, as standard surgical masks do not filter particles small enough for airborne transmission.
Exam relevance
Risk factors: - Undiagnosed or untreated active pulmonary tuberculosis - Immunocompromised patients susceptible to varicella or measles - Healthcare workers without immunity to measles or varicella - Failure to properly fit-test N95 respirators - Rooms without negative pressure capability