Clinical meaning
Airborne transmission occurs when pathogens are carried on droplet nuclei (less than 5 micrometers) or dust particles that remain suspended in air currents for extended periods and can travel long distances within air handling systems. The three primary airborne-transmitted diseases requiring airborne precautions are Mycobacterium tuberculosis, varicella-zoster virus, and rubeola (measles) virus. Tuberculosis bacilli are inhaled into terminal alveoli where they are engulfed by alveolar macrophages; in immunocompetent hosts, T-cell-mediated immunity contains the infection within granulomas (latent TB), while in immunocompromised hosts or with overwhelming exposure, progressive primary disease develops with caseating granulomas, cavitation, and tissue destruction. Airborne precautions require a negative-pressure airborne infection isolation room (AIIR) with 6-12 air changes per hour exhausted directly outside or through HEPA filtration, and healthcare workers must wear fit-tested N95 respirators or powered air-purifying respirators (PAPRs). The nurse implements and monitors airborne precautions, ensures proper N95 fit, monitors negative pressure in the isolation room, coordinates care to minimize door openings, manages TB screening and treatment adherence, and educates patients about respiratory hygiene and the rationale for isolation.