Airborne precautions are required to protect against airborne transmission of infectious agents.

Diseases requiring airborne precautions include, but are not limited to: Measles, Severe Acute Respiratory Syndrome (SARS), Varicella (chickenpox), and Mycobacterium tuberculosis.

Preventing airborne transmission requires personal respiratory protection and special ventilation and air handling.

How airborne transmission occurs:

Airborne transmission occurs through the dissemination of either:

  • airborne droplet nuclei (small-particles [5 micrograms or smaller] of evaporated droplets containing microorganisms that remain suspended in the air for long periods of time) or
  • dust particles that contain an infectious agent

Microorganisms carried by the airborne route can be widely dispersed by air currents and may become inhaled by a susceptible host in the same room or over a long distance form the source patient – depending on environmental factors such as temperature and ventilation.

Airborne precautions include:

  • Standard Precautions

  • Personal respiratory protection
    • N95 respirator
      Prior fit-testing that must be repeated annually and fit-check / seal-check prior to each use.


    • Powered Air-Purifying Respirator (PAPR)

  • Airborne Infection Isolation Room (AIIR)
    • At a minimum, AIIR rooms must:
      • Provide negative pressure room with a minimum of 6 air exchanges per hour
      • Exhaust directly to the outside or through HEPA (High Efficiency Particulate Air) filtration

Airborne precautions apply to patients known or suspected to be infected with microorganisms transmitted by airborne droplet nuclei.