Airborne precautions are instated for pathogens that are how big?

• A. Small, 5 micrometers or less and can stay suspended in the air
• B. Larger than 5 micrometers
• C. 0.5 micrometers
• D. 10 micrometers

Answer: (A)

Airborne precautions target pathogens that are small enough to stay suspended in air and travel with air currents. The practical threshold is about five micrometers or smaller; particles this size can linger in the air for extended periods and be inhaled deeply into the lungs. Because of that, staff use N95 respirators and patients are placed in negative-pressure rooms to prevent spread through the air. Larger particles, over five micrometers, settle quickly and typically spread by close contact or droplets, which is managed with droplet precautions. So, the defining characteristic is being small enough to remain airborne—five micrometers or less.