FAQ

When we talk, shout, sing, cough, sneeze or simply breathe, we exhale small aerosol particles (“aerosols”) that are made of saliva or respiratory fluid (the liquid that wets the inside of your trachea, lungs, etc.). These exhaled aerosols may carry a pathogen that can infect others if they inhale it. 

Many respiratory viruses, including influenza viruses, rhinovirus, respiratory syncytial virus, coronaviruses (SARS-CoV-2 and others), spread through the air. Other viruses, such as measles virus and varicella zoster virus, which causes chickenpox, also spread through the air. These pathogens may also spread through large respiratory droplets that are sprayed onto someone’s eyes, nostrils, or mouth or through surfaces that become contaminated with the pathogen. The bacterium that causes tuberculosis, Mycobacterium tuberculosis, spreads through the air, as does Pseudmonas aeruginosa, a bacterium that can cause pneumonia, mainly in immunocompromised individuals. The bacterium Legionella pneumophila spreads through the air from contaminated water. 

There are many different interventions that can reduce the risk of airborne transmission. Their effectiveness varies, depending on the situation and the transmissibility of the pathogen. There are three major categories of interventions. 

1)    Source control. Reduce the number of people present or require testing to reduce the chances that someone who is infected is present. Require people to wear masks to reduce the amount of their respiratory aerosols that are released into the air. Encourage the use of quiet voices instead of singing and shouting, as the number of respiratory aerosols emitted increases with loudness. Instruct people to practice respiratory etiquette by covering their coughs and sneezes. 

2)    Environmental control. Relocate the event outdoors, where pathogens are diluted in air much more than indoors. Indoors, increase the ventilation rate by opening windows and doors and adjusting the HVAC system. Apply filtration indoors through upgraded HVAC filters and/or the use of portable air cleaners. In high-risk areas, use germicidal UV treatment to kill pathogens in the air. 

3)    Personal protection. Wear a high-quality, well-fitting mask such as an N95, KN95, or KF94. Minimize time spent in crowded spaces. Maintain distance from others.