COVID factsheet

From DHS

a flier about basic COVID-19 precautions - particularly for small events/gatherings. All the icons and entire flier are CC0/public domain/free to use: less COVID  

How to control airborne viruses

Excellent overview with links from Joey Fox

Respiratory pathogens, including influenza, COVID-19, RSV, measles, tuberculosis, and the common cold, primarily spread through the airborne route.

When an infectious person breathes, talks, sings, coughs, or sneezes, they release respiratory particles from their mouth or nose that can contain infectious viruses or bacteria. Larger respiratory particles fall to the floor quickly. Smaller respiratory particles, which are called aerosols, can float in the air. The main way most people get infected with respiratory pathogens is by inhaling a sufficient dose of infectious respiratory aerosols over time. This is known as airborne transmission, aerosol transmission or inhalation transmission.

Transmission of airborne diseases happens when people share air. The main risk for airborne transmission is:

• short-range airborne transmission: when you are within about two meters from an infectious person.
• shared-room airborne transmission: when you share a room with an infectious person. This is the cause of super-spreader events where many people can get infected at once. Smaller rooms, crowded spaces and poorly ventilated areas create higher risk for transmission.

The dose makes the poison.

The higher the dose, the greater the risk of infection. A model of how this works can be seen in this publication.

The Relative infection risk parameter increases with 

• higher virus emission, 
• higher activity, 
• higher breathing rate and 
• duration of exposure. 

It decreases with 

• better masking and 
• better air cleaning.