Who Does a Mask Protect?

Let’s imagine that a contagious person wears a 50% effective mask. By "50% effective" we mean that wearing this mask cuts in half the chance that this person will infect a nearby susceptible person.

Simulation 1.1

Interaction Type 1: The unmasked contagious person is near an unmasked susceptible person.
Disease transmission does not drop (0%).
Interaction Type 2: The contagious person wears a 50% effective mask.

What if the susceptible person wears the mask instead?

The effectiveness of a mask usually depends on whether you’re inhaling or exhaling through it. Let’s keep things simple and assume that masks are equally effective when we breathe in or breathe out through them.

Simulation 1.2

Interaction Type 1: The unmasked contagious person is near an unmasked susceptible person.
Disease transmission does not drop (0%).
Interaction Type 3: The susceptible person wears a 50% effective mask.

What if both people wear 50% effective masks?

Will the disease not be transmitted to the susceptible person? What evidence do you have?

Simulation 1.3

Interaction Type 1: The unmasked contagious person is near an unmasked susceptible person.
Disease transmission does not drop (0%).
Interaction Type 4: Both people wear 50% effective masks.

Continue to Page 2.