When we cough or sneeze, we emit droplets that can carry bacteria or viruses, which can cause diseases.
Masks are designed with a fine mesh that stops these droplets from passing through, preventing diseases from spreading to other people.

There are lots of different types of masks, including disposable masks made of non-woven fabrics*, fabric masks that can be washed and reused, and masks made of polyurethane. Even masks made from the same material can have different mesh sizes, antibacterial treatment or other special properties.

*Non-woven fabrics: fabrics made by sticking fibers together into a sheet rather than weaving them together