As recommended by the World Health Organisation:
Why?
To protect others and prevent the spread of germs through coughs and sneezes.
Remember, masks are only effective when used in combination with frequent hand washing.
Before putting a mask on, make sure hands are washed.
Make sure there are no gaps between your face and the mask.
Avoid touching the mask whilst using it.
Do NOT:
Share or reuse masks.
Use a mask once wet.
Remove the mask from behind the ears to avoid touching the mask and dispose immediately in a closed bin.
Wash hands.