Masks are commonly worn in various situations, including:

- Medical settings (hospitals, clinics)
- Surgical procedures
- Crowded public places (airports, trains)
- During pandemics or outbreaks
- In polluted environments
- For dust protection (construction, gardening)
- In theaters and performances
- For costume parties and events
- In spiritual or cultural ceremonies
- For personal protection (flu season, allergy season)

Note that specific situations may vary depending on cultural, social, or medical contexts.