Mandatory signs endorse a particular conduct. This required sign endorses that light breathing assurance (dust cover) must be worn. Use a dust mask. Signs with the message "Wear dust mask"—which indicates that wearing a dust mask is required—are used to be placed in strategic locations to remind and guarantee that people wear them. A safety sign that reads "Dust Mask Shall Be Worn" is used to warn people approaching a certain location that they need to wear respirators or dust masks to protect their lungs from dust particles in the air. This indicator is usually present in areas where there is a chance of being exposed to dust, which over time could be harmful to respiratory health if breathed in. These signs are frequently placed in locations such as manufacturing plants, construction sites, or areas where tasks like grinding, sanding, or cutting are carried out to make sure employees take the necessary safety precautions against dust in the air.