Full-face reusable respirators cover the entire face to provide breathable air and protect eyes from irritation caused by gases, vapors, and airborne particles. Respirators are NIOSH-rated to identify the level of protection provided. Reusable respirators use cartridges and filters that can be customized to filter specific hazards. They can also be changed when they become dirty, allowing the mask to be reused. They are commonly used in caustic environments where eye protection is needed, such as chemical manufacturing.