Half-mask respirators are reusable, NIOSH-rated air-purifying devices that protect the respiratory tract from exposure to harmful substances including dust, fog, fumes, mist, smoke, sprays, vapors, gases, and particulates. Half-mask respirators fit over the nose and mouth but do not protect the eyes or upper part of the face. They are National Institute for Occupational Safety and Health (NIOSH)-rated and have an Occupational Safety and Health Administration (OSHA) Assigned Protection Factor (APF) of 10. They may be constructed of silicone, thermoplastic, or rubber materials to allow for repeated cleaning, disinfection, storage, and reuse.

Half-mask respirators are used with exchangeable cartridges or filters that are designed to eliminate specific particulate or chemical substances. Some masks are pre-assembled with permanently attached cartridges. Filters and cartridges are designed for specific respirators and are not interchangeable with every respirator model or type.*

Half-mask respirators are available in  small, medium, and large sizes but may be available as combined, small/medium, or medium/large sizes. They can be worn with safety eyewear or prescription eyeglasses if they do not interfere with the sealing surfaces or head straps. They can also be worn with hard hats, hoods, or face shields and are available with standard or drop-down head harness options. The drop-down design allows workers to communicate outside a contaminated area without totally removing the respirator.

Standard and adjustable harnesses and straps are made of durable, flexible material such as polyester, elastic, nylon, or rubber for a secure fit. If the half-mask respirator has adjustable straps, users may adjust them without completely removing the respirator.

Half-mask respirators used in industrial settings feature an exhalation valve to allow exhaled air to escape through the valve. However, half-mask respirators with exhalation valves should not be used in surgical or medical settings because unfiltered air coming out of the exhalation valve may contaminate the environment.

OSHA requires half-mask respirator fit testing before use and on a consistent, annual basis thereafter. Wearers should inspect half-mask respirators before each use to determine whether or not the respirator is complete and undamaged and to verify that the sealing material properly adheres to the face.

*Regulatory compliance details and filter/cartridge compatibility can be obtained at the individual product level.