How do loose-fitting respirators offer protection?
Loose-fitting respirators provide filtering of the ambient air, with a power unit to deliver filtered air to a head top. Unlike tight-fitting respirators, such as half masks and full face masks, they do not create a tight seal with the wearer’s face. Loose-fitting powered respirators instead create and maintain an atmosphere of positive pressure within the head top to reduce the inward leakage of contaminated air, in order to offer respiratory protection to the marked level.
EN 12941, the European standard for powered filtering devices incorporating a helmet or hood, sets out three performance classes:
- TH1 – Low filter performance (90% minimum efficiency)
- TH2 – Medium filter performance (98% minimum efficiency)
- TH3 – High filter performance (99.8% minimum efficiency)
The inward leakage limit for each class is 10%, 2%, and 0.2% respectively. Each class of powered respirator are available with particulate, gas, and combined filters, for protection against the same forms of hazard as half and full face masks.
Facial hair and fit testing
Loose-fitting respirators can provide a solution to the clean-shaven requirement for tight-fitting RPE. Powered air head tops are suitable for use by staff with neatly trimmed, well-groomed facial hair, whereas half and full face masks require the wearer to be clean-shaven in the face seal area. Due to the way the products function, providing facial hair does not affect the fit of the respirator skirt or interfere with any valves within the head top, loose-fitting respirators can be used with beards and other facial hair.
The positive pressure system which enables loose-fitting RPE to offer protection also means there is no requirement for face fit testing. The respirator does not create a tight seal with face, and instead relies on enough filtered air being provided to prevent hazardous substances leaking in. Powered air respirators deliver a specified volume of filtered air, depending on performance class, and include test functions to check airflow.
Comfort and other suitability factors
Comfort can be a consideration in the choice between tight- and loose-fitting RPE. Where the task involves a medium work rate, with sustained hand and arm work such as sawing or handling material, loose-fitting respirators can provide a more comfortable option. In situations with a high work rate – heavy manual work, such as shovelling or climbing – powered respirators (or breathing apparatus) are recommended.
Wear time can also determine the need for loose-fitting respirators. Tight-fitting, non-powered respirators are designed to be worn for short periods with breaks. This means that wearers can become uncomfortable and fatigued if masks are worn for longer periods. Considering loose-fitting RPE for wear times over an hour can help to keep wearers comfortable and prevent RPE being removed or loosened.
Loose-fitting respirators can provide compatible protection against a range of hazards. Safety helmet and faceshield head tops are available to provide combined protection, helping to reduce issues of incompatibility and further increase wearer comfort.
Powered filtering devices incorporating a helmet or hood can be selected in place of the equivalent tight-fitting RPE in many cases where facial hair, fit testing, or comfort factors present an issue. There are also situations in which loose-fitting RPE is recommended, where high work rate or long wear time can require power-assisted filtering. Find out more about our range of loose-fitting respirators. Have any more head protection questions? Take a look at our respiratory protection faq!