On the average provides the greatest protection, usually seal most reliably, and provides some eye protection as well. Fits over the nose, mouth, and under the chin. Hood or Helmet Loose-fitting respirators that enclose at least the head. A light, flexible device covering only the head and neck, or head, neck, and shoulders is called a hood. If rigid headgear is incorporated into the design, it is called a helmet.
Blouses extend down to the waist, and some have wrist-length sleeves.
The enclosure includes a system through which clean compressed air is distributed around the breathing zone. It may include a head harness and connection for a breathing tube. Mist respirators with replaceable filters Designed as respiratory protection against mist of materials having an air contamination level not less than 0.05 milligram per cubic meter or 2 million particles per cubic foot. Mouthpiece respirators should provide a good seal, but they eliminate communication, may cause fatigue, and provide no eye protection. Therefore, mouthpiece respirators are certified for use as escape-only respirators.