A respirator is a device designed to protect the wearer from inhalation of harmful substances.

When chosen correctly and used properly, respirators can protect the wearer from,

  • Fumes and smokes (welding fume)
  • Harmful dusts (lead, silica, and other heavy metals)
  • Gases and vapors (chemical exposures)
  • Oxygen deficiency (oxidation, displacement, and consumption)
  • Biological hazards (tuberculosis, whooping cough, flu viruses)

Inspection

Users must inspect their respirators before and after use. Respirator inspections must include checking that;

  • Sealing surface are clean and free of cracks and holes
  • Rubber and elastic parts have good pliability and no signs of deterioration
  • Inhalation and exhalation valves are clean and seated properly
  • Straps are sufficiently elastic and free of worn areas
  • If full face, face shield is cleaned and clear (no smudges, scratches, or other damage that may impede visibility)

Respirators that fail an inspection must be removed from service and replaced.

Before using a respirator, the wearer must perform a positive and negative pressure check. The wearer must ensure current facial condition will allow an effective seal (for example the wearer must be clean shaved).

Positive pressure check. Close off the exhalation valve with palms and exhale gently. No leakage outward around the seal should occur.

Negative pressure check. Close off the cartridges and inhale. The respirator should collapse slightly on the face. No leakage around the face seal should occur while maintaining a negative pressure inside the respirator for several seconds.

Maintenance

Cleaning

Respirators must be cleaned and disinfected after each use as follows:

  • Remove filters or cartridges.
  • Disassemble and wash with mild dishwashing detergent in warm water, using a soft brush.
  • Thoroughly rinse to remove any detergent residue.
  • When the cleaner used does not contain a disinfecting agent, respirator components must be immersed for two minutes in a sodium hypochlorite (30 mL household bleach in 7.5 L of water) solution, or other disinfectant. The solution used to clean the respirator(s) should contain some type of biocide for disinfection. Rinse in fresh, warm water.

Do not use organic solvents to clean a respirator or high heat to dry it, as this may damage the elastomeric face piece.

Cartridges and filters

  • Change cartridges and filters according to the specific schedule provided with the authorization, or sooner if you experience an increased resistance in breathing or when you detect contaminant odors or taste while wearing your respirator.
  • General guidance for organic vapor cartridges. Lab users who use respirators intermittently and perhaps in different environments should never reuse organic vapor cartridges after one use. This is due to chemical desorption of the vapors/gases and their migration through the cartridge charcoal bed. When this occurs, contaminants could be inhaled by the respirator wearer upon initial donning and the concentration could even be higher than contaminant concentrations found in the ambient workplace atmosphere.
Replacement and repairs

Repair of respirators may be done only by experienced personnel with parts designed for the specific respirator needing repair. No attempt may be made to replace parts or to make adjustments or repairs beyond the manufacturer’s recommendations.

Storage

  • Store respirators away from dust, sunlight, heat, extreme cold, excessive moisture, damaging chemicals, or contamination.
  • Filters and cartridges must be removed from the respirator and stored in separate bags to prevent cross contamination.
  • Do not store items on top of respirators, which could deform the shape of the face piece.
  • Do not store respirators in such places as lockers or tool boxes unless they are on a separate shelf or in carrying cases or cartons to preserve the shape of the face piece.
  • Respirators must be packed and stored according to the manufacturer’s instructions.
  • Never store a respirator within a fume hood or at a work bench where contaminants are present.

Maintenance and Care of Dust Masks

Dust masks must be maintained in a clean and sanitary condition. Users who wear dust masks must

  • Store dust masks in a plastic bag or box in a secure location such as a locker or desk drawer, away from moisture and contamination.
  • Not share dust masks with others.
  • Not use a dust mask that is torn, distorted, or dirty.

Types of Masks

Table 3.4 displays the types of masks:

Table 3.4 Types of Masks

Dust mask

The use of the term “dust” mask for the non-rigid soft felt mask is somewhat of a misnomer since, in modified forms, they can be used for other applications such as limited protection against paint fumes, moderate levels of organics, acid fumes, mercury, etc., although their biggest use is against nuisance dust.

Half face respirator

The half-face cartridge respirator is the type most frequently used, especially in atmospheres in which there is little or no problem of irritation or absorption of material through the skin.

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Full face respirator

Full-face air-purifying respirators are similar in many respects to half-face respirators, with the obvious difference that the mask covers the upper part of the face, protecting the eyes.

(Images courtesy of Egebant)

Dust mask

The use of the term “dust” mask for the non-rigid soft felt mask is somewhat of a misnomer since, in modified forms, they can be used for other applications such as limited protection against paint fumes, moderate levels of organics, acid fumes, mercury, etc., although their biggest use is against nuisance dust.

These units are the simplest form of the air-purifying respirator. These respirators normally should not be employed for hazardous dusts, but are helpful for exposures to inert or nuisance dust levels below 15 mg/m3.

Half face respirator

The half-face cartridge respirator is the type most frequently used, especially in atmospheres in which there is little or no problem of irritation or absorption of material through the skin. The face piece of most of these units is molded of a flexible plastic or silicone rubber, which provides a seal to the face when properly adjusted. As noted earlier, facial hair between the mask and the face will prevent the seal from being effective, and it is not permitted for a person with a beard or extended sideburns in the area of the seal to be fitted with a respirator. Accommodation for individuals who wear glasses also must not break the seal to the face. The face pieces of most brands of these units are provided with receptacles for two sets of cartridges and/or filters. The respirators are certified as complete units, i.e., the face piece equipped with specific filters. Cartridges from one vendor cannot be used on another manufacturer's face piece. The major advantage of this type of unit is that by interchanging cartridges and filters, or by using one or more additional filters and cartridges in series, a single face piece can be adapted to provide protection against a large variety of contaminants.

Full face respirator

Full-face air-purifying respirators are similar in many respects to half-face respirators, with the obvious difference that the mask covers the upper part of the face, protecting the eyes.

References and sources for information from the relevant websites and documentation of different universities, NGOs and government agencies used in the preparation of this website are provided at references.