The Basics of Respirators

Inhalation is the most common route of exposure for employees to most toxic materials in the workplace.  Selecting and utilizing the appropriate respirator can be quite confusing and difficult.  Employers and employees must get a firm understanding of respirator basic knowledge in order to increase respiratory safety in the workplace.


  • Canister or Cartridge:  a container with a filter, sorbent, or catalyst, or combination of these items, which removes specific contaminants from the air passed through the container.
  • Employee exposure:  exposure to a concentration of an airborne contaminant that would occur if an employee were not using respiratory protection.
  • Fit Factor:  a quantitative estimate of the fit of a particular respirator to a specific individual.
  • Fit Test:  the use of a protocol to qualitatively or quantitatively evaluate the fit of a respirator on an individual.
  • Fogs:  are vapors which have condensed into tiny airborne particles or droplets.
  • Gases:  materials that become airborne at room temperature.
  • Mists and Sprays:  very small droplets of liquid materials suspended in the air.
  • Oxygen Deficient Atmosphere:  an atmosphere with an oxygen content below 19.5% by volume.
  • Service Life:  the period of time that a respirator, filter or sorbent, or other respiratory equipment provides adequate protection to the wearer.
  • Vapors:  substances created when a solid or liquid material evaporates.

Types of Respirators

  • Air Purifying Respirators (APR):  a respirator with an air purifying filter, cartridge, or cannister that removes specific air contaminants by passing ambient air through the air-purifying element.  Cannot and must not be used in oxygen deficient atmospheres!

Types of APRs:

  • Air Purifying Disposable Particulate Respirator
    • i.e. Dust Mask
  • Air Purifying Half-Mask Respirator
    • only covers mouth and nose
  • Air Purifying Full-Face Mask Respirator
    • encapsulates the entire face
  • Gas Masks
  • Powered Air Purifying Respirator (PAPR)
    • uses a blower to force the ambient air through air-purifying elements to the inlet covering.
  • Atmosphere Supplying Respirator (ASR):  supplies the respirator user with breathing air from a source independent of the ambient atmosphere.

Two types of ASRs:

  • Supplied Air Respirator (SAR):  an atmosphere supplying respirator for which the source of breathing air is not designed to be carried by the user.
    • Supplied Airline Respirator
    • Air Cart and Airline
  • Self Contained Breathing Apparatus (SCBA):  an atmosphere supplying respirator for which the breathing air source is designed to be carried by the user.
    • SCBA
    • Escape-Only Respirator

Four Questions Used to Determine Respirator Selection

  1. What type of contaminant is present?
  2. What is the form of the contaminant?
  3. How toxic is the contaminant?
  4. What is the concentration of the contaminant?

 OSHA Respiratory Protection Program Components

  • Written standard procedures governing selection and use of respirators in the workplace
  • Industrial hygiene survey to determine exposure levels
  • Medical evaluation and surveillance
  • Fit testing
  • User training
  • Regular maintenance, cleaning, and disinfecting
  • Proper storage

Please consult with the OSHA standards to get more details of respirator safety.

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