Western First Aid & Safety Blog

Respiratory Hazards and How to Select Respirators

There are many respiratory hazards at worksites: gases, vapors, dusts, mists, fumes, smoke, sprays, and fog to name a few. Some of these substances can make people sick or even cause death if ingested. In fact, respiratory hazards can be especially deadly as they act quickly, like carbon monoxide. Still others take a toll over time, like cancer causing asbestos. Western First Aid is here to help by sharing the Occupational Safety and Health Administration’s (OSHA) examples of respiratory hazards found in general industries. OHSA reports that these can include, but are not limited to:
  • Dusts, such as those found when adding dry ingredients to a mixture.
  • Metal fumes from welding, cutting, and smelting of metals.
  • Solvent vapors from spray coatings, adhesives, paints, strippers, and cleaning solvents.
  • Infectious agents, such as tuberculosis bacteria in healthcare settings.
  • Chemical hazards, such as chlorine gas and anhydrous ammonia in chemical processing and use operations.
  • Sensitizing vapors or dusts, such as isocyanates, certain epoxies, and beryllium.
  • Oxygen deficiency, which might be found in confined spaces.
  • Pharmaceuticals during the production of prescription drugs.
Generally, you’ll find three ways toxic materials enter the body:
  1. Through the lungs (respiratory system)
  2. Through the skin
  3. Through the gastrointestinal tract
Of the three, the respiratory system presents the quickest and most direct avenue of entry. This is due to the respiratory system's direct relationship with the circulatory system and the constant need to oxygenate tissue cells to sustain life. So what can you do to protection yourself and your staff? Choose the proper respirator. Selecting respirators requires knowing what level of respiratory protection employees need, as well as which size respirator is right for the face and facial contours. Respiratory protective devices vary in design, application, and protective capability. To choose the right one, you need to assess the inhalation hazard and understand the specific use limitations of air-purifying and air-supplied respirators. Air-purifying respirators are used against particulates, gases, and vapors. These are categorized as negative-pressure respirators that use chemical cartridges and/or filters; gas masks; and positive-pressure units such as powered air-purifying respirators (PAPRs). Air-supplied devices rely on a primary air source to deliver a steady flow of respirable air to the user's face-piece. These consist of Self-Contained Breathing Apparatus (SCBA) and air-line devices. If your hazard calculation shows that exposure concentrations exceed recommended limits and engineering/administrative controls do not reduce exposure below the permissible limit, you must tailor your respiratory protection program to your specific conditions:
  • Toxicity (TLV – threshold limit value or TWA – time weighted average)
  • Maximum Expected Concentration
  • Oxygen level
  • IDLH (Immediately Dangerous to Life or Health) concentration
  • Warning properties (adequate or not)
  • Sorbent limitations
  • Face-piece fit
  • Mobility requirements
  • Type of use (routine, escape, or emergency entry)

Air-Purifying Respirators

Air-Purifying Respirators (APRs) range from simple disposable cup masks to low-maintenance half-mask face-pieces with cartridges and/or filters to the more complex PAPRs with full-face-pieces, or hoods. •APRs for particulates use filters to capture dusts, mists, and fumes. Filters do not protect against gases or vapors, and generally become less effective as particles accumulate on the filter and plug spaces between the fibers. Filtering APRs require filter replacement when the user finds it difficult to breathe through them.
  • Gas and vapor APRs employ chemical cartridges or canisters to remove hazardous gases or vapors from the air. They do not protect against airborne particles. Made to protect against specific gases or vapors, they provide protection only as long as the cartridge’s absorbing capacity is not depleted.
  • Combination APRs, fitted with both particulate filters and gas/vapor cartridges, are worn in atmospheres that contain hazards of both particulates and gases.
  • PAPRs provide a continuous filtered airflow with a battery-operated blower. Includes a face-piece, hood or helmet, breathing tube, and a canister/cartridge/filter type assembly.

Supplied-Air Respirators

Supplied-Air Respirators (SARs) comprise air-line respirators, SCBA, and combination (supplied-air) respirators.
  • Air-line respirators are used for extended periods in non-IDLH atmospheres. They use a hose (air-line) to deliver clean breathing air from a stationary source of compressed air for prolonged periods of time. Although comparatively lightweight, air-line respirators can limit users’ mobility.
  • Self-contained breathing apparatus (SCBA) have an open-circuit design that provides air rated for 30 to 60 minutes. They consist of a wearable, clean-air supply and a tight-fitting face-piece, and are used for short-duration (30- to 60-minuted rated) work shifts and entrance to or escape from atmospheres that are or may be IDLH. They offer relatively unrestricted movement.
  • Combination SARs are air-line devices used for extended work periods in atmospheres that are or may be IDLH. They have an auxiliary self-contained air cylinder that can be used if the primary air supply fails. The air cylinder can also be used for entry into or escape from IDLH atmospheres, such as confined spaces.
Employers are required to provide employees using SARs with breathing gases of high purity, and ensure that compressed air, compressed oxygen, liquid air, and liquid oxygen used for respiration is in accordance with the specifications of OSHA Standard 1910.134(i). Whether your inspection takes you inside a rail car to examine coatings or through a paint shop, make sure you’re wearing the appropriate respiratory protection. It could be a matter of life or death. If you have questions, you can always ask Western First Aid! Source: MSA

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