Respiratory Protection

Air-Purifying Respirators and Hoods

Overview

This module introduces respiratory protection in the form of air- purifying respirators (APR) and hooded respirators.  The focus is toward disaster site workers who may be exposed to chemical, biological, radiological, nuclear agents (CBRN), or airborne particulates that may be found at disaster sites.  Remediation that involves demolition will also generate airborne hazards.

Objectives

After completing this module, the participant will be able to:

• Identify if an air-purifying respirator is approved for CBRNE use by NIOSH.
• List the limitations of APRs.
• List the types of APRs.
• Describe some respiratory hazards.
• Explain what must occur before a user can wear a respiratory protection device such as an APR.

Respiratory Protection and CBRNE Agents

A terrorist has attacked your facility, causing an explosion that releases chemicals into the air inside and around the facility.  Do you have respirators on hand to protect emergency responders and the rest of the work force trying to escape?

The answer to that question depends on whom you ask and, to a certain degree, on the type of facility and where it is located.  Terrorists are likely to strike near large population centers, but they also may target a remote chemical facility, for instance, because of the availability of toxic industrial materials or chemicals that could be used in the attack.  No town, city, or state is immune.  Even places that have some level of protection or shield and cannot say, 'It won't happen here.”

Terrorists potentially have numerous chemical, biological, radiological, nuclear and explosive/energetic (CBRNE) agents at their disposal.  The only limitation is the ingenuity of the terrorists who design the attack when they are motivated, have the opportunity, and have a target.

NIOSH Certification

There is no universal type of respirator that is effective against all CBRNE threats, according to respirator manufacturers and the U.S. government, but development of such products is under way by respirator manufacturers.  The military for years has worked at providing soldiers with respiratory protection in the event of a terrorist attack.  The technology is available for industrial use, and NIOSH is working to develop criteria to certify respirator products that will protect against CBRNE agents.

A debate exists as to whether the right kinds of respirators for CBRNE agents already are available.  The certification that NIOSH is developing will not be a magic bullet.  There won't be one respirator that will do everything.

NIOSH in May 2003 certified the first self-contained breathing apparatus (SCBA) for use against CBRNE agents.  In June, stakeholders met in Pittsburgh to begin establishing certification criteria for full-face, air-purifying respirators.  The agency also planned to offer certification for escape respirator hoods and powered air-purifying respirators over the next year or two.  The goal is to certify as many products as possible against virtually all CBRNE hazards.

In any event, terrorist or industrial, you don't necessarily know what you'll find.  You could encounter any of the toxic industrial materials, as well as chemical warfare agents.  The respiratory protection you're offering needs to have some assurance it is capable of meeting this wide spectrum of hazards.

On-Site Chemical or Warfare Agent

Business and industry complying with 29 CFR 1910.134, OSHA's respiratory protection standard for general industry, may be more prepared than they think if a terrorist used large quantities of existing chemicals to fuel an attack.  Facilities with compliant respiratory protection programs likely are prepared for the release of existing chemicals, whether by accident, terrorist activity, or disaster.

Accidental releases of chemicals, however, may be at lower concentrations than releases caused by terrorists or natural disaster.  Today, media contained in canisters exists that will filter out many toxic industrial materials, but not at the potential concentrations that NIOSH believes might happen.  NIOSH is working with the U.S. Army Soldier and Biological Chemical Command (SBCCOM) on hazard mapping to determine potential concentrations if particular chemicals are released by terrorists.  If you don't know the concentration, you're pretty hard-pressed to say a particular respirator filter canister will provide protection.

While the use of WMD agents such as sarin or mustard gas is less likely, respiratory protection for these hazards is harder to prepare for because of not knowing which agent(s) a terrorist will use. NIOSH lists 40 WMD-type hazards, including several biological, chemical, nerve and choking agents.  Respirators typically are stored and distributed as needed; however, respirators for terrorist response need to be readily available.  

What if the threat of a terrorist attack is thought to be extremely low at a facility that has had no need for respiratory protection in the past?  The facility needs to assess whether a threat exists and determine if respiratory protection is feasible and practical.  Unless there's a credible threat, you can't have respiratory protection available for everybody at a low-risk plant.  You need to look at the level of risk and the potential.  If the potential is extremely low, you may not need to do anything.  If the risk is high enough, however, there are steps to take to protect workers.

Responding or Escaping

The type of respirator protection needed in the event of a terrorist attack or disaster event depends on the type of hazard present and whether workers are emergency responders or are part of the work force trying to escape.  Each scenario calls for a specific type of protection.

Responding

For workers who are first responders, wearing an SCBA with an encapsulated suit is a must. If there is a question as to what CBRN agent was used in the attack, whereas the disaster site worker who will respond at a later time to assist or clean up will have the necessary information for proper respirator selection.  Finding out later that a respirator was inadequate could prove fatal.

The job of first responders entering an unknown environment is to assess the hazards and determine whether subsequent responders will need the same full-body protection or whether less physically demanding equipment can be used.  Keep in mind that respiratory hazards are not the only concern for responders to a CBRNE scenario.  Dermal exposure or physical exposure may be the limiting factors.

As the responder's level of exposure decreases, certain types of air-purifying respirators may be adequate.  Powered air-purifying respirators also are candidates for some responders.

Escaping

To protect workers escaping from a terrorist attack, the choice is between a respirator or an escape hood.  Both have advantages and disadvantages.

Respirators.  If escaping from a terrorist attack, only some filter media will protect workers.  Normal air-purifying respirators won't provide the protection needed to escape from CBRNE agents in a WMD scenario.

Respirators for use against CBRNE agents will not be effective unless:

·         The hazard in question has been properly identified.

·         The mask is fitted and used properly.

·         The product is used in areas containing sufficient oxygen.

In addition, a tight-fitting respirator will not provide a proper seal for those with facial hair or who wear glasses.

Escape hoods.  Until recently, escape hoods mostly protected users from smoke inhalation.  It's important that smoke escape hoods not be used for terrorist attacks because they do not provide adequate protection against CBRNE agents.

NIOSH-approved escape respirators may protect from specific chemicals, such as chlorine or sulfur dioxide, but not a majority of hazards.  Escape respirators with more universal protection that are NIOSH-approved have become a real need.  One type of escape hood contains an internal half-mask respirator.  Other hoods contain a mouth bit (some with a nose clip) and cartridge or short-term supplied air.

In addition to filter protection, CBRNE escape hoods need to provide a tight-fitting neck seal, similar to a tight seal for full-face respirators.  The neck seal as an elastic washer that fits over the head, then contracts to the user's neck size.  Long hair needs to fit inside the hood.

Escape respirator devices likely would be used by workers not used to wearing respiratory protection, so training is needed on how to don the product.  It should include checking to see if the user might become distressed or claustrophobic.  Ensure that the user's neck size will fit the range, such as 10 to 22 inches, provided by the product.  Advantages of escape hoods over full-face respirators include fewer restrictions for users concerning facial hair and glasses, an important consideration.

Air-Purifying Respirator (APR)

These respirators remove air contaminants by filtering, absorbing, adsorbing, or chemical reaction with the contaminants as they pass through the respirator canister or cartridge.  This respirator is to be used only where adequate oxygen (19.5 to 23.5 percent by volume) is available.  APRs can be classified as follows:

• Particulate removing respirators, which filter out dusts, fibers, fumes and mists.  These respirators may be single-use disposable respirators or respirators with replaceable filters.
• Gas and vapor removing respirators, which remove specific individual contaminants or a combination of contaminants by absorption, adsorption, or by chemical reaction.  Gas masks and chemical-cartridge respirators are examples of gas and vapor respirators.

• Combination particulate/gas and vapor removing respirators, which combine the respirator characteristics of both kinds of air-purifying respirators.

APRs do have limitations:

• They do not work for all chemical environments.
• They cannot be used in an IDLH atmosphere.
• They can only be used where adequate oxygen exists.
• They cannot be used for CBRNE agents unless NIOSH approved.

 Types of APRs

Respiratory protection is of primary importance since inhalation is one of the major routes of exposure to airborne contaminants.  Respiratory protection devices (respirators) consist of a facepiece connected to either an air-purifying device (cartridge or canister) or an air source.

Different types of facepieces are available for use with the various types of respirators.  The types generally used are full facepieces and half masks.  Full facepiece masks cover the face from the hairline to below the chin.  They provide eye protection.  Half masks cover the face from below the chin to over the nose and do not provide eye protection.

Dust Mask

Another type of APR is a disposable air purifying particulate respirator (dust mask).  Dust masks have the same regulatory requirements as any other APR.  They must be NIOSH approved.  Also, employees wearing dust masks must complete respiratory protection training, undergo medical surveillance, and be fit tested.

Limitations for dust masks are the same as any other APR.  They cannot be used in an oxygen-deficient or enriched environment, or in an IDLH environment.  In addition, they provide protection against a very limited number of specific dusts and mists. 

For initial disaster site operations, dust masks are NOT recommended.  However, during final phase remediation of the site they may become appropriate.  Be sure to check with your supervisor regarding the proper respirator for you job.

Airline and Hoods

 

 

 SARs, sometimes called airline respirators, provide breathing air independent of the environment.  They consist of facemask and compressed air supplied by a compressor or remote cylinder.

SARs also have limitations.  The reach limits of the inline hose not only restrict the distance from the supplied air source, but also limit the wearer’s movement.  Also, only grade D air can be used as the supplied air source.

NIOSH Filter Classifications

• N - For solid particulates and non-oil aerosols that do not degrade filter performance.
• R - For solid particulates and degrading oil-based aerosols. R filters have "Use Limitations."
• P - For solid particulates and degrading oil-based aerosols. P filters have no "Use Limitations" other than those normally associated with particulate filters.

Three efficiency levels: 95%; 99%; 99.97%.

Respiratory Hazards

Air contaminants that pose respiratory hazards can exist in many forms.  Employees need to know what these forms are and their sources for these potential contaminants in order to protect themselves from exposure.  Air contaminant forms, examples of such forms, and the potential consequences of overexposure are listed below.

Dusts

Created when solid material breaks down and gives off fine particles that float in the air before settling by gravity.  Examples:  grinding, crushing, drilling, blasting, sanding, and milling operations.  Overexposure could potentially lead to pneumocosis or the toxic effects of the material.

Mist

Particles formed from liquid materials by atomization and condensation processes.  Examples:  spraying operations, plating operations, and mixing and cleaning operations. Overexposure could potentially lead the toxic effects of the material.

Fumes

Created when solid materials vaporize under high heat.  The metal vapor cools and condenses into an extremely small particle with a particle size generally less than one micrometer in diameter.  Examples:  welding, smelting, and pouring of molten metal.  It is important to note that toxic fumes can result from the burning of non-toxic substances. Overexposure could potentially lead to the toxic effects of the material.

Gases

Substances that are similar to air in their ability to diffuse or spread freely throughout a container or area.  Examples:  oxygen, carbon dioxide, nitrogen, helium and chlorine. Overexposure could potentially lead to the toxic effects of the material.

Vapors

The gaseous states of substances that are either liquids or solids at room temperature.  They are formed when solids or liquids evaporate.  Examples:  gasoline, paint thinner, degreaser solvents. Overexposure could potentially lead to the toxic effects of the material.

Respirator Use

Workers who are required to use respirators must be:

·         Trained such that they can demonstrate knowledge of at least why the respirator is necessary and how improper fit, use, or maintenance can compromise its protective effect

·         Medically evaluated to determine their ability to safely wear the respirator

·         Fit tested to assure the respirator will provide adequate wear-time protection

Proper respirator use includes adequate cleaning and inspection, donning, user seal checks, and doffing.

Cleaning and Inspection

These procedures are provided for employer use when cleaning respirators. They are general in nature, and the employer as an alternative may use the cleaning recommendations provided by the manufacturer of the respirators used by their employees, provided such procedures are as effective as those listed in 29 CFR 1910.134 Appendix B- 2.  Equivalent effectiveness simply means that the procedures used must accomplish the objectives set forth in Appendix B-2, i.e., must ensure that the respirator is properly cleaned and disinfected in a manner that prevents damage to the respirator and does not cause harm to the user.

Procedures for Cleaning and Inspecting Respirators

1. Remove filters, cartridges, or canisters. Disassemble facepieces by removing speaking diaphragms, demand and pressure- demand valve assemblies, hoses, or any components recommended by the manufacturer. Discard or repair any defective parts.
2. Wash components in warm (43 deg. C [110 deg. F] maximum) water with a mild detergent or with a cleaner recommended by the manufacturer. A stiff bristle (not wire) brush may be used to facilitate the removal of dirt.
3. Rinse components thoroughly in clean, warm (43 deg. C [110 deg. F] maximum), preferably running water. Drain.
4. When the cleaner used does not contain a disinfecting agent, respirator components should be immersed for two minutes in one of the following:

1.                          Hypochlorite solution (50 ppm of chlorine) made by adding approximately one milliliter of laundry bleach to one liter of water at 43 deg. C (110 deg. F); or,

2.                          Aqueous solution of iodine (50 ppm iodine) made by adding approximately 0.8 milliliters of tincture of iodine (6-8 grams ammonium and/or potassium iodide/100 cc of 45% alcohol) to one liter of water at 43 deg. C (110 deg. F); or,

3.                          Other commercially available cleansers of equivalent disinfectant quality when used as directed, if their use is recommended or approved by the respirator manufacturer.

5. Rinse components thoroughly in clean, warm (43 deg. C [110 deg. F] maximum), preferably running water. Drain. The importance of thorough rinsing cannot be overemphasized. Detergents or disinfectants that dry on facepieces may result in dermatitis. In addition, some disinfectants may cause deterioration of rubber or corrosion of metal parts if not completely removed.
6. Components should be hand-dried with a clean lint-free cloth or air-dried.
7. Reassemble facepiece, replacing filters, cartridges, and canisters where necessary.
8. Test the respirator to ensure that all components work properly.

Donning and Doffing

A respirator must be put on and worn properly if it is to fit and offer effective protection. Always inspect your respirator prior to donning. Donning instructions, found on or in each respirator package, should be fully explained and demonstrated to the wearer by a competent person.  Once proper donning and adjustment procedures are understood, each wearer will complete the same procedure as trained prior to respirator use. Users must be medically evaluated before donning the respirator and being fit tested.

User Seal Checks

The individual who uses a tight-fitting respirator is to perform a user seal check to ensure that an adequate seal is achieved each time the respirator is put on. Either the positive and negative pressure checks listed below, or the respirator manufacturer's recommended user seal check method shall be used. User seal checks, however, are not substitutes for qualitative or quantitative fit tests.

Facepiece Positive and/or Negative Pressure Checks

Positive pressure check. Close off the exhalation valve and exhale gently into the facepiece. The face fit is considered satisfactory if a slight positive pressure can be built up inside the facepiece without any evidence of outward leakage of air at the seal. For most respirators this method of leak testing requires the wearer to first remove the exhalation valve cover before closing off the exhalation valve and then carefully replacing it after the test.

Negative pressure check. Close off the inlet opening of the canister or cartridge(s) by covering with the palm of the hand(s) or by replacing the filter seal(s), inhale gently so that the facepiece collapses slightly, and hold the breath for ten seconds. The design of the inlet opening of some cartridges cannot be effectively covered with the palm of the hand. The test can be performed by covering the inlet opening of the cartridge with a thin latex or nitrile glove. If the facepiece remains in its slightly collapsed condition and no inward leakage of air is detected, the tightness of the respirator is considered satisfactory.

Manufacturer's Recommended User Seal Check Procedures

The respirator manufacturer's recommended procedures for performing a user seal check may be used instead of the positive and/or negative pressure check procedures provided that the employer demonstrates that the manufacturer's procedures are equally effective.