Respiratory protection selection, respirator

Personnel protective equipment may be used in certain circumstances where exposure to airborne particulates contaminated with chemical carcinogens could occur. In those situations, personnel should be equipped with a complete clothing change, as well as respiratory protection selected on the basis of work performed, type of chemical used, and containment equipment. The respiratory protection may be a face mask, respirator [selected from those approved by the National Institute for Occupational Safety and Health (NIOSH)] (4, 5), or emergency breathing air system. In the latter case, a head hood or a complete protective suit may be used with a breathing air supply system. Figure 2. 

Level C protection should be selected when the type of airborne substance(s) is known, concentration is measured, criteria for using air-purifying respirators are met, and skin and eye exposure are unlikely. It involves a full face piece, air-purifying, canister-equipped respirator and chemical-resistant clothing. This level of protection provides the same degree of skin protection as Level B, but a lower level of respiratory protection. 

The immediately dangerous to life or health (IDLH) air concentration values have been recommended by the US National Institute for Occupational Safety and Health (NIOSH) as respirator selection criteria. The current NIOSH definition for an IDLH condition is a situation that poses a threat of exposure to airborne contaminants when that exposure is likely to cause death or immediate or delayed permanent adverse health effects or prevent escape from such an environment. NIOSH s stated purpose for establishing IDLH values is to ensure that the worker can escape from a given contaminated environment in the event of failure of the respiratory protection equipment. The complete introduction and documentations to the 398 existing IDLH values can be read or downloaded at the NIOSH Internet website. 

Respiratory protection including selection of respirators on the basis of exposure to VCM concentrations from less than 10 ppm to above 3600 ppm, and establishment and maintenance of a respiratory protection program,... 

The type and atmospheric concentration of toxic substances has been identified and requires a high level of respiratory protection, but less skin protection than Level A. Typically, these would be atmospheres with IDLH concentrations, but the substance or its concentration does not represent a severe skin hazard or the atmosphere does not meet the selection criteria permitting the use of air-purifying respirators. 

A study, conducted in the workplace, that measures the protection provided by a properly selected, fit-tested, and functioning respirator when used intermittently for only some fraction of the total workplace exposure time (i.e., sampling is conducted during periods when respirators are worn and not worn). EPFs are not directly comparable to Workplace Protection Factor (WPF) values because the determinations include the time spent in contaminated atmospheres both with and without respiratory protection therefore, EPFs usually underestimate the protection afforded by a respirator that is used continuously in the workplace. See also Protection Factor Stndy Workplace Protection Factor (WPF) Study. 

A study, conducted under actual conditions of use in the workplace, that measures the protection provided by a properly selected, fit-tested, and functioning respirator, when the respirator is worn correctly and used as part of a comprehensive respirator program that is in compliance with the Occupational Safety and Health Administration (OSHA) Respiratory Protection Standard 29 CFR 1910.134. Measurements of Co and Ci are obtained only while the respirator is being worn during performance of normal work tasks (i.e., samples are not collected when the respirator is not being worn). As the degree of protection afforded by the respirator increases, the WPF increases. 

Respirators prevent the inhalation of harmful airborne substances and provide fresh air in oxygen-deficient environments. An effective respiratory protection plan must address the following (1) hazards encountered, (2) type and degree of protection needed, (3) medical evaluation for respirator usage, (4) selection and fit requirements, (5) training on use and care, and (6) methods to ensure continued effectiveness. 

Respirators are a last resort for controlling a hazard and preventing exposure. They should not be used unless all other methods of control are inadequate. Respirators should be properly selected, should be correctly fitted to a person s face, and a person using a respirator should be aware of its uses and limitations. It is essential that all respirator users receive training in respiratory protection and that respirator users must work in teams of at least two workers. ... 

Selecting respiratory protective equipment for use in the workplace has been the topic of several well-known references (NIOSH, 1985 OE, 1991 CSA, 1993). Some publications have dealt with selecting respirators for spill situations (EPA, 1992 Fingas, 1996). The differences between selecting a respirator for the workplace and selecting a respirator for use in spill situations hinge on the certainty with which both the substances present and their concentration are known. In spill situations, maximum protection must often be used because of the possible presence of high concentrations of chemicals. 

Protection factors are important criteria for selecting respiratory protective equipment. The protection factor must be sufficiently high to reduce the contaminant inside the facepiece to an acceptable level, usually taken as the TLV, or threshold limit value. The Appendix lists the TLV values for commonly spilled materials. These data are used in the following manner (ACGIH, 1999 NIOSH, 1994). A spill of a substance with a TLV of 5 ppm, which according to calculations could rise as high as 5,000 ppm, would require a respirator with a protection factor of at least 1,000. For a safety factor of 2, a protection factor of 2,000 would be required. Pressure-demand SCBAs, which have a protection factor of about 10,000, represent the ultimate in safety and are generally used at spill scenes because the exact substance and the level of the contaminants are not known for certain until measurements have been made. 

The selection process for a respirator is shown in Fig. 30.1. The following guidelines can simplify the selection process for respiratory protective devices for use at a spill scene. 

Your employer must also start a Respiratory Protection Program. This program must include written procedures for the proper selection, use, cleaning, storage, and maintenance of respirators. 

In addition to respirator selection, a complete written respiratory protection program should be instituted which includes regular training, maintenance, inspection, cleaning, and evaluation. If you can smell MC while wearing a respirator, proceed immediately to fresh air. If you experience difficulty in breathing while wearing a respirator, tell your employer. 

Because each worker s environment is different, and the amount of occupational exposure to crystalline silica dust varies, an occupational exposure determination should be completed before selecting an appropriate respirator. The minimum respiratory protection for a worker who is working with crystalline silica dust, but is not doing abrasive-blasting, may be an N95 NIOSH-approved respirator. However, the exposure to crystalline silica must not exceed the assigned protection factor of the respirator. 

Where asbestos is the only hazardous substance present, you may follow the specifications in the asbestos standards with regard to PPE selection. If the airborne concentration of asbestos fibers is unknown, then fuii facepiece, supplied-air respirators operated in pressure demand mode and equipped with auxiiiary positive pressure self-contained breathing apparatus must be used ( 1926.1101 (h)(3)(i)). This level of PPE is required until appropriate air monitoring results indicate that a lesser level of respiratory protection is adequate. 

Mar f items of PPE are the subject of testing to an accepted national or international standard. In addition, flow charts within some standards assist in selecting the specific type of a particular category of PPE, e.g. choice of self-contained breathing apparatus, positive pressure air-supplied respirator, powered air purifying respirator, or passive respirator (and which type of cartridge or canister), if respiratory protection is being sourced. 

Comfort of the facepiece is also important. If the face-piece does not fit comfortably, the user may resist wearing respiratory protection, may become distracted and less attentive on the job, or may need to take additional breaks to find relief fiom the discomfort. The respirator fit test should always include a comfort assessment, especially when evaluating a facepiece the user has not worn in the past When performing the comfort assessment, consider the use of other personal protective equipment (PPE) such as safety glasses to ensure these can be worn properly and effectively with the selected facepiece. 

All personnel entering areas where chlorine is stored or handled should carry or have immediately available an escape-type respirator. Respiratory equipment should be selected based on evaluation of hazards and degree of potential exposure. For example, when tank cars, ton containers or cylinders are connected to or disconnected from plant piping, small releases of chlorine can occur. The need for respiratory protection during such operations should be determined. 

Within these classes there are many different sub-classes of RPE and it is important to choose the correct type of equipment based on a risk assessment. A British Standard gives guidance on the selection, use and maintenance of respiratory protective equipment. From the risk assessment, it is necessary to decide whether to use a respirator or breathing apparatus. The minimum protection required for the situation then needs to be considered ... 

The NIOSH-OSHA Standards Completion Program — Respirator Decision Logic provides guidance of the limitations of the equipment and OSHA compliance. In selecting the proper respiratory protection device, the physiology of the wearer, the toxicity of the hazards encountered by leakage or misuse and the hazard of sampling all must be considered carefully. 

The purpose of the Respirator Decision Logic is to assure technical accuracy and uniformity between substances in the selection of respirators and to provide necessary criteria to support this selection. The decision logic is a step-by-step elimination of inappropriate respirators until only those that are acceptable remain. Judgment by persons knowledgeable of inhalation hazards and respiratory protection equipment is essential to ensure appropriate selection of respirators. 

---