Respiratory protection: airborne contaminants

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. 

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. 

IDLH Immediately Dangerous to Life or Health levels indicate that exposure to the listed concentrations of airborne contaminants is likely to cause death, immediate or delayed permanent adverse health effects, or prevent escape from the contaminated environment. IDLH levels are established to ensure that the worker can escape from the contaminated environment in the event of a failure of respiratory protection. An indication of "10% LEL" indicates that, for safety considerations, the IDLH was based on an atmospheric concentration of ten percent of the lower explosive limit even though toxicological impacts might not appear until higher concentrations are reached. 

NFPA 471 Chapter 7, has additional details on personal protective equipment requirements including four levels protection A - when highest level of respiratory, skin, and eye protection is required B - when the highest respiratory protection is reqrrired, but lesser skin protection is needed C - when the concentration of airborne contaminants is known and air pmifying respirators are reqrrired D - when only nuisance contamination exists. Note There are nttmerous other NFPA reqrrirements for PPE, many of which are cited in NFPA 471, Chapter 7. 

Iffora valid reason, full control of the levels of airborne contaminants cannot be maintained within the legal limits, it is permissible to userespiratory protectionundersome conditions. These are found in the current Part 20, Subpart H in Section 20.1703 and in Appendix A to Part 20. A key provision in 20.1703(a)(3) is for the licensee to have a formal written respiratory protection program. 

Employee exposure means exposure to a concentration ofan airborne contaminant that would occur if the employee were not using respiratory protection. 

Respiratory protection Devices that will protect the wearer s respiratory system from overexposure by inhalation to airborne contaminants. Respiratory protection is used when a worker must work in an area where he/she might be exposed to concentration in excess of the allowable exposure limit. 

Whenever respirators are used, their use must comply with 1926.103 — Respiratory protection. Various airborne contaminants in Appendix A of 1926.55 do not list PELs but instead send you to another portion of the construction regulations. These contaminants are called OSHA specific contaminants. Examples are Asbestos ( 1926.1101), alpha-Naphthylamine ( 1926.1104), and lead ( 1926.62). There are approximately 27 of these substances. These OSHA specific contaminants have their own PELs and specific requirements. When you are required to use respirators in construction, then all requirements of 29 CFR 1910.134 for general industry apply. 

Some common types of personal protection equipment are eye and face protection for hazardous liquids and respiratory protection for airborne contaminants. Protection for some hazardous materials may involve other clothing, protective creams and lotions for skin. Infrequent activities, such as maintenance or spill cleanup tasks, may require full suits and air supply equipment. 

In addition, depending on the type of chemicals and type of exposure, the respiratory tract should also be protected against inhalation of airborne contaminants, which can be in the form of particles, vapors or gases. Also, hearing protectors should not be forgotten. The need to use hearing protectors starts when the noise level, in spite of engineering control measures, exceeds the national limit value, which is 90 or 85 dB in many countries (Korhonen 1997). 

All these safety measures must be taken in addition to the standard protective measures deployed in any chemical laboratory lab coats or overalls, gloves and footwear, eye and face protection and respiratory protection. Contamination of surfaces must be avoided and control of airborne contaminants must be practiced (Perkin-EImer n.d.). 

The Occupational Safety and Health Act (OSH Act) requires that every employer provide a safe and healthful work environment. This includes ensuring that workers are protected from unacceptable levels of airborne hazards. Although most air is safe to breathe, certain work operations and locations have characteristic problems of air contamination. Control measures are required to reduce airborne hazard concentrations to safe levels. When controls are not feasible or while they are being implemented, workers must wear approved respiratory protection. 

Respiratory protection—a standard or program designed to protect employees from airborne contaminants. 

For the purposes of radiation protection, the primary objective of providing a ventilation system should be to control the contamination of the working environment by airborne radionuclides and to reduce the need to wear respiratory protection. 

In areas where airborne contamination or loose surface contamination is present or may be produced during work, use of respiratory protective equipment may be necessary and should be considered. The protective equipment should meet the specifications in the RWP and any administrative procedures should be complied with. 

Respiratory protective equipment (RPE) should be worn where there is an unavoidable risk of exposure to harmful airborne contamination, or a shortage of oxygen is likely to be encountered. Breathing apparatus fed with compressed air, or self-contained breathing apparatus (open and closed circuit) to BS 4667, must be used in oxygen-deficient atmospheres, though special training is required for their use. In certain circumstances RPE may be the preferred method of protection and it is commonly used ... 

A beard may be undesirable in the laboratory if there is airborne contamination because a beard retains particulate contamination more persistently than clean-shaven skin. Also, a clean-shaven face is essential to the adequate facial fit of a face mask or respirator when the work requires respiratory protection... 

On arrival, all medical staff should identily the officer in charge of the incident— the incident commander (this will usually be a senior fire or police officer), the incident command centre if it is already set up. The presence of each worker and any special skills, equipment or knowledge that they have can then be logged. Preparation should be made for the use of PPE at this time (see Chap. 4). Respiratory protection is the most important aspect of this and respirators should be kept close by to allow rapid domiing if the situation deteriorates and there is immediate airborne contamination (e.g. from a change in wind direction). 

Respiratory protection Devices that will protect the wearer s respiratory system from overexposure by inhalation to airborne contaminants. 

Industrial environments expose individuals to a plethora of airborne chemical compounds in the form of vapors, aerosols, or biphasic mixtures of both. These atmospheric contaminants primarily interface with two body surfaces the respiratory tract and the skin. Between these two routes of systemic exposure to airborne chemicals (inhalation and transdermal absorption) the respiratory tract has the larger surface area and a much greater percentage of this surface exposed to the ambient environment. Or dinary work clothing generally restricts skin exposures to the arms, neck, and head, and special protective clothing ensembles further limit or totally eliminate skin exposures, but breathing exposes much of the airway to contaminants. 

Epidemiological and Human Dosimetry Studies. Results from many acute controlled-exposure human studies and cross-sectional studies of groups of persons repeatedly exposed to airborne formaldehyde provide strong evidence that the upper respiratory tract is the critical target of airborne formaldehyde for any duration of exposure, allow reasonable estimates to be made of minimal risk levels for acute and chronic durations of exposure, and provide strong support for deriving intermediate-duration minimal risk levels from animal exposure-response data. There is considerable confidence that adherence to these values will protect persons living near formaldehyde-contaminated hazardous waste... 

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