The criteria for selection should be clearly stated in the respiratory protection program. For nickel and nickel compounds, these should include such factors as the possible concentration of the contaminants present, the particle size(s) encountered, the toxicity of the chemicals, and the limitations of the respirators. The concentration of the contaminant will dictate whether a half-face, air purifying respirator is appropriate, or whether a higher level of protection, such as that provided by a supplied air respirator, is required. Once the employer has established that the hazardous conditions do not include oxygen deficiency, toxic gases, or atmospheres otherwise immediately dangerous to life and health, a determination of the protection needed should be calculated. The minimum protection factor needed is the ratio of the exposure concentration to the exposure limit. Any respirator tested should have a rated protection factor at least as large as this ratio (Table 8-1). Quantitative fit testing is required to ensure that the respirator performs as desired.
Nickel and its compounds will generally be in particulate form such as dusts (solid particulate), mists (liquid condensation particulate), and fume (solid condensation particulate, usually as oxidized forms of nickel). Filters appropriate to each form are available as single-use respirators or in canisters and cartridges that attach directly to molded facepieces. In the case of powered, air- purifying respirators, the canisters are attached to the facepiece with a hose. The fit of a respirator with a molded facepiece is more readily determined than is the fit of a single-use respirator, but the latter is generally more comfortable.
High concentrations of the nickel compound may require the use of supplied air by either an airline or battery powered respirator or a self- contained breathing apparatus (SCBA). Airline respirators and battery powered respirators provide a continuous supply of air for long durations. The SCBAs, on the other hand, have a limited air supply (from 30 minutes to 4 hours) but allow for a greater degree of mobility and, because of the positive pressure, have a higher protection factor. Use of a SCBA requires significant training and a health assessment of the worker.
- Half- and full-face, air-purifying, any type of particulate filter
- Half-face, supplied air, demand mode
- Powered air-purifying, hood or helmet, any type of particulate filter
- Supplied air, hood or helmet, continuous flow mode
- Full-face, air purifying, HEPA filters
- Powered air-purifying, tight facepiece, HEPA filters
- Supplied air, full-face, demand mode
- Supplied air, tight-facepiece, continuous flow mode
- SCBA, full-face, demand mode
- Supplied air, half-face, pressure demand or positive pressure mode
- Supplied air, full-face, pressure demand or positive pressure mode
- Supplied air, full-face, pressure demand or positive pressure mode with an auxiliary SCBA, pressure demand or positive pressure mode
- SCBA, full-face, pressure demand or positive pressure mode
Source: National Institute for Occupational Safety and Health (1987)
When selecting air purifying respirators, employers should consider assigning each employee his/ her own respirator. Care and maintenance, thus, become a matter of personal importance, and the responsibility for the health of a worker is shared between employer and employee. Each employee should ensure that the respirator issued fits properly and hence provides the intended degree of protection. In some jurisdictions, respirator fit-testing is mandatory.