Respirator decisions

What factors will help me determine the correct respirator needed for a specific job?

Responding is Jeffrey Birkner, vice president – technical services and quality assurance for Moldex-Metric Inc., Culver City, CA.

Various items need to be considered when choosing the appropriate respirator. If the exposure level is less than 10 times the exposure limit, usually some type of half-mask respirator can be chosen. Instances in which this may not be true include areas in which the contaminant is unknown, the atmosphere is immediately dangerous to life or health, a substance-specific standard specifies otherwise, or some other factor dictates a higher level of protection. The proper choice should be made with the help of a qualified health and safety professional, such as an industrial hygienist.

NIOSH is the regulatory agency that governs the certification and manufacture of respirators. NIOSH certifies three series: N, R and P with three levels of filter efficiency – 95 percent, 99 percent and 100 percent (actually 99.97 percent). Once a product has been approved by NIOSH, it receives a TC number that shows it is certified. Assuming that a half-mask respirator is found to be acceptable, and if the substance is a dust or non-oil-based particulate (including welding fumes), any type of respirator with an N, R or P series filter is appropriate.

If the substance is an oil-based mist, an R or P filter should be considered. The level of protection (95 percent, 99 percent or 100 percent) will depend on the toxicity of the substance. Highly toxic substances such as arsenic, lead and cadmium require a 100-level filter. Whether the respirator is disposable or reusable usually is more a matter of preference than a requirement, except in specific-use situations such as asbestos. When the contaminant is a chemical gas or vapor, your choice will be an elastomeric facepiece with the appropriate cartridge. If dusts or mists also are present, you will want to add a pre-filter for the cartridge. Again, you will need to make your choice with the help of a safety professional.

Always check each manufacturer’s instructions and warnings before using a respirator.

Editor's note: This article represents the independent views of the author and should not be construed as a National Safety Council endorsement.