NIOSH recommends that air sampling be conducted to determine exposure levels found in the workplace. A combination of air sampling and exposure modeling is often used to make reasonable estimates of exposure. Ideally, this determination should be made by a professional industrial hygienist. Also, OSHA offers free consultation to qualifying small- and medium-sized businesses to help recognize hazards, suggest approaches to solving problems and identifying the kinds of help available if further assistance is required.

Obtaining complete information on all criteria needed to use this selection logic may be difficult. When conflicting or inadequate data are found, experts should be consulted before decisions are made that could affect the proper use of this selection logic. In addition, the adequacy of the respirator selected is dependent on the validity of the exposure limit used and the accuracy of the hazard concentration determination.

While the selection logic can be used with any exposure limit, NIOSH recommends that the more protective limit of the NIOSH REL or the OSHA PEL, be used in respirator selection. If no REL or PEL exists, other applicable occupational exposure limits such as the ACGIH TLV can be used.

The information obtained on general use conditions for respirators should include a description of the actual job task, including the duration and frequency, location, physical demands, and industrial processes, as well as issues affecting the comfort of the respirators. Some conditions may preclude the use of specific types of respirators in certain circumstances because the individual must be medically and psychologically suited (i.e., not claustrophobic) to wear a given respirator for a given task, particularly if the respirator is a self-contained breathing apparatus (SCBA).

Employers must establish a cartridge/canister change-out schedule based on the service life of the cartridge/canister under the conditions of use. The change-out schedule can be determined with the assistance of the respirator manufacturer (change-out software or other tools) or by conducting service life tests. Information obtained on the service life of the cartridge/canister under conditions of intended use must be evaluated regardless of the odor warning properties of the chemicals.

These evaluations must be based on all gases and vapors present at the temperature and relative humidity extremes (high and low) in the workplace. NIOSH recommends that when the employer or a representative of the employer conducts service life tests, the challenge concentrations of the gases and vapors should be at least the maximum use concentration (MUC) of the respirator and that a safety margin be applied when evaluating service life data.

In humid workplaces where organic vapor cartridges are used to protect workers from a single volatile source, software for predicting service life can be ordered from NIOSH by calling 1-800-356-4674. The software can also be downloaded from the OSHA web site. This information can be used to set up cartridge replacement schedules and should be used in conjunction with sensory warning properties.

Although odor should not be relied on for cartridge/canister change out, workers should be trained to exit the contaminated area whenever they detect the odor or experience any irritation symptoms of the contaminant.

If workers are detecting the odor before the end of the change schedule, the respirator program administrator should reevaluate this respirator use; i.e., the change schedule, the workplace concentrations or the other use conditions (relative humidity (RH), work rate, etc.).

The following requirements and restrictions must be considered to ensure that the respirator selected will provide adequate protection under the conditions of intended use:

1. Workers are not exposed to a single unvarying concentration of a hazardous substance, rather, individual exposures may vary throughout a work shift and between days. The highest anticipated concentration should therefore be used to compute the required protection factor for each respirator wearer.

2. Qualitative or quantitative fit tests must be provided as appropriate to ensure that the tight-fitting facepiece respirator fits the individual. NIOSH endorses the OSHA standard 29 CFR1910.134 for fit testing except for irritant smoke.

Employees must pass a fit test with the exact model and size that they will wear in the workplace.

3. Respirators with tight-fitting facepieces should not be used when facial scars or deformities interfere with the face seal.

4. Respirators with tight-fitting facepieces (including pressure-demand respirators) should not be used when facial hair interferes with the face seal.

5. The usage limitations of air-purifying elements, particularly gas and vapor cartridges or canisters, should not be exceeded (see NIOSH Certified Equipment List for general limitations at www.cdc.gov/niosh/npptl/topics/respirators/cel).

6. Respirators must be certified by NIOSH. A list of certified respirators can be found at www.cdc.gov/niosh/npptl/topics/respirators/cel/.

7. A complete written respiratory protection program must be developed which includes regular worker training; maintenance, inspection, cleaning, and evaluation of the respirator; use of the respirator in accordance with the manufacturer’s instructions; fit testing; medical evaluation; and environmental monitoring. Minimum respiratory protection requirements for some contaminants can be found in the OSHA Respiration Protection Standards, 29 CFR 1910.134.

Detailed information on respirator programs can be accessed at: www.osha.gov/SLTC/etools/respiratory. In addition, the OSHA Small Entity Compliance Guide provides procedures and checklists that can help small businesses comply with the respirator standard. This information can be accessed at www.osha.gov/Publications/SECG_RPS/secgrev-current.pdf.

In order to provide protection, the respirators must be used in a complete respirator program such as the one required by OSHA in 29CFR1910.134. FSM