OSHA requirements are set by statute, standards and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. This letter constitutes OSHA's interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at https://www.osha.gov.

This memorandum provides specific enforcement policy for respiratory protection required in abrasive-blasting operations under the Interim Final Rule for Lead in Construction, 29 CFR 1926.62 (hereafter called the "Lead in Construction Standard"). Three points are especially important in this regard. First, the change only applies to 29 CFR 1926.62. Second, the change only affects enforcement actions involving the Type-CE respirator used in abrasive-blasting that is manufactured by 3M as the Model 8100 Abrasive Blast Helmet. Third, the change is an interim one, pending a final determination by the Occupational Safety and Health Administration (OSHA) of the proper protection factor to be assigned to this class of respirators consequent to a forthcoming rulemaking on assigned protection factors (APF). Pending that determination, Regional Administrators shall ensure that the following policy is implemented. State designees are encouraged to adopt a similar enforcement policy for respiratory protection under 29 CFR 1926.62.

Based upon the 1987 Respirator Decision Logic developed by the National Institute of Occupational Safety and Health (NIOSH), OSHA in the Lead in Construction Standard designated an APF of 25 times the permissible exposure (PEL) for all Type-CE, continuous-flow, loose-fitting, atmosphere-supplying, airline abrasive-blast respirators (hood or helmet). With that assigned protection factor, this type of respirator would be acceptable for use only where airborne lead concentrations are less than or equal to 25 times the PEL of 50 ug/m(3), which is 1250 ug/m(3).

In a August 7, 1998, letter to OSHA, 3M Occupational Health and Safety Division provided documentation showing that their continuous flow Model 8100 Abrasive Blast Helmet achieved a considerably higher protection factor than the APF of 25 as currently assigned. 3M maintained that its respirator provides much greater protection and sought to have the APF under the Lead in Construction Standard (29 CFR 1926.62) elevated to 1000.

3M contracted with an acceptable independent third party to design, monitor, and interpret the results of a simulated workplace study of the Model 8100 under a test protocol that had been approved by OSHA. As a condition for granting relief, the Agency required that the results of the study demonstrate that the abrasive-blast respirator achieve, at a minimum, a protection factor rating of at least 20,000, and maintain positive pressure throughout the testing.

3M contracted with Los Alamos National Laboratory which designed, conducted, and interpreted the results of a study based on the OSHA-approved protocol. In the test, the Model 8100 respirator achieved a minimum protection factor of greater than 20,000, and maintained positive pressure throughout the testing.

OSHA recognizes that a protection factor greater than 25 is appropriate for the 3M Abrasive Blast Helmet, Model 8100. The simulated workplace study carried out by the Los Alamos National Laboratory indicates that, if used properly, this respirator is acceptable for exposures to lead that are less than or equal to 1000 times the PEL (50,000 ug/m(3)). However, other data, and at least one field study, indicate that in the workplace these respirators may provide considerably less protection than indicated by the simulation study. Protection is degraded when the respirators are used in ways that do not conform to the manufacturer's specifications (e.g., the air supply hose is too long, the hose diameter is incorrect and/or the manufacturer's specified pressure is not maintained), or in ways that do not comply with the requirements of 29 CFR 1910.134 (e.g., the respirator is not inspected frequently enough for possible deterioration), which are incorporated by reference in the Lead in Construction Standard, 29 CFR 1926.62(f)(4).

Respirators will provide less protection than their design capability when used improperly. Examples of improper respirator use include the donning and doffing of respirators while employees are still in containment, or if they disconnect the air hose prior to leaving the exposure area. What is unusual in connection with these respirators is the extreme conditions under which they may be used in construction activities. Typically, abrasive blast respirators are used at very high levels of exposure and are subject to substantial and, at times, rapid deterioration due to damage caused by the high-speed, abrasive material used in the blasting. Also, at times, these respirators will sometimes be used near the limits of their protective capability. Consequently, workers using these respirators in abrasive- blasting operations may be subject to acute toxic exposures if the respirators do not perform properly. It is imperative, therefore, that these respirators be properly used.

For these reasons, OSHA will adopt the following approach in its enforcement policy with regard to these respirators:

First, this 3M model will be treated by OSHA as if it had an APF of 1000. Effective immediately for abrasive-blasting operations covered under the Interim Final Rule for Lead in Construction, the 3M Model 8100 Abrasive Blast Respirator is acceptable in abrasive-blasting atmospheres where the airborne level does not exceed 50,000 ug/m(3) (1000 times the PEL) of lead n air.

Second, OSHA will be very strict in assuring that this respirator is used only in accordance with the requirements of 29 CFR 1926.62. During compliance activities, CSHO's shall determine that all 3M respirators consist of the appropriate components, such as correctly sized air supply hoses and hose length, and that the required pressure range is maintained. If the respirator is not used in compliance with the manufacturer's specifications and with 29 CFR 1926.62, CSHO's will document the respiratory deficiencies. Violations related to documented deficiencies in the respirator will be cited.

Third, relief for this model applies only to lead in construction. The APF of 1000 does not apply to other air contaminants.

OSHA is now reviewing literature and comments for assigned protection factors for the inclusion in the revised respiratory protection standard 29 CFR 1910.134. OSHA will determine if an APF of 1000 should be assigned to the class of respirators addressed in this memorandum. The relief being granted to 3M, therefore, is interim relief only. Decisions in OSHA's final revised Respiratory Protection rule will supersede this decision and may reflect an APF different than 1000.

If you should have any further questions concerning this matter, please feel free to contact the Office of Health Compliance Assistance at (202) 693-2190.