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OSHA comments from the January 19, 1989 Final Rule on Air Contaminants Project extracted from 54FR2332 et. seq. This rule was remanded by the U.S. Circuit Court of Appeals and the limits are not currently in force.

CAS: 7429-90-5; Chemical Formula: Al

OSHA formerly had no permissible exposure limit for aluminum welding fumes. The proposed PEL was 5 mg/m3, which is consistent with the ACGIH limit. The final rule promulgates an 8-hour TWA for aluminum welding fumes of 5 mg/m3, measured as aluminum. NIOSH (Ex. 8-47, Table N1) concurs with this limit.

OSHA received two comments pertaining to aluminum welding fumes. The first commenter (Ex. L3-1330) sought clarification as to whether the term “aluminum welding fumes” refers to aluminum fumes or to the gases and fumes usually associated with aluminum welding, such as ozone, nitrous gases, carbon monoxide, and carbon dioxide. The second commenter, the Specialty Steel Industry of the United States (Ex. 3-829), objected to the establishment of a permissible exposure limit for aluminum welding fumes because, in this commenter’s opinion, no scientific evidence was cited in the proposal to indicate that exposure resulted in deleterious effects (Ex. 3-829, p. 6).

The PEL addresses the aluminum fume that is released in the welding process; this limit is being established to keep the total aluminum particulate concentrations low enough to prevent aluminum particle accumulation in the lungs. However, to the extent either that other toxic substances or materials are released in the welding process or that conditions are conducive to the formation of toxic gases, employers must pay attention to the permissible exposure limits for these substances as well. For example, in Appendix B of the 1987-88 Threshold Limit Values and Biological Exposure Indices (ACGIH 1987/Ex. 1-16), the ACGIH states that “reactive metals and alloys such as aluminum and titanium are arc-welded in a protective, inert atmosphere such as argon. These arcs create relatively little fume, but an intense radiation which can produce ozone” (ACGIH 1987/Ex. 1-16, Appendix B, p. 42). In such an instance, employers would be required to meet the ozone limits established in this rulemaking (0.1 ppm TWA and 0.3 ppm STEL) as well as the PEL for aluminum welding fumes.

The ACGIH states that “most welding, even with primitive ventilation, does not produce exposures inside the welding helmet above 5 mg/m3. That which does…should be controlled” (ACGIH 1987/Ex. 1-16, Appendix B, p. 43). In those rare instances where internal helmet exposures do exceed 5 mg/m3, employees are at risk from the irritant effects of hot metal fumes, which enter the lung deeply and accumulate.

Because workers exposed to arc welding fumes have previously not been protected by a permissible exposure limit, OSHA is establishing a PEL of 5 mg/m3 TWA for these fumes, (measured in the breathing zone of the welder; the details of the appropriate positioning of the sampler should be determined on the basis of guidance in the Field Operations Manual (OSHA 1984). This is consistent with a past OSH Review Commission decision (8 OSHRC 1049). The Agency concludes that this limit will protect welders and other workers in the vicinity of the welding from experiencing the significant irritation potentially associated with inhalation of these fumes; OSHA finds the respiratory irritation caused by exposure to these fumes constitutes a material health impairment.