Health hazard evaluation report: HETA-2006-0156-3031, Harley-Davidson Motor Company, York, Pennsylvania.
In February 2006, workers at the Harley-Davidson Motor Company plant in York, Pennsylvania, requested a NIOSH health hazard evaluation (HHE) regarding welding-related exposures in Building 4 (frame shop). The workers were concerned that the ventilation system was not adequately controlling exposures to welding fume. They reported that recent company air sampling indicated that their exposures were too high. They were not aware of any workers with respiratory problems; one of two workers interviewed reported a history of "cramping up" in his/her hands and feet and a decreased sense of smell. The workers also reported that part of the fume collection system had caught on fire in January and February 2006, requiring part of the ventilation system to be shut off for maintenance and repair. Workers reported that during one of these events, several welders were allowed to keep welding for several minutes after the local exhaust ventilation to their work area had been shut off. A NIOSH team visited the plant on May 3, 2006, to perform a walkthrough of Building 4 and to obtain additional information on exposures, controls, and worker health concerns. The company reported that it follows the 2006 American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value (TLV®) for manganese (Mn) of 0.2 mg/m3 as its exposure limit. Of the 17 Mn exposure measurements made by the company in January and February 2006, three exceeded the TLV®; the highest Mn exposure was 0.32 mg/m3. The company reported that it follows the ACGIH TLV® of 5 mg/m3 for welding fume. (As of 2004, ACGIH no longer has a TLV® for welding fume.) Of the 15 welding fume exposure measurements made by the company in January and February 2006 (99% iron oxide according to management), 12 were below 5 mg/m3. The results for the other three measurements were 5.1 mg/m3, 5.8 mg/m3, and 7.9 mg/m3. The OSHA PEL for iron oxide is 10 mg/m3 TWA. The ACGIH TLV® and NIOSH REL for iron oxide are 5 mg/m3 TWA. Currently OSHA does not have a specific PEL for welding fume. NIOSH recommends that exposures to welding fume contaminants be reduced to the lowest concentrations technically feasible. During the site visit, no workers requested to speak privately with NIOSH staff regarding health or exposure concerns. The company reported that the most likely cause of the recent fires in the one of the fume collection units was that burning debris entered through a local exhaust duct, or a welding spark ignited particulate buildup in the ducts, ultimately leading to a fire in a filter in one of the modules of one fume collection unit. After the February 2006 fire, the exhaust ventilation ducts and hoods were cleaned out. An outside consultant hired by the company to perform a survey of the fume collection units and ventilation systems recommended several repairs and improvements. One of the consultant's recommendations was to install pressure gauges for each filter module in the fume collection units in order to detect excessive particulate accumulation on filters that could increase the likelihood of fire. The consultant also identified several local exhaust ventilation locations where air flow was insufficient. The company reported that it planned to rebalance the ventilation systems, install an additional fume collection unit and additional local exhaust ventilation hoods, and install pressure gauges for each fume collection unit filter module by the end of 2006. Management should repeat air sampling for welding-related exposures after all ventilation interventions have been completed. Work areas with exposures that are above (or only slightly below) applicable exposure limits should be reassessed to identify possible ways to further decrease exposures. Because of the potential for decreased lung function, lung cancer, and neurologic disease (from chronic manganese exposure), company management should aim to reduce welding-related exposures to the lowest concentrations technically feasible. While only one worker in Building 4 reported any symptoms, decreased lung function and neurologic disease can have a gradual onset and may not be recognized early on. These diseases are often not reversible or treatable. Therefore, it is important to limit exposures that could lead to these conditions. It is also important that welders understand the potential health risks of welding-related exposures and how they can decrease their exposure through optimal use of controls and work practices.