On November 15, 2005, the National Institute for Occupational Safety and Health (NIOSH) received a request for a Health Hazard Evaluation from workers at DaimlerChrysler's Jefferson North Assembly Plant (JNAP) in Detroit, Michigan. The request stated that workers were experiencing respiratory problems (asthma, chronic bronchitis, chronic obstructive pulmonary disease (COPD)) and deaths in the setting of inadequate control of welding-related exposures. Several workers reported that they were aware of coworkers who had developed respiratory disease (COPD, cancer) after they started working at the plant and had died at relatively young ages (mid 40s to early 60s). A young worker with preexisting asthma had died of asthma in October 2005 several hours after getting off work. Findings indicating that asthma was the cause of death were noted on the autopsy report. Most of the welding at JNAP is resistance (spot) welding performed by robots. Some of the welding areas have plastic sheeting and exhaust fans (process ventilation) to decrease contamination of the plant air. Some repair welding is performed by workers utilizing gas metal arc welding (also known as metal inert gas (MIG) welding) and flux-cored arc welding. Among the concerns reported by workers was the potential for increased welding-related exposures when less outside air is brought into the plant by the ventilation system during cold weather. Workers reported that repair welding was often performed with no local exhaust ventilation. Workers were also concerned about the potential for health effects from exposures to chemicals resulting from welding on metal parts that have had adhesives applied in the production process. Some workers on the fluid-fill deck reported recurrent problems with asthma, bronchitis, and sinusitis that they felt were related to exposures to engine fluids (radiator, brake, power steering) and airconditioning refrigerant. NIOSH staff visited JNAP from February 8-10, 2006 to obtain additional information regarding potential worker exposures and health effects. NIOSH staff performed a walkthrough of the entire facility and performed qualitative and semiquantitative air sampling for particulate and volatile organic compounds (VOCs) at several locations. The highest particle counts were for particles less than one micrometer in diameter. Some of the VOCs detected in the plant air were also detected in the headspace of adhesive bulk samples. NIOSH staff reviewed air sampling data and material safety data sheets provided by the company, and two reports prepared by the Michigan Occupational Safety and Health Administration (MIOSHA) which detailed the findings of their evaluations of welding-related exposures at JNAP in October 2005 and January 2006. None of the air sampling results exceeded existing MIOSHA permissible exposure limits or NIOSH recommended exposure limits. The potential for eye, skin, or respiratory tract irritation from exposures to adhesives and other substances used in the plant was documented in material safety data sheets. Twenty one employees discussed their health concerns with NIOSH staff. Four of these employees permitted review of their medical records. Information on the 31 year-old employee, who died after completing his work shift, was obtained from an autopsy report, his next of kin, and coworkers. Seven employees in the body shop reported symptoms consistent with new-onset asthma or exacerbation of pre-existing asthma (including the 31 year-old employee who died after completing his work shift). Three of these seven employees had medical evaluation results (including the above-mentioned autopsy report) that were consistent with new-onset asthma or exacerbation of pre-existing asthma. Four employees reported asthma and/or recurrent bronchitis while working on the fluid-fill deck. One of these four employees provided medical records which showed reversible airways obstruction consistent with asthma on lung function tests. JNAP employees can be exposed to many agents with potential to induce or aggravate respiratory illness. Some employees may be affected by the combined effects of exposure to several irritants in the form of dusts, fumes, and gases. This will be more likely when ventilation is decreased due to mechanical breakdowns or in an attempt to decrease heating costs during winter months. Regulatory compliance with exposure limits does not ensure that all workers are protected. The potential for exposures in automotive assembly plants to cause occupational respiratory problems has not yet been adequately assessed. Symptoms and illnesses in employees suggest that additional medical monitoring and control of exposures at JNAP should be implemented and detailed studies to assess occupational health risk conducted. JNAP management should implement the recommendations provided in this report to minimize the potential risk to employees from welding-related and other exposure sources in the plant.