Hard metal workers requested that we investigate their worksite because three workers had been diagnosed with hard metal disease or occupational asthma. Volunteers completed questionnaires, spirometry, bronchodilator trial, and lung diffusing capacity (DLCO). We defined suspected occupational asthma (OA) as post-hire-onset asthma, at least three asthma symptoms, or reversible airways obstruction; and suspected hard metal disease (HMD) as a total lung capacity lower than 80% of predicted with DLCO below the lower limit of normal or restriction on spirometry. Work histories and symptom/disease onset dates were used to calculate work area-specific suspected OA incidence rates and to identify work areas where suspected HMD began. Historical personal cobalt air monitoring results were used to estimate cobalt exposures by work area. Of 243 workers, 171 (69%) participated in the study. Suspected OA incidence rates were highest in powder plant maintenance, product testing, pressing, and sintering. Suspected HMD cases occurred in pressing, sintering, and grinding. For the above listed possible high-risk areas, geometric mean cobalt air levels (where results were available) ranged from 8.2 (sintering) to 45.8 g/m3 (pressing) compared to < 0.1 to 139.2 g/m3 for other work areas. Work-related respiratory morbidity in low exposure areas motivates further exposure characterization, including particle physicochemical properties (size, surface area, chemistry), dermal exposures, and peak inhalation exposures.