Since the 1970s, the U.S. National Institute for Occupational Safety and Health has monitored a cohort of 5,204 workers from two reinforced plastic boat–building facilities where exposures to styrene were characterized (1–3). Styrene is a volatile organic compound used during fiberglass production (4). An analysis of this cohort demonstrated that short-tenured workers with high styrene exposures had elevated standardized mortality ratios for nonmalignant respiratory disease (1.99; 95% confidence interval [CI], 1.38–2.79) and chronic obstructive pulmonary disease (COPD) (2.60; 95% CI, 1.70–3.81) (2). | These findings are noteworthy considering that nine cases of obliterative bronchiolitis have been reported after employment in similar industries that use styrene to make reinforced plastics (5). Nontransplantation-associated obliterative bronchiolitis occurs rarely after occupational exposure to inhalational toxins (6). In addition, rodent models have demonstrated damage to the respiratory epithelium after inhalational exposure to high concentrations of styrene (7–10). We hypothesized that styrene-related obliterative bronchiolitis contributed to the excess burden of nonmalignant respiratory disease mortality in this cohort but went unrecognized and was incorrectly categorized on death certificates as COPD (11). We therefore aimed to describe any decedents from this cohort who died of nonmalignant respiratory disease and who had possible underlying obliterative bronchiolitis.