182 CO poisoning cases were identified as occurring over a 6-year period in the West Virginia workers' compensation data. Frequent sources of poisoning were gas-powered engines (28%) and furnaces (20%). Minimum treatment duration ranged from 1 day to 8 years with significant differences in mental health comorbidities between cases treated within 1 year compared with cases treated for more than 1 year . The average cost (medical and wage loss replacement) for CO claims was $2130 and median lost time was 45 days. CO poisoning could lead to prolonged disability and treatment in patients with mental health comorbidities, suggesting a possible role for early intervention.