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Chronic obstructive pulmonary disease mortality in railroad workers
  1. J E Hart1,2,3,
  2. F Laden1,2,3,
  3. E A Eisen1,
  4. T J Smith1,
  5. E Garshick2,4
  1. 1
    Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts, USA
  2. 2
    Channing Laboratory, Brigham and Women’s Hospital and Harvard Medical School, Boston, Massachusetts, USA
  3. 3
    Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts, USA
  4. 4
    Department of Veterans Affairs, Harvard Medical School, Boston, Massachusetts, USA
  1. Jaime E Hart, Channing Laboratory, 181 Longwood Ave, Boston MA 02115, USA; Jaime.hart{at}


Background: There is little information describing the risk of non-malignant respiratory disease and occupational exposure to diesel exhaust.

Methods: US railroad workers have been exposed to diesel exhaust since diesel locomotives were introduced after World War II. In a retrospective cohort study we examined the association of chronic obstructive pulmonary disease (COPD) mortality with years of work in diesel-exposed jobs. To examine the possible confounding effects of smoking, multiple imputation was used to model smoking history. A Cox proportional hazards model was used to estimate an incidence rate ratio, adjusted for age, calendar year, and length of follow-up after leaving work (to reduce bias due to a healthy worker survivor effect).

Results: Workers in jobs with diesel exhaust exposure had an increased risk of COPD mortality relative to those in unexposed jobs. Workers hired after the introduction of diesel locomotives had a 2.5% increase in COPD mortality risk for each additional year of work in a diesel-exposed job. This risk was only slightly attenuated after adjustment for imputed smoking history.

Conclusions: These results support an association between occupational exposure to diesel exhaust and COPD mortality.

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  • Funding: Grant information: Grant Sponsor: NIOSH Grant Number: CCR115818 and NIH/NCI Grant Number: CA79725.

  • Competing interests: None.