Prevalence of spirometry-defined airflow obstruction in never-smoking working US coal miners by pneumoconiosis status.

INTRODUCTION: This study estimated the prevalence of spirometry-defined airflow obstruction and coal workers' pneumoconiosis (CWP) among never-smoking coal miners participating in the National Institute for Occupational Safety and Health (NIOSH) Coal Workers' Health Surveillance Program (CWHSP). METHODS: Data were from working miners screened by a CWHSP mobile unit who had valid spirometry and chest radiography results. Spirometry-defined airflow obstruction was determined when the ratio of forced expiratory volume in the first second to forced vital capacity is less than the lower limit of normal. Chest radiographs were classified according to the International Labour Office system to identify pneumoconiosis, including the most severe form of pneumoconiosis, progressive massive fibrosis (PMF). RESULTS: Prevalence of airflow obstruction among never-smoking coal miners in this sample was 7.7% overall, 16.4% among miners with CWP and 32.3% among miners with PMF. Airflow obstruction was significantly associated with CWP and PMF. CONCLUSIONS: There was a higher prevalence of airflow obstruction among never-smoking coal miners with pneumoconiosis compared with those without pneumoconiosis. These findings support prior research on airflow obstruction and smoking and show pneumoconiosis might present with an obstructive pattern regardless of smoking status.