Objective To explore the impact of dust exposure on respiratory function, and to discuss the application of small airway function test in occupational health surveillance and pneumoconiosis risk assessment of workers exposed to dust.
Methods A worksite survey of occupational environment and dust concentration was conducted in the dust workshop of a machinery enterprise in 2009. Occupational health examinations and questionnaires were provided to 216 workers exposed to dust.
Results The median of forced expiratory flow at 75% of forced vital capacity (FVC) (FEF75%) in the selected workers was 79% (below the normal range). The mean or median of FVC, forced expiratory volume in one second (FEV1), FEV1/FVC, peak expiratory flow (PEF), FEF25% and FEF50% were in the normal ranges. The proportions having abnormal PEF, FEF25%, FEF50% and FEF75% increased significantly, being 21.30%, 30.56%, 45.37% and 50.00% respectively, and the corresponding medians of dust exposure period were 3.5, 4, 5 and 5 years respectively. The proportions showing abnormal chest X-ray images in workers having abnormal FVC, FEV1, FEV1/FVC, PEF, FEF25%, FEF50% and FEF75% were 55.56%, 60.00%, 0, 21.74%, 15.15%, 23.47%, 25.00%, respectively. The values of PEF, FEF25%, FEF50% in workers showing normal chest X-rays were significantly lower than those with abnormal X-rays (P < 0.05). The abnormal proportions of FEV1, FEF25% and FEF75% in workers exposed to dust over 10 years was significantly higher than those with shorter exposure period (P < 0.05).
Conclusion Workers exposed to dust suffered airflow limitation with small airway dysfunction. With the extension of dust exposure time-length, there is a rising tendency of the number of workers with abnormal FEV1, FEF25% and FEF75% values. The results of pulmonary function test and chest X-ray are not synchronized in this study. Small airway function could be used as one of the dust exposure worker surveillance indicators for dynamic observation and analysis.
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