Objective To examine the relationship of cumulative dust dose and cumulative abnormal rate of pulmonary function in workers on mixing coal mining working face.
Methods Mixing coal mining workers (n=328) were selected from a coal mine in Tangshan as observation group, and non-dust exposed workers (n=169) were selected as control group. A survey collecting basic information (such as name, gender, date of birth, working conditions, working environment, dust species, and dust exposure history) and a pulmonary ventilation function test were conducted among them.
Results The abnormal rate of pulmonary function in the observation group (35.1%) was higher than that of the control group (10.1%) (P<0.05). Lung function indicators including forced vital capacity, forced expiratory volume in one second, and the percentage of forced vital capacity to forced expiratory volume in one second in the observation group were lower than those in the control group (P<0.05). With the increasing of service length, the lung function indicators decreased significantly (P<0.05). With the cumulative dust dose increasing, the cumulative abnormal rate of pulmonary function in the observation group increased from 0.33% in the 100 mg/m3-group to 98.41% in the 1 700 mg/m3-group. Steeper increases in the cumulative abnormal rate of pulmonary function were found in the cumulative dust exposure dose ranging from 1 000 mg/m3 to 1 700 mg/m3. Cumulative dust dose demonstrated a positive correlation with cumulative abnormal rate of pulmonary function (r=0.759, P=0.000).
Conclusion The cumulative abnormal rate of pulmonary function increases with higher cumulative dust dose. Within the cumulative dust exposure range of 1 000 -1 700 mg/m3, the cumulative abnormal rate rapidly grows.
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