Correlations of smoking with cumulative total dust exposure and cumulative abnormal rate of pulmonary function in coal-mine workers

The present study aimed to investigate the correlation of smoking with cumulative total dust exposure (CTE) and cumulative abnormal rate of pulmonary function in coal-mine workers. A total of 376 coal-mine workers were recruited as the observational group, while 179 healthy workers in other industries were selected as the control group. All the workers underwent pulmonary function testing to determine their forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1) and FEV1/FVC, in order to compare the abnormal pulmonary function between the two groups. A markedly higher number of smokers was observed in the observational group (200/376, 53.19%) when compared with the control group (72/179, 40.22%). In smokers, the abnormal rate of pulmonary function in the observational group (102/200, 51.00%) was evidently higher compared with that in the control group (19/72, 26.39%), whereas no significant difference was detected between the two groups of non-smokers (P=0.077). In addition, FVC, FEV1 and FEV1/FVC of the observational group were found to be lower compared with those in the control group, in both the smoking and non-smoking subgroups. In the smoking subgroup, FVC and FEV1 in subjects working at the coal mine for different number of years showed significant differences (all P<0.05), whereas comparison of FEV1/FVC in workers with different working durations showed no significant difference (P=0.169). However, in the non-smoking subgroup, the comparison of FVC, FEV1 and FEV1/FVC in different working duration groups also showed no significant difference (all P>0.05). Furthermore, FVC, FEV1 and FEV1/FVC in smoking coal-mine workers were negatively correlated with the dust-exposure working duration (P<0.05). CTE was also positively correlated with cumulative abnormal rate of pulmonary function in the smoking and non-smoking subgroups, while FEV1 was negatively correlated with CTE in the smoking subgroup (P=0.009). In conclusion, smoking is an important risk factor for the damage of pulmonary function in coal-mine workers, and it is positively correlated with dust-exposure time and CTE in these individuals.