To study the early effects of coal dust on lung function in new underground coal miners.
Two hundred and eighty-seven male miners were selected from new employees at the Xuzhou Mining Group Company as study group, and 132 male students at a mining technical school were selected as control. Data collection included: individual demographic parameters, family medical history, occupational history, and smoking history, measurement of dust concentrations in work areas, and lung function tests. This prospective cohort study took place over 3 years during which time total dust and respirable dust concentrations in the new coal miners' work areas were measured twice each month. For both miner and student groups, FVC and FEV(1) were tested initially before dust exposure, and then 15 times over the 3 years.
The average total dust and respirable dust concentrations in the miners' work areas were 23.8 mg/m(3) and 8.9 mg/m(3) respectively, which greatly exceeded national health criteria. During the first year of dust exposure, the miners's average FVC was higher than that of the controls (5.19 L vs 4.92 L, P < 0.01). During the 2nd and 3rd year the difference in average FVC between miners and control group was not significant (5.14 L vs 5.12 L, P > 0.05). Before dust exposure, the miners' FEV(1) was significantly higher than that of the control group (4.48 L vs 4.28 L). In the miners group, FEV(1) declined rapidly during the first year following dust exposure (from 4.48 L to 4.25 L), and in the 2nd and the 3rd year the average FEV(1) of the miners was significantly lower than that of controls (4.34 L vs 4.56 L, P < 0.01), although there were some fluctuations during the follow-up period. Overall, the average FEV(1) of miners group showed a significant decline during the study. There were significant correlations between FVC or FEV(1) and age, height, weight, and smoking. The three-year total loss of FVC and FEV(1) in smoking miners (154 ml, 184 ml) were greater than in non-smoking miners (83 ml, 91 ml).
There are apparent effects of coal dust on lung function in new underground coal miners, with FEV(1) being more impacted than FVC. Smoking may aggravate the effect of dust exposure on reducing lung function.