Objective To explore the effects of refractory ceramic fibers on workers' pulmonary ventilation function.
Methods This study enrolled 265 manufacturing and processing workers as the exposure group and another 273 workers only exposed to noise as the control group.All subjects accepted pulmonary function test with indicators including forced vital capacity (FVC),forced expiratory volume in 1 s (FEV1.0),and FEV1.0/FVC,represented in percentages of measured values over expected values (FVC%,FEV1.0%,FEV1.0/FVC%).Low,medium,and high exposure subgroups were divided by the number concentration of fiber < 0.1,0.1-0.5,and > 0.5 f/mL and by the gravimetric concentration of total dust < 1,1-5,and > 5 mg/m3.Specifically,81 workers were classified into the low fiber and low total dust subgroup,123 workers in the medium fiber and medium total dust subgroup,30 workers in the medium fiber and high total dust subgroup,and 31 workers in the high fiber and high total dust subgroup.
Results Compared with the control group,the exposure group had significantly lower mean values of FVC%,FEV1.0%,and FEV1.0/FVC%(P < 0.05).The subgroup with high number concentration of fiber and high gravimetric concentration of total dust had significantly greater reduction of FVC% and FEV1.0% than other three subgroups (P < 0.05).Subgroups with different exposure age had no differences in the values of FVC%,FEV1.0%,and FEV1.0/FVC%(P > 0.05).The positive rates of restrictive,obstructive,and mixed pulmonary dysfunction were 58.9%,4.5%,and 3.8% in the exposure group respectively and 10.9%,5.1% and 4.0% in the control group respectively,and only the positive restrictive pulmonary dysfunction rate showed significant difference between the two groups (P < 0.05).The restrictive pulmonary dysfunction was associated with the number concentration of fiber and the exposure age (P < 0.05),and not with the gravimetric concentration of total dust or smoking habit (P > 0.05).
Conclusion Exposure to refractory ceramic fibers can harm the pulmonary ventilation function,mainly restrictive pulmonary dysfunction.The positive rate of restrictive pulmonary dysfunction has a positive correlation with the cumulative number concentration of fiber,and shows superior correlation with the number concentration of fiber to the gravimetric concentration of total dust.
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