Lung Function Status of Some Ethiopians Exposed to Occupational Dusts

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Addis Ababa University


Acute and chronic changes of ventilatory capacities and the prevalences of respiratory symptoms were studied in 233 (117 males and 116 females) nonsmoking factory workers exposed to cotton, tobacco and cement dusts. Two hundred and thirty six (125 males and 111 females) workers who were nonsmokers and had no exposure to occupational dusts were taken as non-exposed subjects. An attempt was made to see values of ventilatory indices in relation to dust concentration and duration of exposure. Comparison was also made between dust concentrations recorded in this study and standards recommended by ACGIH and WHO. Prevalences of respiratory symptoms (chronic cough, chronic bronchitis, and bronchial asthma) were found to be higher in all dust-exposed groups than they were in the non-exposed subjects. All respiratory symptoms considered in the present study were found in cement and cotton workers much more frequently than in the non-exposed sUbjects. Only chronic cough was found to be more frequent among tobacco workers than among the non-exposed sUbjects. significant reductions of FVC, FEV1, MMFR and PEFR values over the workshift were recorded among cotton and tobacco workers. Acute reductions in cement workers were recorded only in FVC and PEFR. Significantly reduced mean values of FEV1%, FEF , MMFR in both sexes of exposed subjects and FEV1 and PEFR in male Exposed subjects were recorded. After matching of exposed subjects, from each factory, with the non-exposed subjects according to their age and height, significantly reduced mean values of FEV1%, FEF, MMFR in both sexes of cotton workers and PEFR in male cotton workers were recorded. Mean values of FEVl% and MMFR in cement workers, FEVl in female tobacco workers and PEFR, MV and MVV in male tobacco workers were found to be significantly lower than in the non-exposed sUbjects. Substantial number of workers were found to have lower values of ventilatory capacities than their predicted values by more than two standard errors of estimate. Predicted values of ventilatory indices were calculated for both sexes by means of multiple linear regression equations, developed on the basis of data obtained in the non-exposed subjects. Mean percentages of predicted lung function values in workers exposed to relatively high dust concentration were found to be lower than the values observed in those exposed to lower concentration, but significant differences (in FEVl %) were observed only in cement workers. strong negative correlations (rS-O.30) were recorded between duration of exposure and FVC, FEVl , FEV1% and MMFR values in male exposed subjects. Negative correlations were also observed among females, but the relationships were not as strong as that of males. When compared with standards of ACGIH and WHO, the dust concentrations in cement and yarn factories were found to be high.