The incidence of pneumoconiosis of 1413 subjects in ouv ferroalloy works was obsered in the period of 1963-1983.The results revealed that the amount of dust concentration is 14.6 mg/M3

theredy 26 patients with pneumoconiosis were detected and ith a total prevalence rate(morbidity)of 1.84%

4 cases with pneumoconiosis result in contacting finesized ferroalloy

preferably in ferroal-loy-smeltng works with a prevalence rate (morbidity) of 0.38%. There is no difference in comparing with smelting works. Relation for the amount of dust absorbed in one’s working life to morbidity of pneumoconiosis with life table method showed that expectant morbidity of pneumoconiosis prevalence fate (controlled) being 0.5% and then allowed concentration for cnntacting dust of ferroalloy controlled should be 13mg/M3 during 30 years contacting dust