Introduction:life is impossible without respiration if we can't breath, the life would stopped after a short time. Respiration means transportation of oxygen to cell and it's consumption in cellular level. This process is possible with the help of respiratory apparatus. The present study has been done in order to determine the respiratory capacities among workers for curing the respiratory apparatus and potential dangers which threaten this vital organ. Materials and methods: This study is analytical and the domain of its investigation is in the range of Ilam province factories with more than 50 personnel who are exposed to harmful chemical factors. all workers have done spearometry test and their demographical features were recorded in order to categorizing the workers in different classes, the proportions of (FEV1/FVC) and (FVC/PFVC) were calculated in relation to their respiratory capacity, by using the miller's standard table and divided according to various amounts of these two proportion in groups with normal respiratory statues, with limiting and obstructing discovers, limiting discovers and obstructive ones. Findings: An analysis was performed after data gathering and calculating the respective proportion by statistical methods and useful software. Research finding: considering the respiratory capacities based on miller's index showed that 43/1 of workers have normal respiratory capacities and the following relations were simultaneously (FVC/PFVC) *100> 75 & (FEV1/FVC) *100>75. A group of workers who have proportional relation with (FVC/PFVC) *100< 75 & (FEV1/FVC) *100<75 were placed in the group of workers with limiting and obstructive disorders and were 29/2 of the investigated society. And finally 27/2 has limiting disorder. No one observed with obstructive disorder. The relation between respiratory condition and worker's background was meaningful (p= 0/039, df = 6, x2 =13/2) Results: the results showed the effect of background on respiratory capacities. as in the group with less than 12 months labor, 46/7 have normal respiratory condition, 34/4 with limiting and obstructive condition and 18/9 with constricting respiratory condition.these percentage be longed to a group with constricting respiratory position, 13-24 months, 27/5 and more than 73 months, 35/5, i.e more increasing background, more increasing the percentage of afflicted people
