Chronic obstructive pulmonary disease and smoking in grain workers.
D000402:Airway Obstruction / Q000209:etiology; D002908:Chronic Disease; D002523:Edible Grain; D006801:Humans; D008173:Lung Diseases, Obstructive / Q000209:etiology* / Q000503:physiopathology; D008450:Maximal Midexpiratory Flow Rate; D009784:Occupational Diseases / Q000209:etiology* / Q000503:physiopathology; D012907:Smoking / Q000150:complications*; D013147:Spirometry