Abstract: To study the effects of epidemic factors on arsenism caused by burning coal,the exposure factors of 151 patients with arsenism of different degrees of severity,16 controls in the endemic arsenism area and 53 controls outside the endemic arsenism area were evaluated with cumulative odds model.The results suggested that the major risk factors were,as listed in a order of their effect on arsenism,period of burning hyperarsenic coal,bad room ventilation,high arsenic content in hair and urine,cigarette smoking,and fluorine poisoning(OR>1,P<0.05).The contributing factors were educational level and family economy state(OR<1,P<0.05).It is suggested that multiple measures be adopted to prevent arsenism caused by burning coal.