Another environmental hazard was found to explain the high rates of lung cancer in a county in Montana where workers in this particular copper smelter had an overall 3-fold risk of lung cancer rising to 8-fold among those most heavily exposed to inorganic arsenic. In addition, a study of lung cancer in several areas of the country with arsenic-emitting smelters revealed elevated risks among both men and women with neighborhood exposures to arsenic, even after taking occupation and smoking into account. These studies led to new standards by OSHA and EPA to curtail airborne exposures to arsenic.