Hazards associated with use of bedding choppers in dairy barns were considered in this leaflet. During the chopping of bales of hay or straw for dairy cow bedding, microorganisms such as bacteria or fungi may released into the air in such quantities as to cause respiratory hazards. These hazards include acute and chronic respiratory and systemic problems such as asthma, chronic bronchitis, hypersensitivity pneumonitis, and organic dust toxic syndrome. By the addition of small quantities of water to the bales of hay and straw before chopping, worker exposure to airborne organic dusts can be reduced 80%. To guard against the remaining dust generated, additional controls may be used. Control methods included substituting less contaminated hay for bedding chopping when bales are visibly contaminated with mold, and use of respiratory protective equipment. Carbon-monoxide (630080) poisoning may result from using gasoline powered bedding shoppers, and other gasoline powered engines inside barns and other structures. Ventilation should be improved, and the use of electrically powered bedding choppers can eliminate this hazard.