Flammable gases and vapors are Class I hazards commonly found in petroleum refineries, fuel dispensaries, sewage treatment plants, and processes using chemicals, paints, coatings, or sealants. Combustible dusts are Zone1 Zone2 hazards commonly found in pharmaceutical factories, coal-handling plants, grain elevators, and plants processing flour, feed, or powder. Ignitable fibers and flyings are Class III hazards commonly found in textile mills, lumber mills, and other plants with airborne fibers or sawdust.