Description: The asphalt roofing manufacturing process yields products that are indispensable to modern society — namely, the shingles that cover the roofs of our homes and businesses and shelter them from the elements. It does, however, result in the generation of hazardous air pollutants (HAPs) that dirty the air if left unmitigated. These HAPs are volatilized during asphalt processing because they are heated and agitated, and because of the oxidation reactions that occur in the blowing still. Sources of particulate matter and gaseous HAP emissions include asphalt storage and process tanks, asphalt blowing stills, asphalt loading racks, saturators, wet loopers, coating mixers, coaters and sealant and adhesive applicators.