This document represents a collaborative effort of the National Institute for Occupational Safety and Health (NIOSH), the National Roofing Contractors Association (NRCA), the Asphalt Roofing Manufacturers' Association (ARMA), the Asphalt Institute (AI), and the United Union of Roofers, Waterproofers, and Allied Workers (UURWAW) to reduce worker exposures to asphalt fumes during the application of hot asphalt to roofs. This guide is for roofers and contractors who work with hot asphalt on roofs. The guide lists steps for reducing exposure to asphalt fumes. Roofers exposed to asphalt fumes may experience the following health effects: headache; eye, nose, throat, and skin irritation; nausea; fatigue; and, drowsiness. These effects appear to be mild and transient. According to some studies, roofers also have an increased risk of lung cancer. But researchers are not sure whether this risk is caused by exposure to asphalt fumes or to other hazards such as smoking, coal tar, or asbestos. In light of this possible health risk and the irritation effects associated with hot asphalt work, it makes sense to take steps to control exposures while government, industry, labor, and independent researchers continue to study these health concerns. NIOSH is working together with industry and labor representatives to find methods that will significantly reduce asphalt fume exposures for roofers and contractors. Efforts are under way to identify new engineering controls and to test their effectiveness in reducing fume exposures at the kettle. To date, studies have shown that the use of fume-suppressing roofing asphalts can reduce fume exposure at the kettle. As these studies are completed, appropriate recommendations will be developed and disseminated.