The information in this document assesses the health hazards associated with occupational exposure to asphalt. Chapter 2 presents information about the uses of asphalt and the number of workers potentially exposed to asphalt during paving and roofing operations and during the manufacturing of asphalt roofing products. Chapter 3 describes the chemical and physical properties of asphalt, production methods, similarities and differences between paving and roofing asphalts and asphalt-based paints, and the representativeness of field- and laboratory-generated asphalt fumes. Chapter 4 discusses exposure monitoring methods extent of worker exposure, and estimates of biological responses in asphalt-exposed workers. Subsequent chapters describe the effects of exposure to asphalt and asphalt fumes on humans and animals, conclusions, recommendations, and needed research.