basically an inert material that must be heated or diluted to a point where it becomes workable for the production of materials for paving, roofing, and other applications. In examining the potential health hazards associated with bitumen, the International Agency for Research on Cancer (IARC) determined that it is the application parameters, predominantly temperature, that affect occupational exposure and the potential bioavailable carcinogenic hazard/risk of the bitumen emissions. In particular, temperatures greater than 199 °C (390 °F), were shown to produce a greater exposure risk than when bitumen was heated to lower temperatures, such as those typically used in asphalt pavement mix production and placement. IARC has classified paving asphalt fumes as a Class 2B possible carcinogen, indicating inadequate evidence of carcinogenicity in humans. In 2020, scientists reported that bitumen currently is a significant and largely overlooked source of air pollution in urban areas, especially during hot and sunny periods. A bitumen-like substance found in the Himalayas and known as shilajit is sometimes used as an Ayurveda medicine, but is not in fact a tar, resin or bitumen. See also Asphalt plant Asphaltene Bioasphalt Bitumen-based fuel Bituminous rocks Blacktop Cariphalte Duxit Macadam Oil sands Pitch drop experiment Pitch (resin) Road surface Tar Tarmac Sealcoat Stamped asphalt Notes References Sources Barth, Edwin J. (1962), Asphalt: Science and Technology, Gordon and Breach. . External links Pavement Interactive – Asphalt CSU Sacramento, The World Famous Asphalt Museum! National Institute for Occupational Safety and Health – Asphalt Fumes Scientific American, "Asphalt", 20-Aug-1881, pp. 121 Amorphous solids Building materials Chemical mixtures IARC Group 2B carcinogens Pavements Petroleum products Road construction materials