"Hexavalent chromium, or chrome 6, is a form of chromium that can be found in welding fume when “hot work” is done on metals, such as stainless steel, that contain chromium. Exposure to fumes from welding, cutting, and other hot metal work is a recognized hazard for welders, and chrome 6 has been receiving increased attention from federal and state agencies in charge of protecting workers’ health. Research has shown that workers exposed to chrome 6 are at an increased risk of developing lung cancer, and welders are the largest worker population potentially exposed to this known carcinogen. In order to reduce occupational exposure to chrome 6, in February 2006, the federal Occupational Safety and Health Administration (OSHA) implemented a standard, which significantly lowered the permissible exposure limit (PEL) from 50 to 5 micrograms per cubic meter (µg/m3), as an 8-hour time-weighted average (TWA). The regulation also outlines other requirements to protect workers from exposure. The previous PEL was actually 100 µg/m3 for chromates (a form of chrome 6), which corresponds to 52 µg/m3 as chromium. Working safely with chrome 6 is a shared responsibility for welders, engineers, employers, and safety officers. This training package, Hexavalent Chromium Exposure Control: Best Practices for Welders (HexChEC), is a video-based program developed to raise awareness among Washington state welders and their employers about chrome 6, the standard, health effects of exposure, and best practices for exposure control—with an emphasis on local exhaust ventilation."

Source: http://staff.washington.edu/vrunnion