The occupational exposure limit (AGW) is a legally established value that indicates the maximum concentration of a substance in the air at the workplace in order not to endanger the health of employees. The OEL is usually given in milligrams per cubic meter (mg/m³) or parts per million (ppm) and refers to the average exposure over a certain period of time (e.g. 8 hours per day). The determination of workplace limit values ​​is based on scientific knowledge and experience and serves to minimize work-related health risks. The AGW is set by various institutions such as the European Union, the Ministry of Labor or the professional association and is regularly updated to reflect the current state of science and technology.