Fixed gas monitoring systems check the measurement location reliably and quickly and increase the security without requiring additional labour intensive inspections to be carried out. Gases are produced, used or stored in many areas of industry and research. Hazards can already occur from very small amounts of gas that are not directly noticed by the people. To protect human health, the environment and production, there is an obligation to avoid or avert potential hazards from toxic or flammable gases. This includes continuous monitoring of the gas concentration in the air.