Applications: For measurement, control and warnings in garages, for monitoring the air quality with respect to the maximum allowable concentration at work places (MAC value, e.g. in laboratories and engine test benches), for monitoring theoutside air or protected air systems in house shelters or large shelter buildings. Particularly suitable for long-term measurements of the carbon monoxide concentration in air, in a range from 0 … 150ppm to 0 … 5vol%.