Dräger tubes for measuring carbon monoxide, ammonia, hydrogen sulfide, and formaldehyde. The measuring tubes are made of a thin glass tube that is fused at both ends. Inside, there is a chemically reactive filling layer. To take a measurement, the ends of the tube are broken off, and the tube is inserted into the gas detection pump. By compressing the pump, the air to be tested is drawn into the tube, causing the filling layer to change color when it reacts with the corresponding gas. The concentration is read using an integrated scale.