During cultivation, harmful gases may accumulate unnoticed in the greenhouse. A small amount of ethylene or a short exposure to the crop may already cause invisible damage or interfere with photosynthesis. The MACView®-Greenhouse Gas Analyser provides insight into the gas concentration around the crop. The extreme sensitive instrument measures the concentration of CO2, but also the concentrations of harmful gases, NO, NO2, ethylene and CO at ppb (!) level. Even if the CHP plant and boiler are well maintained, it is necessary to monitor continuously. Very often the CHP plants and boilers are blamed, but not other unknown resources. The cultivation may also be threatened by other sources such as defective by bad-tuned systems, chimneys, leaks in valves and problems in collectors.