ISO 29042-9:2011 specifies a method for the measurement of the decontamination index of pollutant control systems, e. g. capture devices including local exhaust ventilation, water spray systems and, when appropriate, separation equipment installed on a machine. This method uses the real pollutant (see ISO 29042-1:2008, 4.2) and can be operated in room or field environments.Measurement of the decontamination index of a pollutant control system can serve for the: a) evaluation of the performance of a pollutant control system of a machine; b) evaluation of the improvement of a pollutant control system; c) comparison of pollutant control systems for machines of similar design; d) ranking of pollutant control systems according to their decontamination efficiency; e) determination of the air flow rate in the case of an exhaust system to achieve a given level; f) determination of the state of the art of pollutant control systems for machines with respect to the decontamination efficiency.