MSSI impactor is realized according to ISO23210 norm for the nozzle dimensioning. The impactor allows the simultaneous determination of total dust, PM10 and PM2.5 fractions (PM4 stage also available). The impactor can be supplied with two different inlet cones to allow the vertical and horizontal sampling, depending on the stream direction into duct (fig. 1 and 2). The impactor is designed for a high sampling flowrate, about 2 m3/h, depending on emission characteristics, to reduce sampling time. The device is supplied with a dedicated software, which allows to calculate sampling flowrate, nozzle and others factors to optimize the quality of the measurement.