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Air Quality Monitor (AQM)

Development of an Air Quality Monitor for Continuous Measurement of the Concentrations of
Suspended Particulate Matter (SPM) and Gaseous Pollutants

This project aimed to develop a compact device for simultaneous mobile non-industrial measurement of the particulate matter fractions PM10 and PM2.5 as well as inorganic pollutants (NOx / CO / O3 / SO2).


Within the BIG FuE project “Entwicklung eines Air Quality Monitors zur mobilen, nicht-industriellen Messung der PM10– und PM2,5-Fraktion und gasförmiger Schadstoffe”, a compact and mobile device for monitoring certain air pollutants has been developed. The device determines the concentration of suspended particulate matter fractions PM10 and PM2.5 and simultaneously the concentration of the health-endangering gaseous pollutants sulfur dioxide (SO2), nitrogen dioxide (NO2), ozone (O3) and carbon monoxide (CO). Additionally, the measurement of VOCs (volatile organic compounds) has been integrated and tested.

The method applied by the Air Quality Monitor (AQM) uses light scattered by tiny particles (nephelometry). A scattered light photometer detects the mass concentration of the aerosol particles within the measuring space. The wavelength of 650 nm applied by the system is most sensitive to particles in the size range from 0.5 to 1 μm. To improve the sensitivity of the coarse fraction PM2.5 to PM10, the AQM uses its virtual impactor, situated upstream of the photometer, which selectively enriches the concentration of the coarse fraction. The measurement of gaseous pollutants by way of independent sensor modules is executed simultaneously with. Advanced semiconductor sensors register the concentrations of O3, NO2 and CO; for the determination of the SO2 concentration, an electrochemical sensor is used.

The first functional models have been given to international launch customers in 2018. Their testing results were considered during adjustment development. Field tests have been performed at different locations and under various load situations. To examine the data transmission software, a measurement device has been installed on the motor yacht  MY Victoria II which was cruising on the Havel river. Thus proved that a continuous change of the position of the measurement site has no effect on the quality of data transmission.


Messdaten des AQM bei kontinuierlicher Bewegung der Messstation
Fig. 1: Measurement data of the AQM in continuous movement of the measurement device


In order to evaluate the measurement quality, we performed comparative measurements with devices of competitors, sites of measurement have been in China and Italy.


Fig. 2: Comparison measurement NO2

Technical target criteria

The technical target criterie have been achieved as follows:

  • Detection limit NO2: 10 ppb
  • Detection limit O3: 10 ppb
  • Detection limit CO: 200 ppb
  • Detection limit SO2: 20 ppb
  • Simultaneous measurement of PM2.5 and PM10: achieved for the prototype, not yet available as a product
  • Consideration of cross sensitivities: Cross sensitivities have been examined and are mostly known by now; the consideration of interferences can be realized by calculation in the cloud software.
  • Control panel with color touchscreen
  • Remote access allows remote control and supervision
  • Integration of a cloud solution
  • Data transmission via GPRS/3G/4G, LAN/WLAN, USB and RS-232


Comde-Derenda GmbH stands for innovative measurement technology. The company develops and produces environmental measurement devices with since more than 40 years. Discover a wide range of sampling systems, weighing systems, sampling inlets and other environmental monitoring projects!

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