Vaisala Air Quality Transmitter AQT420


Vaisala Air Quality Transmitter AQT420 measures the most common gaseous pollutants nitrogen dioxide (NO2), sulphur dioxide (SO2), carbon monoxide (CO) and ozone (O3 ) with default configuration, plus Particulate Matter (PM2.5 and PM10 ) in the ambient air. The AQT420 measurement performance is based on proprietary advanced algorithms that enable ppb measurements at an affordable price using electrochemical sensors. The algorithms compensate the impact of ambient conditions and aging on the sensor elements and remove the need for costly gas sampling and conditioning equipment.

AQT420 has been specifically designed for air quality monitoring networks in urban areas, road networks or around industrial sites and transportation hubs. Thanks to its small weight and compact size it is ideally suited for deployment even in large air quality networks. The measurement data is sent wirelessly to a web-based database with GSM Gateway or is available locally via a serial interface. Depending on local conditions the AQT420 has a maintenance and calibration interval of 12-24 months.


  • Urban air quality networks
  • Industrial emission monitoring
  • Safety monitoring
  • Roadside and tunnel monitoring
  • Mobile measurement
  • Building automation
  • Air quality research


  • Measures up to four most common air pollutants NO2, SO2, CO and O3.
  • Intelligent algorithms that compensate for aging and environmental conditions
  • Compact design, easy to deploy in the field
  • Low power consumption (typically 0.5W)
  • Wireless Internet connection with Multi-Observation Gateway
  • RS232 and RS485 interfaces for local connectivity (eg. Modbus support)
  • Easy integration and open API
Technical Specifications
Data protocolsModbus, ASCII
Serial data interfaceRS-485
Console interfaceRS-232
Power and data connectorStandard 8-pin M12 male
Operating voltage8 — 30 VDC
Power consumptionTyp. 0.5 W, max. 2 W
Protection classIP65
Enclosure materialsAnodized aluminum, stainless steel
Dimensions128(w) x 185(h) x 128(d) mm
Weight1250 g
Measurement Specifications
Temperature range-40 — 85 °C
Temperature resolution0.1 °C
Temperature accuracy±0.3 °C, repeatability ±0.1 °C
Humidity range0 — 100 %RH (non-condensing)
Humidity resolution0.1 %RH
Humidity accuracy±2 %RH, repeatability ±0.2 %RH
Pressure range800 — 1100 mbar
Pressure resolution1 mbar
Pressure accuracy<±1 % FS
Air Quality Measurement Specifications
Temperature range-30 — 50 °C
Humidity range15 — 95 %RH (non-condensing)
Gas Measurement Specifications
SO20 — 20.005±0.001<±1 % FS<±1 % FSppm
NO20 — 20.005±0.001<±1 % FS<±1 % FSppm
CO0 — 100.01±0.01<±2 % FS<±2 % FSppm
O30 — 20.005±0.01<±3 % FS<±2 % FSppm
Particle Measurement Specifications
Particle counter channelsPM2.5 and PM10
Particle range0.3 — 20 µm (spherical equivalent)
Response time<60 s
Sampling interval1 — 1440 minutes
Sample flow rate0.5 SLM (integrated vacuum pump)
Measurement range for PM2.50 — 2000 µg/m3
Measurement range for PM100 —5000 µg/m3
Measurement resolution0.1 µg/m3
EMCIEC/EN 61326-1, IEC/EN61000-4-2/3/4/5/6, CISPR 22I
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