Urban air quality monitoring - Air and Climate - Air Monitoring and Testing

To measure air quality in the ambient air is a challenge. The monitoring site needs to be representative and not dependant on changes in local traffic. A large number of gaseous components need to be measured with high accuracy and high availability.

The OPSIS DOAS system is different and provides a fast monitoring system that gives high data availability at low cost.

The OPSIS system is based on a non-contact DOAS method, using an optical path. The optical light is transferred in an optical fibre to the analyser and one analyser can operate several paths.

A single OPSIS system will measure all relevant gaseous components, such as NO, NO2, SO2, O3, BTX, HNO2, NO3, formaldehyde, and NH3.


  • High data availability
  • Cost-effective, open-path technology
  • Representative path-integrated data
  • Direct monitoring of NO2
  • Gas calibration only once per year
  • Low energy consumption
  • Operates with a minimum of maintenance
  • Approved by MCERTS, TÜV, U.S. EPA, Chinese EPA, and others

System Overview