Tunnel Monitoring

tunnelAirQuality Ltd offers a unique solution to monitoring the emissions from emission sources such as tunnels.

Traditionally emissions from these sources have been difficult to predict and it is not always clear what the impact of emissions from these facilities will have on surrounding residents.


Airquality Ltd can establish a network of cost effective gas sensitive semiconductor NO2 monitors to precisely measure the concentration of this pollutant around the tunnel exit. This can allow a relationship between NO2 concentration, fan speed and the number of vehicles to optimise the use of ventilation fans.

This technique has the advantage of minimising the use of expensive ventilation technology while ensuring that ambient concentrations of NO2 do not exceed relevant standards or guidelines.

This technique uses a combination of cost-effective GSS sensors with reference monitoring stations as ‘anchor points’.


There are a variety of options for monitoring emissions depending on your requirements. Normally a network of sub-reference analysers is deployed in conjunction with a reference analyser. Analytical software is run to continuously check and verify the status of the network and confirm the instruments are operating correctly. More details on each of the network components is shown below:

Nitrogen dioxide – Gas Sensitive Semiconductors
We recommend the use of gas sensitive semiconductors. These cost effective instruments send data to a secure on-line repository. We provide our clients with access to a web server to view plots of real-time data. Data can then be compared with national standards and guidelines. If the levels are close to relevant limits or legal certainty and compliance wi


Pricing is dependent upon:

  • The length of time you wish to monitor for
  • The type of equipment you wish to use
  • Whether you wish to purchase or rent the monitoring instrumentation
  • The level of data validation and reporting
  • Whether an instrument enclosure is required
  • Whether mains or solar powered options are required
  • Whether wind speed and direction also need to be measured

Our clients tell us that we offer very competitive quotes for both the supply and operation of these instruments.

Contact us today for an obligation free quote