Previous air quality studies have shown that the area inside enclosed train stations is of particular concern, especially when idling diesel trains are present. Air quality monitoring of train stations was limited in the past and so a need to develop and operate a monitoring network for stations in the UK has been recognised. This will aim to achieve the following at stations across GB rail:

  • Provide air pollution information across the rail network, focussing on train stations.
  • Provide location-specific air quality information to prioritise improvement initiatives.
  • Assess the effectiveness of policies and mitigation measures to improve air quality.
  • Inform the public about air quality at train stations.
  • Establish the most accurate and cost-effective air quality monitoring solutions.

Scope of work

The key considerations for the AQMN programme are described below:

  • Monitoring key pollutant of concern to public health:
  1. Diffusion tubes are passive acrylic tubes usually attached to columns like lampposts or water pipes. This is the industry standard technique for monitoring ambient air quality, it is well established especially around the road network and is a cost-effective way to determine long-term monthly NO2 concentrations.
    The most advanced form of diffusion tubes (the same as those used in the UK Urban NO2 Network) have been installed in all stations within the network. There are an average of five monitoring locations per station.
  2. Reference monitors fulfil continuous monitoring requirements as stated in the relevant EU and UK Directives.
  3. Low-cost sensors are monitoring equipment that are designed to measure pollutant concentration in ambient air, unlike reference monitors these do not adopt the reference methods. They are often available at significantly lower cost than reference monitors.

October 2023 status

The AQMN started operating in 2022 with monitoring equipment installed in phases at the selected train station.

At present, diffusion tubes have been installed at all the selected stations, capturing up to 20 months of data. Reference monitors have been installed at Birmingham New Street, Sunderland and London Marylebone, with two more units to be installed at Hull and Sheffield in the near future. The roll-out of low-cost sensors will be determined pending further field trial.