According to previous studies, air quality inside enclosed train stations is of particular concern, especially when idling diesel trains are present.

However there is very limited monitoring data for air quality at other train stations across the country. Therefore, there is a need to develop and operate a monitoring network for stations in the UK to achieve the following:

  • Provide information on the current state of air pollution across the rail network.
  • Provide location specific air quality information to prioritise improvement in the highest risk locations.
  • Assess the effectiveness of policies and mitigation measures to improve air quality at stations.
  • Inform the public about air quality at train stations.
  • Establish the most accurate and cost-effective air quality monitoring solutions for rail.

Scope of work

DfT funding awarded to RSSB will support the Stations AQMN. The key parameters for the monitoring programme are described below.

  • Monitoring will be carried out at 105 train stations across the entire UK rail network, which the coverage will be reviewed after 12 months.
  • The monitoring network will commence by the end of 2021 and will last until December 2023 for the current project.
  • The pollutants to monitor will include nitrogen oxides (NOx), nitrogen dioxide (NO2), and particulate matters (PM, including PM10 and PM2.5).
  • Monitoring will be carried out using a variety of monitoring equipment:
  1. Diffusion tubes are passive acrylic tubes usually attached to columns like lampposts or water pipes. The use of diffusion tubes to monitor ambient air quality is well established in the road sector and is a cost-effective way to determine long-term NO2 concentration levels. The newly developed diffusion tubes (same as those used in the UK Urban NO2 Network) will be installed in all stations within the network, at on average five representative locations per station.
  2. Reference monitors are state-of-the-art monitors that fulfil the monitoring requirement as stated in the relevant EU and UK Directives. These monitors will be rolled out to up to 10 key stations.
  3. Low-cost sensors are monitoring equipment that are designed to measure pollutant concentration in ambient air, but do not adopt the reference methods as per the reference monitors. They are often available at significantly lower cost than reference monitors. The scope for low-cost sensors deployment is to be confirmed.

The process to deploy the diffusion tubes has commenced, with the target to complete the installation at all 105 stations by the end of 2021.

The first two reference monitors are currently scheduled to be installed in Spring 2022. In addition near-reference real-time PM monitors will be installed at 20 stations in Spring 2022 to gather additional baseline PM concentration, before the wider roll-out of reference monitors within the network.

A trial of selected low-cost sensors will be carried out in Spring 2022 to determine their performance in a train station environment and hence their suitability for the AQMN. Further update on the project will be provided on this webpage.