SEPA science boosts clean air future as four new Low Emission Zones (LEZs) announced

  31 May 2022
  • Specialists at Scotland’s environmental watchdog SEPA at forefront of science behind Scotland’s clean air future. 
  • SEPA air modelling specialists led on delivery of national modelling framework for the LEZs across four cities. 
  • SEPA aims to improve air quality across Scotland to help achieve national quality standards. 
  • Scientists worked closely with partner local authorities and Transport Scotland. 


The Scottish Environment Protection Agency’s (SEPA) air modelling specialists led on the delivery of the national modelling framework for the LEZs across four cities announced today by Transport Scotland. 

Dr Colin Gillespie, SEPA’s Air Modelling Unit Manager, said: “We welcome today’s milestone which is significant for Scotland and built on science led by SEPA’s air modelling work as part of a partner led approach.  

“Air pollution is one of the most important environmental health risks of our time, so the introduction of LEZs will aim to accelerate air quality improvements in the most polluted areas of our cities. SEPA is proud to play an important part in this collaborative work.” 


Notes to editor: 

SEPA’s work across LEZs 

  • SEPA worked in close partnership with councils and Transport Scotland, collated local traffic and emissions data to generate scientifically robust air quality models.  
  • SEPA presented the data using novel analysis and visualisation tools to enable local authorities and councillors to make informed decisions on their proposed LEZs. 
  • SEPA generated data for bus operators to help promote investment in cleaner vehicles within their fleet. 
  • SEPA developed bespoke bus operator tools that allowed operators to route the cleanest buses along heavily polluted streets, thus maximising emissions reductions whilst improving local air quality. 


SEPA's air quality modelling predicts that the introduction of the LEZ, combined with the City Centre Masterplan interventions on Union Street, will see significant reductions in air pollutant emissions from vehicles within the city centre. SEPA will continue to work with stakeholders to monitor and report on the performance of the LEZ whilst ensuring the Aberdeen air quality model is kept up to date to reflect infrastructure changes in the future. 


SEPA developed modelling to predict changes in the pollutants associated with the introduction of the LEZ in the city. SEPA developed bespoke data analysis tools for councillors, providing evidence of the expected improvements in air quality. Working in partnership with the local authority’s traffic consultants, SEPA presented the evidence to city councillors on the scientific reasons for the preferred LEZ zones. SEPA is continuing to engage with the local authority on areas out with the LEZ areas to help to continue to improve air quality across the city.  


There were several LEZ options considered for Edinburgh, include a city-wide LEZ. SEPA undertook modelling for each LEZ option, providing the evidence for the local authorities to consider. SEPA’s Senior Air Modelling Scientist developed a series of bespoke tools to guide councillors through the implications of each option to help them make informed decisions on the most appropriate LEZ boundary to achieve air quality improvements. 


SEPA’s Senior Air Modelling Scientist provided Glasgow City Council with the evidence to support the implementation of Glasgow’s LEZ. To support the delivery of the first phase of Glasgow’s LEZ, SEPA developed bus-specific tools for the cities bus operators and Glasgow City Council, helping them to identify key routes that would benefit most from cleaner buses. 
SEPA will continue its partnership approach with the local authorities, Transport Scotland, commercial bus operators, and other stakeholder as it moves towards monitoring the performance of the LEZs to ensure the accelerated reductions in air pollution are met.  


Information about the announcement on LEZs by Transport Scotland can be found here: Low Emission Zones introduced across Scotland 

Air Quality  

SEPA has a number of roles when it comes to Scotland’s air quality. As well as regulating and monitoring emissions from certain industrial activities that can cause air pollution, SEPA:  

  • Provides advice and guidance to government, industry and the public on pollution control and other environmental issues;
  • Works with partners to understand and improve air quality;  
  • Provides information on emissions from regulated industries through the Scottish Pollutant Release Inventory (SPRI);  
  • Works with partners to understand and improve air quality, meeting Scottish and UK objectives set to address air quality, climate change and the trans-boundary impacts of air pollution. 

Further information about our work on air quality can be found here