Project Highlights:

  • Develop new skills in air pollution emissions measurement and modelling
  • Generate new knowledge on how emissions from vehicle tailpipes in realistic driving conditions impact the urban atmospheric environment
  • Learn from industry and local government partners while conducting research that will improve our ability to manage air quality


Air pollution is a major problem globally, with ambient (outdoor) air pollution estimated by the World Health Organization to cause 4.2 million premature deaths per year. In urban areas vehicle emissions are a or the major source of air pollution, and strategies for reducing traffic and promoting appropriate technologies are needed, but these strategies require robust data on current and future vehicle emissions.

Despite improvements in vehicle engine technology, traffic exhaust emissions have large uncertainties, due in large part to the differences between laboratory and real world performance of vehicles. In 2017, new European regulations required every new vehicle undergo the Worldwide Harmonised Light Vehicle Test Procedure (WLTP) in the laboratory, and by 2019, all new vehicles will additionally be required to undergo Real Driving Emissions (RDE) tests as well, with Portable Emissions Measurement System (PEMS) monitors tracking emissions over 90 miles of different driving conditions. While these tests will provide major improvements, the emissions at the end of the day will be specified by a single average number for each pollutant (for example g/km). Therefore there are likely to remain to be large uncertainties in urban emissions inventories that can only be reduced by understanding how emissions production depends for example on traffic flow, topography, and hybrid engine operation mode. Figure 1. shows an example of how nitrogen oxides (NOx) emissions vary profoundly along an urban driving route.

This PhD will develop a fleet emissions model toolkit, underpinned by experimental validation, that can be used to produce improved urban emissions inventories by integrating location specific information on roads and traffic patterns with knowledge on engine mode-dependence on emissions and NOx/PM ratio for contemporary hybrid and ICE vehicles. This model toolkit will make it possible for policymakers and local authorities to have a much clearer understanding of how traffic flow regulation and fleet change incentive strategies can reduce environmental and human health impacts of urban air pollution. Additionally, this model toolkit will be able to evaluate which vehicle types are most appropriate for which journey types in an urban landscape to minimize environmental impact and human exposure to air pollution.

Figure 1: NOx emissions in grams per kilometre travelled measured on real journeys in Central London using ultra-fast onboard gas analysers, with higher levels typically corresponding to transient acceleration; image reproduced from Irwin et al., 2018.


A real-world emissions measurement experiment conducted in partnership with industry will provide critical understanding for the student to be used in modelling. These results will be compared with the Ricardo WAVE combustion and emissions model outputs for the same vehicles. A modelling toolkit will be developed to incorporate WAVE-type calculations with local information on traffic composition and flows. Emissions will be modelled in selected small (e.g. 1km) busy urban areas for NOx and particulate matter 2.5 microns and smaller (PM2.5) for a realistic fleet composed using the average emissions rates per km for the vehicles and traffic data provided by Leicestershire County Council. This will be compared with the tailpipe emissions inventory for the area. Importantly, the research will be conducted with the aim of providing evidence policymakers and automotive manufactures can use to consider trade-offs between fuel efficiency and air pollution emissions in densely populated urban environments.


Training and Skills

The University of Leicester offers training on a wide range of technical topics including high performance computing, as well as courses on research methods and communication. The student will have access to degree and masters modules including environmental science and GIS. Hands-on training in emissions measurement will be provided by industrial partners. Additionally, the student will have access to training and workshops related to engine and emissions technology from leading engineering schools at Loughborough University. While the focus of the PhD is environmental science, in depth understanding of hybrid and ICE engine performance is critical to conducting the research.


Year 1: Exisiting vehicle air pollution inventories and traffic emissions modelling approaches will be reviewed. A sample of vehicle emissions across engine types will be measured in real world driving conditions using high resolution portable emissions montoring systems, to generate example data and provide fundamental training in engine emissions measurement and interpretation.

Year 2: A modelling toolkit will be developed for a local area selecting a sub-sample of vehicle and engine types to model real world NOx and PM2.5 emissions in detail. The modelling will incorporate emissions data collected during the PhD, as well as a much larger dataset supplied industrial partners.

Year 3: The modelling toolkit will be applied to generate evidence for local policy decisions on fleet composition and traffic regulation, assign trips of different purposes in the region of interest to the most appropriate vehicle for that trip, and evaluate uncertainties in the local emissions inventory.

Throughout the project, the student will engage regularly with industrial and governmental partners, to ensure that the best input data are selected and the most relevant evidence produced.

Partners and collaboration (including CASE)

Horiba-MIRA, Nuneaton, is the proposed CASE partner, providing access to and expertise in the use of their new 8 Million GBP Advanced Emissions Test Centre which includes both WLTP and RDE emissions testing capability. Additionally the PI proposes to extend an existing partnership with Leicester City Council and Leicestershire County Council on transport, working with them to incorporate traffic data. A unique approach for this PhD is the joint supervision from Loughborough University, which will ensure the student delivers to the NERC science based the best emission information and approaches from automotive emissions perspective.

Further Details

For further information please contact Dr. Joshua Vande Hey, jvh7@le.ac.uk . Learn more about Dr. Vande Hey’s work here:


And Dr. Spencer’s work here:


Contacting the lead supervisor Dr. Vande Hey at jvh7@le.ac.uk prior to applying is highly encouraged.