Ailish Graham

Ailish Graham


PhD Simulation and evaluation of regional rural air quality in the UK.

Supervised by Jim McQuaid, Kirsty Pringle, Steve Arnold and Richard Pope

Air quality is a major issue affecting the majority of the global population. Traditionally air quality studies have focussed on urban areas, where pollutant loadings are high and local sources (e.g. traffic) play a significant role in the total burden. This is reflected in the comprehensive network of observations that exist in urban areas; these urban monitoring sites are generally situated to target exceedences of air quality levels, and are deliberately placed in the most polluted locations (e.g. kerbside). Rural areas can also be affected by air pollution, but as they are seen as “clean” areas, they have been the subject of much less research. It is known that rural air pollution is controlled by a complex mix of international, regional and local sources, but as very few rural observations exist air quality models are poorly constrained in this regime. There are also additional sources of air pollution that affect rural areas more than urban ones, for example agricultural emissions play an important role in forming rural PM, but are less regulated than industrial emissions, and reductions have been far smaller over the past 30 years. As urban air quality improves, it may be the case that exposure in rural areas becomes increasingly important contributor to overall exposure.

My PhD has been broken down into three key sections:

  1.     ‘Impact of weather types on UK ambient particulate matter concentrations’. Atmospheric Environment (accepted) 

Investigating the the relative contributions of local emissions and long-range transport to PM2.5 concentrations under different weather types. We use observations of PM2.5 from urban background observational sites from the AURN network alongside an atmospheric chemistry transport model (EMEP4UK) alongside lamb weather types (LWT) to assess how different weather types affect PM2.5 concentrations. We also develop a model for calculating the summed emissions of air masses reaching each of the observational sites using the ROTRAJ back trajectory model with a gridded bottom-up emission inventory. This allows us to examine the relative contribution of emissions from inside and outside of the UK to the total summed emissions within air masses arriving at each of the observational sites. We can also use the magnitude of these summed emissions as a tracer for how polluted each air mass is. These are binned by LWT to assess which wind directions are associated with the most polluted air masses and the contribution of long-range transport to the summed emissions.

  1. a)   The impact of the Saddleworth Moor Fires in 2018 on Air Quality 

The June 2018 Saddleworth Moor fires were some of the largest UK wildfires on record and lasted for approximately three weeks. They emitted large quantities of smoke, trace gases and aerosols which were transported downwind over the highly populated regions of Manchester and Liverpool. We use observational data from the UK AURN network (PM2.5), state-of-the-art satellite measurements from TROPOMI (total column CO and NO2) and measurements from the FAAM aircraft campaign (CO, NO2 and O3). Observations indicate the fires had a substantial impact on AQ at the surface and throughout the boundary layer, emitted high concentrations of pollutants but also forming secondary pollutants such as O3 downstream as the plume aged. 

2. b)  The impact of the Saddleworth Moor fires on PM2.5 Air Quality and Health using the WRF-Chem model at 10 km resolution.

Following on from the observational work we ran the WRF-Chem model over the region for the fire period at 10 km in order to investigate the air quality and health impacts of the fires. Since the fires are some of the largest in the UK and the first close to a large population, this provides a good case-study for the impact of fires in the UK on the population. We find that the fires had a substantial impact on AQ in the region. PM2.5 concentrations increased by > 300% in Oldham and Manchester and up to 50% in Liverpool, Wigan and Warrington (~80 km away). This led to a third of the population (4.7 million people) in the simulation domain being exposed to moderate PM2.5 concentrations on at least one day according to the Daily Air Quality Index (36-53 μg m-3), between June 23rd-30th 2018. This equates to 4.5 million people being exposed to PM2.5 above the WHO 24-hour safe-limit exposure (25 μg m-3) on at least one day. Using a concentration-response function we calculate the short-term health impact, which indicates that up to 60% of excess mortality between June 23rd-30th 2018 was attributable to the fires. This represents up to a 148% increase in excess mortality across the region compared if there were no fires.

  1. My final piece of work aims to look at either:
    The impact of reductions in the legal limit for PM2.5 on health using WRF-Chem at high resolution (~6 km) or the impact of reductions in ammonia in the UK and the rest of Europe on PM2.5 concentrations in the UK. 


  • Pope RJ, Graham AM, Chipperfield MP, Veefkind JP. High resolution satellite observations give new view of UK air quality. Weather. 74(9), pp. 316-320. DOI: 10.1002/wea.3441, 2019.
  • Graham AM, Pringle K, Arnold SR, Pope RJ, Vieno MI, Butt E, Conibear LA, Stirling EL, McQuaid JB. Impact of weather types on UK ambient particulate matter concentrations. Atmospheric Environment. (accepted, in press). 
  • Graham AM, Pope RJ, McQuaid JB, Arnold SR, Bruno AG, Moore DP, Harrison JJ, Chipperfield MP, Rigby R, Lee, J, Wilde, S. Impact    of the June 2018 Saddleworth Moor wildfires on air quality in northern England, Environmental Research Communications. (accepted with revisions). 
  • Stirling EL, Pope RJ, Graham AM, Chipperfield MP, Arnold SR. Quantifying the Transboundary Contribution of Nitrogen Oxides to UK Air Quality. Atmospheric Science Letters. (accepted with revisions).
  • Graham AM, Pope RJ, Pringle K, Arnold SR, Chipperfield MP, Conibear LA, Butt EW, Kiely L, Knote C, McQuaid JB. Substantial degradation in Air Quality due to Saddleworth Moor Wildfire. (submitted to Environmental Research Letters)

Demonstrating: I demonstrate on the “SOEE3431 Atmospheric Pollution: Causes, Impact and Regulation” module. Students use an ozone box model to investigate the complex, non-linear relationship of ozone with precursor emissions in different environments. 

Supervision: Co-supervision of two undergraduate students during their dissertation projects in Leeds. Both used observational and satellite data to study UK NO2. One received an award for her work on continental European contribution to NO2 concentrations in three UK cities and has since gone onto publish her work. The student I currently co-supervise is carrying out valuable research deriving top-down emissions of UK NOx from the TROPOMI satellite. This work will contribute to work funded by DEFRA, aiming to verify official bottom-up inventories for the UK using satellites.  


  • The Royal Society: Air Quality: past, present and future – poster presentation
  • European Aerosols Conference – poster presentation
  • NCAS Air Quality Conference 2018 and 2019 – oral presentations
  • ICAS Annual Science Meeting (ASM) – poster presentation 


  • Most significant scientific discovery – ICAS ASM


  • I appeared on BBC’s ‘inside out’ to talk about the impacts of the Saddleworth Moor fires on air quality in 2018.
  • I have developed a good relationship with Leeds city council, attending meetings on the clean air zone and public health.
  • I have collaborated with Natural England’s peat pilot to use evidence from my work to inform policy decisions on peatland management in the Greater Manchester region. 

Previous Education

MRes Climate and Atmospheric Science, University of Leeds - 2016
Dissertation: 'Characterising the structure of the East Asian Summer Monsoon' as part of the Met Office Climate Science for Partnership China (CSSP) project. Supervised by Dr Cathryn Birch.

Modules: Climate Change: Science and Impacts, Atmosphere and Ocean Climate Change Processes, Atmosphere of Planet Earth, Meteorology, Atmospheric PhysicsBSc Geological

My master’s project used the extensive radiosonde network in China to examine the thermodynamic properties of the monsoon both from a lagrangian and eularian perspective. This formed part of the larger Climate Science for Service Partnership for China with the Met Office. I was invited to give an oral presentation on my results at the Met Office to lead scientists within the project. The work is now being used by a postdoc in Leeds to form a paper.

Oceanography, Bangor University - 2014
Dissertation: 'Simulation of the impacts of a partial and complete East Antacrtic Ice Sheet collapse on the drivers of the Indian Summer Monsoon'. Supervised by Dr Mattias Green

I used a multi-layer ocean model to simulate the impact of a partial and full collapse of the East Antarctic Ice Sheet on oceanic variables such as sea surface temperature and evaporation. By comparing these results to a ‘control’ run with no collapse of the ice sheet I could explore the impacts.

Modules: Estuary and Sea Shelf Processes, Earth and Ocean Observation, Tides, Waves and Sampling, Prince Madog Cruise, Ice and Oceans, Coastal Water Processes, Sediment Dynamics, Coastal Sediments Field Study, Marine Sediment Environments and Palaeoceanography.

Research interests

I'm a PhD student in the Institute for Climate and Atmospheric Science and a member of the Atmospheric Chemistry and Aerosols research group

My main reserach interests are:

•    The relationship between emissions and meteorology and their impact on regional air quality (AQ). 
•    Atmospheric modelling of air pollutants (e.g. PM2.5, O3 and NO2) and their use in understanding non-linear relationships between primary and secondary pollutants. 
•    UK AQ and its impact on population exposure (e.g. the 2018 Saddleworth Moor fires, the impact of changes in emissions). 
•    The impact of weather regimes on observed/modelled AQ. 



  • MRes, Climate and Atmospheric Science, University of Leeds
  • BSc, Geological Oceanography, Bangor University

Research groups and institutes

  • Atmospheric Chemistry and Aerosols
  • Institute for Climate and Atmospheric Science