Mike Ashmore



Mike was appointed to a chair in Environment in October 2004. His research work is divided between the Department and the Stockholm Environment Institute at York (SEIY), for whom he works 20% of his time. He also leads the York Centre for Atmosphere/Biosphere Exchange (YCABE), which is a joint initiative between Environment, SEIY, Biology and Chemistry. Prior to coming to York, he was Professor of Environmental Science at the University of Bradford, and from 1975 to 1998 worked as a research fellow, then lecturer and reader at Imperial College London.


Professor of Environmental Science University of York
Phd Leeds
BSc East Anglia



My research is focussed on the exposure and impacts of air pollutant. I have thirty years of experience of research on the impacts of pollution on vegetation, including work on agricultural crops, trees, grasslands, heathlands and insect pests. This research has involved chamber studies, field manipulation experiments, field surveys and modelling, and studies of the effects of a range of pollutants, including ozone, acid deposition, nitrogen oxides and ammonia. I have experience of the design and interpretation of field surveys of pollutant impacts, including use of biomonitors, application of chemical protectants and surveys of forest health and ground flora, and of  interpretation of changes in national distributions of lichens, bryophytes and vascular plants in the context of exposure to air pollution. 

In addition to this work on air pollution impacts on the natural environment, I have fifteen years experience of work on assessment of human exposure to air pollution. This research on personal exposure includes studies on CO, NO2 and particulates, in a range of locations, including Mexico City, Athens, Delhi, London, Bradford, Leicester, Northampton, and York. This involves both direct measurement of personal and indoor exposure, and the development and application of probabilistic models of indoor and personal exposure, designed to simulate individual and personal exposure. 

Policy Applications

My research is strongly focussed on the development of effective management of air pollution, primarily by improving the basis for evaluation of the ecological and health benefits of measures to control emissions to the atmosphere. In particular, I have been actively involved in the development of ecological risk assessment based on the critical load and critical level approach, especially for nitrogen deposition, for ozone, and for heavy metals, and its application in the UK and Europe. I work actively in providing scientific advice to a range of bodies, but especially to the UK Department for Environment Food and Rural Affairs (Defra) and within the UN/ECE Conventional on Transboundary Air Pollution (CLRTAP). My work within the Atmospheric Environment group of SEIY is also involved with assessment of impacts of air pollution in Asia and Africa, and global risk assessments for ozone and nitrogen deposition.  


Much of my research is inter-disciplinary and involves research collaborations with a range of other universities and research institutes. At present, I am involved collaborative projects on:- developing flux-based methods for assessing ozone impacts across Europe, assessing the impacts of reduced and oxidised nitrogen deposition, developing and applying critical load methods for metals in soils and freshwaters in the UK, determining the impact of ozone of fluxes of methane and carbon dioxide, assessing the impacts of ozone on upland ecosystems, and modelling personal exposure to air pollution in large office buildings.


2008-2011 NERC £354k

with Sylvia Toet (Environment), Phil Ineson and Thorun Helgasson (Biology), University of Newcastle and Centre for Ecology and Hydrology

There is evidence that global background ozone levels are increasing, and it is known that ozone has the potential to alter carbon uptake by vegetation. However, the potential for ozone to alter carbon dioxide and methane fluxes from soils is much less certain, even though it could be an important feedback in global climate change.   This project involves investigations of the effects of ozone on methane and carbon dioxide fluxes in wetland mesocosms and a grassland community using experimental facilities in the Tyne valley. As well as direct measurements of fluxes of carbon dioxide and methane, detailed studies will be made on changes in microbial communities using advanced molecular methods.   

2007-2012 Open Air Laboratories (OPAL) (Big Lottery Fund £350k

with Carolyn Snell (Social Policy), Steve Cinderby (SEIY), and Piran White and Pierre Delmelle (Environment)

This award is part of a major national project, involving sixteen universities and research organisation, with funding of £11.9 million. OPAL is an England-wide initiative designed to inspire and support communities to explore, study enjoy and protect their local environment. Our role will be to co-ordinate the work in the Yorkshire and Humberside region, focussing on working in four deprived communities to map the local environment, focussing on air and soil pollution and biodiversity, through the use of participatory GIS. We will also collaborate in the delivery of five national projects, on air, soils, water, biodiversity and climate. 

2007-2010 NERC £323k

Ecological effects of reduced versus oxidised nitrogen deposition; with Leon van den Berg and Malcolm Cresser (Environment), Centre for Ecology and Hydrology and Alterra, Netherlands.

Current critical loads and risk assessment for the effects of nitrogen deposition on sensitive plant communities is based on total nitrogen deposition. However, reduced and oxidised nitrogen deposition have quite different sources and quite different effects. In this project we test the hypothesis that on acid soils in particular, the impacts of reduced nitrogen deposition will be greater than that of oxidised nitrogen deposition. The work involves a mesocosm experiment at York, a field experiment south of Edinburgh and analysis of records of vegetation change in both the Netherlands and the UK.

2007-2010 DEFRA £169k

Modelling of ozone flux and deposition (With Lisa Emberson, SEI).

This contract aims to further develop the application of flux-based risk assessment for ozone, an approach for which we have played a pioneering role. The work aims to further develop model approaches and parameterisation for phenology and soil water deficit, especially for forest ecosystems, and to develop methods to apply flux-based risk assessment to species mixtures, focussing in particular on grassland ecosystems.

2006-2007 Joint Nature Conservation Committee £13k

Impacts of ozone on nature conservation

This review contract aimed to summarise and evaluate the evidence for effects of ozone on communities of high conservation value. In particular, it identified priority species and habitats in the UK that might be at greatest risk of adverse effects of ozone. 

2006-2007 DEFRA £74k 2006-2009 Effects of ozone on upland vegetation; with Sylvia Toet (Environment), University of Lancaster, University of Newcastle, and Centre for Ecology and Hydrology.
This project supports a PhD student to work as part of a wider experimental project on the impacts of ozone. We contribute to a long-term experiment in the upper Tyne valley in which an upland grassland community managed to increase biodiversity is subjected to increased ozone concentrations in situ. This is the first such field experiment in the UK, and one of very few field experiments on semi-natural ecosystems in the world. We also are studying responses of wetland mesocosms to ozone in a chamber experiment at Newcastle University. 
2006-2010 Home Office £167k

Indoor Air Quality and Personal Exposure; with Building Research Establishment

This project aims to model the personal exposure of office workers to air pollutants, focussing on nitrogen dioxide, carbon monoxide and particulates. It combines a detailed measurement campaign in different offices within a large building with development and testing of a model to predict the concentrations of pollutants in different types of office and hence the frequency distribution of personal exposures of the building occupants. 

2004-2007 DEFRA £314k

Critical loads of metal deposition; with Centre for Ecology and Hydrology

This project aims to develop and apply new approaches to assessing the critical loads for deposition of lead, cadmium, copper and zinc in the UK, and to contribute to critical load-based risk assessment for metal deposition within Europe. Particular emphasis is placed on development of dynamic models to assess the timescales of ecosystem response to changes in metal deposition.

2004-2007 DEFRA £61k

Impacts of nitrogen deposition; with Kevin Hicks (SEIY)

This project was part of a much larger national programme investigating the impacts of nitrogen deposition. The work undertaken related to determining whether long-term changes in the species composition of calcareous grasslands were related to nitrogen deposition, developing methods of assessing site-specific critical loads, and modelling the impacts of nitrogen deposition and management on heathlands over the last century. 

2004-2007 NERC £142k

Tropsopheric ozone pollution: using stable isotopes; with Phil Ineson (Biology), Lisa Emberson (SEIY), University of Bristol and University of Newcastle.

This recently completed project investigated the use of stable isotopes to enhance our understanding of the deposition, pathways and fate of ozone in plants and soils. We succeeded for the first time in developing new methods to generate 18O labelled ozone with an activity which was high enough to allow us to trace the fate of ozone and environmentally realistic concentrations. The project has provided important new insights into the fate of 18O3 within plants and leaves, and the effects of pre-exposure with ozone in modifying the fate of ozone within leaves.


Current students

  • Rebecca Keelan. Effects of ozone on plant communities of the Yorkshire Dales
  • Nauman Mohmmed. Effects of air pollution on crop quality in Pakistan (with Lisa Emberson)
  • Julie Simon National and international policy development for ozone (with John Forrester, SEIY)  
  • Wendy Song. Person exposure to particulate air pollution in buses.
  • Kerstin Wedlich Impacts of ozone on upland ecosystems (with Sylvia Toet)

Recent Students

  • Mahmoud Mahammadyan. Personal exposure to PM2.5.
  • Hamid Behroozi. Monitoring metal exposure through ICP-MS/LA analysis of hair
  • Ben Haworth. Impacts of nitrogen deposition on lichens and bryophytes.
  • Felicity Hayes. Ozone impacts on grassland species (with Gina Mills)
  • Saleh Khayar. Air pollution in an industrial Saudi city.

External activities


  • Ad-hoc member of Defra Air Quality Expert Group
  • Member of steering committee of the UK Committee on Air Pollution Effects Research
  • Member of steering committee of CLRTAP Integrated Co-operative Programme on Vegetation
  • Member of CLRTAP expert panel on critical loads for metals
  • Member of Royal Society surface ozone working group
  • Member of Defra National Expert Group on Transboundary Air Pollution
  • Advisor to World Health Organisation on revised air quality guidelines (reviewer of chapter on human exposure).
  • Co-author ‘Air’ chapter of UNEP Global Environmental Outlook 4.
  • I have also been a member of past UK Government advisory groups, including Defra National Expert Group on Transboundary Air Pollution, Department of the Environment Photooxidant Review Group, Department of the Environment Critical Loads Advisory Group, and Department of Health Advisory Group on the Medical Aspects of Air Pollution Episodes

Editorial duties

  • 1996-, Editorial board, Imperial College Press series of Air Pollution Reviews
  • Lead editor, Special Issue of Atmospheric Environment on 'New Issues in Risk Assessment for Ozone'
Ashmore, Mike

Contact details

Prof. Mike Ashmore
Environment Department
University of York
Room V/X/225 (Grimston House)
YO10 5DD

Tel: 01904 324744
Fax: 01904 322998



Other teaching

Course Leader

  • MSc Environment Science and Management

Module Leader

  • Climate Change and Carbon Management
  • Environmental Science and Management Case Studies
  • Environmental Monitoring and Analysis
  • Environmental Monitoring and Assessment 

Contributor to

  • Climate Change
  • Current Topics in Environmental Science
  • Environmental Contaminants: Pathways and Impacts
  • Pollution Effects on Plant/Soil/Water Systems