Imperial College London


Faculty of MedicineSchool of Public Health

Senior Lecturer in Environmental Health



h.walton Website




Building E - Sir Michael UrenWhite City Campus





Dr Heather Walton specializes in air pollution health impact assessment.  She was involved in the benefits analysis for the cost benefit analysis of the UK National Air Quality Strategy 2007, has worked on quantification of health benefits for the UK Committee on the Medical Effects of Air Pollutants (COMEAP) since 1996 and is now Chair of the COMEAP sub-group on Quantification of Air Pollution Risk (QUARK).  She was an invited expert for both the WHO projects ‘Review of the Health Aspects of Air Pollution’ and on ‘Health Risks of Air Pollution in Europe’ which set concentration-response functions for cost-benefit analysis of policies in Europe.  She has published reports on the health benefits of air pollution alert services, the health burden of air pollution in London, the air pollution and health benefits of different routes to meeting greenhouse gas emissions targets and developing methods to estimate fine scale exposure to nitrogen dioxide for the purpose of quantification across Europe.  She previously worked on air pollution in the scientific civil service, ensuring scientific evidence on air pollution and health was appropriately communicated to those developing policy.


Key Leadership Roles:

NIHR Health Protection Research Unit on Environmental Exposures and Health Co-Lead Theme II Air Pollution and Health

Chair Committee on the Medical Effects of Air Pollutants sub-group on Quantification of Air Pollution Risk

Key Research Interests:

Heather has a strong interest in the application of science to the optimization of policy on air pollution and health. A biochemist by training, Heather subsequently trained in toxicology. She worked as a scientific civil servant for many years at the Department of Health and the Health Protection Agency, writing review papers and reports for Expert Committees such as the Committee on the Medical Effects of Air Pollutants (COMEAP); developing calls for research proposals for the Department of Health and providing scientific advice on air pollution and health to Defra. Her particular interests at include the health effects of ozone, distinguishing the effects of nitrogen dioxide from those of particles, health impact assessment, systematic reviews of the evidence on air pollution and health and the use of life-tables to assess the effects of long-term exposure to particles.  

Research Collaboration:

Extensive research collaborations both within the Environmental Research Group, the Department of Epidemiology and Biostatics and the Centre for Environmental Policy at Imperial and beyond, including with Public Health England; Climate Change Committee Secretariat; Clinical Pharmacology, St. Thomas’s Hospital; MRC Toxicology Unit, Cambridge; EMRC and Paul Watkiss Associates (environmental economists); Impact and Engagement Services, King’s College London; Population Health Institute, St. George;s, University of London; Oxford University, Centre for the Environment; Department of Epidemiology and Biostatistics, University of Athens; US Health Effects Institute; Harvard T.H. Chan School of Public Health.

Post-doctoral fellows under Supervision:

Dr Dimitris Evangelopoulos



Gowers AM, Walton H, Exley KS, et al., 2020, Using epidemiology to estimate the impact and burden of exposure to air pollutants, Philosophical Transactions of the Royal Society A-mathematical Physical and Engineering Sciences, Vol:378, ISSN:1364-503X

Evangelopoulos D, Perez-Velasco R, Walton H, et al., 2020, The role of burden of disease assessment in tracking progress towards achieving WHO global air quality guidelines., Int J Public Health

Floyd CN, Shahed F, Ukah F, et al., 2020, Acute Blood Pressure-Lowering Effects of Nitrogen Dioxide Exposure From Domestic Gas Cooking Via Elevation of Plasma Nitrite Concentration in Healthy Individuals, Circulation Research, Vol:127, ISSN:0009-7330, Pages:847-848

Evangelopoulos D, Katsouyanni K, Keogh RH, et al., 2020, PM2.5 and NO2 exposure errors using proxy measures, including derived personal exposure from outdoor sources: A systematic review and meta-analysis., Environ Int, Vol:137

D'Antoni D, Auyeung V, Walton H, et al., 2019, The effect of evidence and theory-based health advice accompanying smartphone air quality alerts on adherence to preventative recommendations during poor air quality days, A Randomised Controlled Trial, Vol:124, ISSN:0160-4120, Pages:216-235

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