Imperial College London

DrTimOxley

Faculty of Natural SciencesCentre for Environmental Policy

Research Fellow
 
 
 
//

Contact

 

+44 (0)20 7594 9297t.oxley Website

 
 
//

Location

 

305Weeks BuildingSouth Kensington Campus

//

Summary

 

Publications

Publication Type
Year
to

39 results found

ApSimon H, Oxley T, Woodward H, Mehlig D, Holland M, Reeves Set al., 2023, Integrated assessment modelling of future air quality in the UK to 2050, and synergies with net-zero strategies, Atmosphere, Vol: 14, Pages: 1-21, ISSN: 2073-4433

Integrated assessment modelling (IAM) has been successfully used in the development of international agreements to reduce transboundary pollution in Europe, based on the GAINS model of IIASA. At a national level in the UK, a similar approach has been taken with the UK Integrated Assessment Model, UKIAM, superimposing pollution abatement measures and behavioural change on energy projections designed to meet targets set for the reduction of greenhouse gas emissions and allowing for natural and imported contributions from other countries and shipping. This paper describes how the UKIAM was used in the development of proposed targets for the reduction of fine particulate PM2.5 in the UK Environment Act, exploring scenarios encompassing different levels of ambition in reducing the emissions of air pollutants up to 2050, with associated health and other environmental benefits. There are two PM2.5 targets, an annual mean concentration target setting a maximum concentration to be reached by a future year, and a population exposure reduction target with benefits for health across the whole population. The work goes further, also demonstrating links to social deprivation. There is a strong connection between climate measures aimed at reducing net GHG emissions to zero by 2050 and future air quality, which may be positive or negative, as illustrated by sectoral studies for road transport where electrification of the fleet needs to match the evolution of energy production, and for domestic heating, where the use of wood for heating is an air quality issue. The UKIAM has been validated against air pollution measurements and other types of modelling, but there are many uncertainties, including future energy projections.

Journal article

Oxley T, Vieno M, Woodward H, ApSimon HM, Mehlig D, Beck R, Nemitz E, Reis Set al., 2023, Reduced-form and complex Actm modelling for air quality policy development: a model inter-comparison, Environment International, Vol: 171, Pages: 1-13, ISSN: 0160-4120

Simulation models can be valuable tools in supporting development of air pollution policy. However, exploration of future scenarios depends on reliable and robust modelling to provide confidence in outcomes which cannot be tested against measurements. Here we focus on the UK Integrated Assessment Model, a fast reduced-form model with a purpose to support policy development with modelling of multiple alternative future scenarios, and the EMEP4UK model which is a complex Eulerian Atmospheric Chemistry Transport Model requiring significant computing resources. The EMEP4UK model has been used to model selected core scenarios to compare with UKIAM, and to investigate sensitivity studies such as the interannual variability in response to meteorological differences between years. This model intercomparison addresses total PM2.5, primary PM2.5 and Secondary Inorganic Aerosol concentrations for a baseline of 2018 and selected scenarios for projections to 2040. This work has confirmed the robustness of the UK Integrated Assessment Model for assessing alternative futures through a direct comparison with EMEP4UK. Both models have shown good agreement with measurements, and EMEP4UK shows an ability to replicate past trends. These comparisons highlight how a combination of reduced-form modelling (UKIAM) and complex chemical transport modelling (EMEP4UK) can be effectively used in support of air pollution policy development, informing understanding of projected futures in the context of emerging evidence and uncertainties.

Journal article

Woodward H, Oxley T, Rowe EC, Dore AJ, ApSimon Het al., 2022, An exceedance score for the assessment of the impact of nitrogen deposition on habitats in the UK, Environmental Modelling and Software, Vol: 150, Pages: 1-11, ISSN: 1364-8152

Large areas of nitrogen-sensitive habitats are currently estimated to be in exceedance of their critical loads (CLs) as indicators for protection from nitrogen deposition. In the UK, deposition estimates from the semi-empirical Concentration Based Estimated Deposition (CBED) model are used for official reporting of current exceedances. The UK Integrated Assessment Model (UKIAM) framework is designed to provide future projections of concentrations and deposition due to projected changes in emissions. UKIAM has been extended to provide alternative deposition estimates aligned with those of CBED, and the results combined with the range in habitat CL values to create an exceedance score, leading to a probabilistic evaluation of CL exceedances. The utility of the method is demonstrated by analysing a series of hypothetical scenarios. It is shown that NH3 mitigation is likely to be four times more effective in reducing CL exceedances in the UK than the mitigation of NOx emissions.

Journal article

Mehlig D, 2021, Electrification of road transport and the impacts on air quality and health in the UK, Atmosphere, Vol: 12, Pages: 1-15, ISSN: 2073-4433

Currently, many cities in Europe are affected by concentrations of PM2.5 and NO2 above the WHO guidelines on the protection of human health. This is a global problem in which the growth of road transport constitutes a major factor. Looking to the future, electric vehicles (EVs) are considered to be the choice technology for reducing road transport greenhouse gas emissions, but their impact on air quality needs to be considered. Taking the UK as a case study, this paper begins by understanding the trajectory of a future scenario without the introduction of EVs, reflecting on the latest emission control improvements in internal combustion engine vehicles (ICEVs). This is then compared to a 2050 scenario in which the introduction of EVs, based on the UK government’s Transport Decarbonisation Plan, is reviewed. This plan includes a ban on the sale of ICEV cars and LGVs, beginning in 2030, with the subsequent electrification of heavier vehicles. By 2030, population exposure to NOx was found to be significantly reduced in the ICEV scenario, with a marginal further reduction found for the EV scenario. The EV scenario further reduced NOx exposure by 2050, with most of the benefits being realized before 2040. For the ICEV and EV scenario, PM2.5 emissions were largely unchanged due to the primary contribution of non-exhaust emissions, suggesting that EVs are likely to yield relatively smaller changes in exposure to PM2.5 than for NOx.

Journal article

ApSimon H, Oxley T, Woodward H, Mehlig D, Dore A, Holland Met al., 2021, The UK Integrated Assessment Model for source apportionment and air pollution policy applications to PM2.5, Environment International, Vol: 153, ISSN: 0160-4120

Source apportionment and the effect of reducing individual sources is important input for the development of strategies to address air pollution. The UK Integrated Assessment Model, UKIAM, has been developed for this purpose as a flexible framework, combining information from different atmospheric dispersion models to cover different pollutant contributions, and span the range from European to local scale. In this paper we describe the UKIAM as developed for SO2, NOx, NH3, PM2.5 and VOCs. We illustrate its versatility and application with assessment of current PM2.5 concentrations and exposure of the UK population, as a case-study that has been used as the starting point to investigate potential improvement towards attainment of the WHO guideline of 10 µg/m3.

Journal article

O'Driscoll R, Stettler MEJ, Molden N, Oxley T, ApSimon HMet al., 2017, Real world CO2 and NOx emissions from 149 Euro 5 and 6 diesel, gasoline and hybrid passenger cars, Science of the Total Environment, Vol: 621, Pages: 282-290, ISSN: 0048-9697

In this study CO2 and NOx emissions from 149 Euro 5 and 6 diesel, gasoline and hybrid passenger cars were compared using a Portable Emissions Measurement System (PEMS). The models sampled accounted for 56% of all passenger cars sold in Europe in 2016. We found gasoline vehicles had CO2 emissions 13-66% higher than diesel. During urban driving, the average CO2 emission factor was 210.5 (sd. 47) gkm-1 for gasoline and 170.2 (sd. 34) gkm-1 for diesel. Half the gasoline vehicles tested were Gasoline Direct Injection (GDI). Euro 6 GDI engines <1.4ℓ delivered ~17% CO2 reduction compared to Port Fuel Injection (PFI). Gasoline vehicles delivered an 86-96% reduction in NOx emissions compared to diesel cars. The average urban NOx emission from Euro 6 diesel vehicles 0.44 (sd. 0.44) gkm-1 was 11 times higher than for gasoline 0.04 (sd. 0.04) gkm-1. We also analysed two gasoline-electric hybrids which out-performed both gasoline and diesel for NOx and CO2. We conclude action is required to mitigate the public health risk created by excessive NOx emissions from modern diesel vehicles. Replacing diesel with gasoline would incur a substantial CO2 penalty, however greater uptake of hybrid vehicles would likely reduce both CO2 and NOx emissions. Discrimination of vehicles on the basis of Euro standard is arbitrary and incentives should promote vehicles with the lowest real-world emissions of both NOx and CO2.

Journal article

Reis S, Voigt K, Oxley T, 2017, Thematic issue on modelling human and ecological health risks, ENVIRONMENTAL MODELLING & SOFTWARE, Vol: 93, Pages: 106-108, ISSN: 1364-8152

Journal article

O'Driscoll R, ApSimon H, Oxley T, Molden N, Stettler M, Thiyagarajah Aet al., 2016, A portable emissions measurement system (PEMS) study of NOx and primary NO2 emissions from Euro 6 diesel passenger cars and comparison with COPERT emission factors, Atmospheric Environment, Vol: 145, Pages: 81-91, ISSN: 1352-2310

Real world emissions of oxides of nitrogen (NOx) often greatly exceed those achieved in the laboratory based type approval process. In this paper the real world emissions from a substantial sample of the latest Euro 6 diesel passenger cars are presented with a focus on NOx and primary NO2. Portable Emissions Measurement System (PEMS) data is analysed from 39 Euro 6 diesel passenger cars over a test route comprised of urban and motorway sections. The sample includes vehicles installed with exhaust gas recirculation (EGR), lean NOx traps (LNT), or selective catalytic reduction (SCR). The results show wide variability in NOx emissions from 1 – 22 times the type approval limit. The average NOx emission, 0.36 (sd. 0.36) g km-1, is 4.5 times the Euro 6 limit. The average fraction primary NO2 (fNO2) is 44 (sd. 20) %. Higher emissions during the urban section of the route are attributed to an increased number of acceleration events. Comparisons between PEMS measurements and COPERT speed dependent emissions factors show PEMS measurements to be on average 1.6 times higher than COPERT estimates for NOx and 2.5 times for NO2. However, by removing the 5 most polluting vehicles average emissions were reduced considerably.

Journal article

Dore A, Reis S, Oxley T, ApSimon H, Hall J, Vieno M, Kryza M, Green C, Tsagatakis I, Tang S, Braban C, Sutton Met al., 2016, Calculation of Source-Receptor Matrices for Use in an Integrated Assessment Model and Assessment of Impacts on Natural Ecosystems, 34th International Technical Meeting on Air Pollution Modelling and its Application (ITM), Publisher: SPRINGER-VERLAG BERLIN, Pages: 107-112

Conference paper

Dore A, Reis S, Oxley T, ApSimon H, Hall J, Vieno M, Kryza M, Green C, Tsagatakis I, Tang S, Braban C, Sutton Met al., 2016, Calculation of Source-Receptor Matrices for Use in an Integrated Assessment Model and Assessment of Impacts on Natural Ecosystems, 34th International Technical Meeting on Air Pollution Modelling and its Application (ITM), Publisher: SPRINGER INT PUBLISHING AG, Pages: 107-112

Conference paper

Oxley T, ApSimon HM, de Nazelle A, 2015, Investigating the sensitivity of health benefits to focussed PM<sub>2.5</sub> emission abatement strategies, ENVIRONMENTAL MODELLING & SOFTWARE, Vol: 74, Pages: 268-283, ISSN: 1364-8152

Journal article

Smith AC, Holland M, Korkeala O, Warmington J, Forster D, Apsimon H, Oxley T, Dickens R, Smith SMet al., 2015, Health and environmental co-benefits and conflicts of actions to meet UK carbon targets, Climate Policy, Vol: 16, Pages: 253-283, ISSN: 1752-7457

Journal article

Oxley T, Dore AJ, ApSimon H, Hall J, Kryza Met al., 2013, Modelling future impacts of air pollution using the multi-scale UK Integrated Assessment Model (UKIAM), ENVIRONMENT INTERNATIONAL, Vol: 61, Pages: 17-35, ISSN: 0160-4120

Journal article

Tzanidakis K, Oxley T, Cockerill T, ApSimon Het al., 2013, Illustrative national scale scenarios of environmental and human health impacts of Carbon Capture and Storage, ENVIRONMENT INTERNATIONAL, Vol: 56, Pages: 48-64, ISSN: 0160-4120

Journal article

Oxley T, ApSimon HM, Hall J, 2013, Application of a protectability index to assess habitat eutrophication in designated areas, 20th International Congress on Modelling and Simulation (MODSIM), Publisher: MODELLING & SIMULATION SOC AUSTRALIA & NEW ZEALAND INC, Pages: 1875-1881

Conference paper

Oxley T, de Nazelle A, Katara C, ApSimon HMet al., 2013, Bridging the gap between air pollution models and epidemiological studies, 20th International Congress on Modelling and Simulation (MODSIM), Publisher: MODELLING & SIMULATION SOC AUSTRALIA & NEW ZEALAND INC, Pages: 1882-1888

Conference paper

Oxley T, Elshkaki A, Kwiatkowski L, Castillo A, Scarbrough T, ApSimon Het al., 2012, Pollution abatement from road transport: cross-sectoral implications, climate co-benefits and behavioural change, ENVIRONMENTAL SCIENCE & POLICY, Vol: 19-20, Pages: 16-32, ISSN: 1462-9011

Journal article

Oxley T, ApSimon H, Valiantis M, 2011, Modelling national air quality strategy scenarios with UKIAM: uncertainties emerging from the integration of multiple spatial scales, INTERNATIONAL JOURNAL OF ENVIRONMENT AND POLLUTION, Vol: 44, Pages: 54-61, ISSN: 0957-4352

Journal article

Oxley T, Hall J, ApSimon H, 2011, Spatialities and temporalities of metrics calculated by Integrated Assessment Models: Exceedance of ecosystem-specific Critical Loads, MSSANZ 19th Biennial Congress on Modelling and Simulation (MODSIM), Publisher: MODELLING & SIMULATION SOC AUSTRALIA & NEW ZEALAND INC, Pages: 1795-1802

Conference paper

Oxley T, ApSimon H, 2011, A conceptual framework for mapping uncertainty in integrated assessment, MSSANZ 19th Biennial Congress on Modelling and Simulation (MODSIM), Publisher: MODELLING & SIMULATION SOC AUSTRALIA & NEW ZEALAND INC, Pages: 1803-1809

Conference paper

Apsimon H, Amann M, Astrom S, Oxley Tet al., 2009, Synergies in addressing air quality and climate change, CLIMATE POLICY, Vol: 9, Pages: 669-680, ISSN: 1469-3062

Journal article

Oxley T, Valiantis M, Elshkaki A, ApSimon HMet al., 2009, Background, Road and Urban Transport modelling of Air quality Limit values (The BRUTAL model), ENVIRONMENTAL MODELLING & SOFTWARE, Vol: 24, Pages: 1036-1050, ISSN: 1364-8152

Journal article

Reis S, Sabel C, Oxley T, 2009, Implications of different spatial (and temporal) resolutions for integrated assessment modelling on the regional to local scale - nesting, coupling, or model integration?, IMACS World Congress/Modelling and Simulation Society-of-Australia-and-New-Zealand (MSSANZ)/18th MODSIM09 Biennial Conference on Modelling and Simulation, Publisher: MODELLING & SIMULATION SOC AUSTRALIA & NEW ZEALAND INC, Pages: 2328-2334

Conference paper

Valiantis M, Oxley T, ApSimon HM, 2007, Assessing alternative transport scenarios in relation to UK air quality strategy, 6th International Conference on Urban Air Quality

Conference paper

Oxley T, 2007, Spatial dynamics, networks and modelling, ENVIRONMENT AND PLANNING B-PLANNING & DESIGN, Vol: 34, Pages: 379-380, ISSN: 0265-8135

Journal article

Oxley T, ApSimon HM, 2007, Space, time and nesting Integrated Assessment Models, Environmental Modelling & Software, Vol: 22, Pages: 1732-1749

Journal article

LemonM, JeffreyP, McIntoshBS, OXLEYTet al., 2004, Understanding perceptions of change: A pathways contribution to community consultation and environmental decision-making, Journal of Environmental Assessment Policy & Management, Vol: 6, Pages: 189-211

Journal article

OXLEY T, ApSimon H, Grossinho A, 2004, Issues of scale in nested Integrated Assessment Models, Manno, Switzerland, Publisher: iEMSs

Conference paper

Oxley T, McIntosh BS, Winder N, Mulligan M, Engelen Get al., 2004, Integrated modelling and decision-support tools: a Mediterranean example, Environmental Modelling & Software, Pages: 999-1010

A great deal of new knowledge and research material have been generated from research carried out under the auspices of theEuropean Union (EU). However, only a small amount has been made available as practical policy-support tools. In this paper,we describe how EU funded research models and understanding have been integrated into an interactive decision-support systemaddressing physical, economic and social aspects of land degradation in the Mediterranean. We summarise the 10 constituentmodels that simulate hydrology, human influences, crops, natural vegetation and climatic conditions. The models operate on verydifferent spatial and temporal scales and utilise different modelling techniques and implementation languages. Many scientific,modelling and technical issues were encountered during the transformation of ‘research’ models into ‘policy’ models. We highlightthe differences between each type of model and discuss some of the ontological and technical problems in re-using research modelsfor policy-support, including resolving differences in temporal scale and some of the software engineering aspects of modelintegration. The involvement of policy-makers, ‘stakeholders’ and other end-users is essential for the specification of relevantdecision-making issues and the development of useful interactive support tools. We discuss the problems of identifying both thedecision-makers and the issues they perceive as important, their receptivity to such tools, and their roles in the policy-making process.Finally, we note the lessons learned, the resources needed, and the types of end-users, scientists and mediators required toensure effective communication, technical development and exploitation of spatial modelling tools for integrated environmentaldecision-making.

Journal article

Oxley T, Lemon M, 2003, From social-enquiry to decision support tools: towards an integrative method in the mediterranean rural environment, International Conference on the Future of the Mediterranean Rural Environment, Publisher: ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD, Pages: 595-617, ISSN: 0140-1963

Conference paper

This data is extracted from the Web of Science and reproduced under a licence from Thomson Reuters. You may not copy or re-distribute this data in whole or in part without the written consent of the Science business of Thomson Reuters.

Request URL: http://wlsprd.imperial.ac.uk:80/respub/WEB-INF/jsp/search-html.jsp Request URI: /respub/WEB-INF/jsp/search-html.jsp Query String: respub-action=search.html&id=00357450&limit=30&person=true