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  • Journal article
    Dehbi HM, Blangiardo M, Gulliver J, Fecht D, de Hoogh K, Al-Kanaani Z, Tillin T, Hardy R, Chaturvedi N, Hansell ALet al., 2016,

    Air pollution and cardiovascular mortality with over 25 years follow-up: A combined analysis of two British cohorts

    , Environment International, Vol: 99, Pages: 275-281, ISSN: 1873-6750

    BACKGROUND: Adverse effects of air pollution on cardiovascular disease (CVD) mortality are well established. There are comparatively fewer studies in Europe, and in the UK particularly, than in North America. We examined associations in two British cohorts with >25years of follow-up. METHODS: Annual average NO2, SO2 and black smoke (BS) air pollution exposure estimates for 1991 were obtained from land use regression models using contemporaneous monitoring data. From the European Study of Cohorts and Air Pollution (ESCAPE), air pollution estimates in 2010-11 were obtained for NO2, NOx, PM10, PMcoarse and PM2.5. The exposure estimates were assigned to place of residence 1989 for participants in a national birth cohort born in 1946, the MRC National Study of Health and Development (NSHD), and an adult multi-ethnic London cohort, Southall and Brent Revisited (SABRE) recruited 1988-91. The combined median follow-up was 26years. Single-pollutant competing risk models were employed, adjusting for individual risk factors. RESULTS: Elevated non-significant hazard ratios for CVD mortality were seen with 1991 BS and SO2 and with ESCAPE PM10 and PM2.5 in fully adjusted linear models. Per 10μg/m(3) increase HRs were 1.11 [95% CI: 0.76-1.61] for BS, 1.05 [95% CI: 0.91-1.22] for SO2, 1.16 [95% CI: 0.70-1.92] for PM10 and 1.30 [95% CI: 0.39-4.34] for PM2.5, with largest effects seen in the fourth quartile of BS and PM2.5 compared to the first with HR 1.24 [95% CI: 0.91-1.61] and 1.21 [95% CI: 0.88-1.66] respectively. There were no consistent associations with other ESCAPE pollutants, or with 1991 NO2. Modelling using Cox regression led to similar results. CONCLUSION: Our results support a detrimental long-term effect for air pollutants on cardiovascular mortality.

  • Journal article
    Jedynska A, Hoek G, Wang M, Yang A, Eeftens M, Cyrys J, Keuken M, Ampe C, Beelen R, Cesaroni G, Forastiere F, Cirach M, de Hoogh K, De Nazelle A, Nystad W, Akhlaghi HM, Declercq C, Stempfelet M, Eriksen KT, Dimakopoulou K, Lanki T, Meliefste K, Nieuwenhuijsen M, Yli-Tuomi T, Raaschou-Nielsen O, Janssen NAH, Brunekreef B, Kooter IMet al., 2016,

    Spatial variations and development of land use regression models of oxidative potential in ten European study areas

    , ATMOSPHERIC ENVIRONMENT, Vol: 150, Pages: 24-32, ISSN: 1352-2310
  • Journal article
    Donaire-Gonzalez D, Valentin A, de Nazelle A, Ambros A, Carrasco-Turigas G, Seto E, Jerrett M, Nieuwenhuijsen MJet al., 2016,

    Benefits of Mobile Phone Technology for Personal Environmental Monitoring

    , JMIR mHealth and uHealth, Vol: 4, ISSN: 2291-5222

    Background: Tracking individuals in environmental epidemiological studies using novel mobile phone technologies can provide valuable information on geolocation and physical activity, which will improve our understanding of environmental exposures.Objective: The objective of this study was to assess the performance of one of the least expensive mobile phones on the market to track people's travel-activity pattern.Methods: Adults living and working in Barcelona (72/162 bicycle commuters) carried simultaneously a mobile phone and a Global Positioning System (GPS) tracker and filled in a travel-activity diary (TAD) for 1 week (N=162). The CalFit app for mobile phones was used to log participants’ geographical location and physical activity. The geographical location data were assigned to different microenvironments (home, work or school, in transit, others) with a newly developed spatiotemporal map-matching algorithm. The tracking performance of the mobile phones was compared with that of the GPS trackers using chi-square test and Kruskal-Wallis rank sum test. The minute agreement across all microenvironments between the TAD and the algorithm was compared using the Gwet agreement coefficient (AC1).Results: The mobile phone acquired locations for 905 (29.2%) more trips reported in travel diaries than the GPS tracker (P<.001) and had a median accuracy of 25 m. Subjects spent on average 57.9%, 19.9%, 9.0%, and 13.2% of time at home, work, in transit, and other places, respectively, according to the TAD and 57.5%, 18.8%, 11.6%, and 12.1%, respectively, according to the map-matching algorithm. The overall minute agreement between both methods was high (AC1 .811, 95% CI .810-.812).Conclusions: The use of mobile phones running the CalFit app provides better information on which microenvironments people spend their time in than previous approaches based only on GPS trackers. The improvements of mobile phone technology in microenvironment determination are because the m

  • Journal article
    Worth DJ, Stettler MEJ, Dickinson P, Hegarty K, Boies AMet al., 2016,

    Characterization and evaluation of methane oxidation catalysts for dual-fuel diesel and natural gas engines

    , Emission Control Science and Technology, Vol: 2, Pages: 204-214, ISSN: 2199-3629

    The UK has incentivized the use of natural gas in heavy goods vehicles (HGVs) by converting to dual-fuel (DF) diesel-natural gas systems to reduce noxious and greenhouse gas emissions. Laboratory and on-road measurements of DF vehicles have demonstrated a decrease in CO2 emissions relative to diesel, but there is an increase in greenhouse gas (CO2e) emissions because of unburned methane. Decreasing tailpipe emissions of methane via after-treatment devices in lean-burn compression ignition engines is a challenge because of low exhaust temperatures (∼400 °C) and the presence of water vapor. In this study, six commercially available methane oxidation catalysts (MOCs) were tested for their application in DF HGV vehicles. Each MOC was characterized in terms of the catalyst platinum group metal (PGM) loading (both Pd and Pt), particle size, catalytic surface area, and Pd:Pt ratio. In addition, the washcoat surface area, pore volume, and pore size were evaluated. The MOC conversion efficiency was evaluated in controlled methane-oxidation experiments with varying temperatures, flow rates, and gas compositions. Characteristic-conversion efficiency correlations demonstrate that the influential MOC characteristics were PGM loading (both Pd and Pt), Pd:Pt ratio, washcoat surface area, and washcoat pore volume. With 90 % methane oxidation at less than 400 °C in DF HGV exhaust conditions, sample 1 had the highest conversion efficiency because of a high PGM loading (330 g/ft3, 12,000 g/m3), a 5.9 Pd:Pt ratio, a high alumina washcoat surface area of 20 m2/cm3, and 74-mm3/cm3 pore volume. Additional studies showed increased MOC conversion efficiency with decreasing gas hourly space velocities (GHSVs) and increasing methane concentrations.

  • Journal article
    O'Driscoll R, ApSimon HM, Oxley T, Molden N, Stettler MEJ, Thiyagarajah Aet al., 2016,

    A Portable Emissions Measurement System (PEMS) study of NO<inf>x</inf> and primary NO<inf>2</inf> emissions from Euro 6 diesel passenger cars and comparison with COPERT emission factors

    , Atmospheric Environment, Vol: 145, Pages: 81-91, ISSN: 1352-2310

    © 2016 Elsevier Ltd 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 to 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
    Bishop JDK, Stettler MEJ, Molden N, Boies AMet al., 2016,

    Engine maps of fuel use and emissions from transient driving cycles

    , Applied Energy, Vol: 183, Pages: 202-217, ISSN: 0306-2619

    Air pollution problems persist in many cities throughout the world, despite drastic reductions in regulated emissions of criteria pollutants from vehicles when tested on standardised driving cycles. New vehicle emissions regulations in the European Union and United States require the use of OBD and portable emissions measurement systems (PEMS) to confirm vehicles meet specified limits during on-road operation. The resultant in-use testing will yield a large amount of OBD and PEMS data across a range of vehicles. If used properly, the availability of OBD and PEMS data could enable greater insight into the nature of real-world emissions and allow detailed modelling of vehicle energy use and emissions. This paper presents a methodology to use this data to create engine maps of fuel use and emissions of nitrous oxides (NOx), carbon dioxide (CO2) and carbon monoxide (CO). Effective gear ratios, gearbox shift envelopes, candidate engine maps and a set of vehicle configurations are simulated over driving cycles using the ADVISOR powertrain simulation tool. This method is demonstrated on three vehicles – one truck and two passenger cars – tested on a vehicle dynamometer and one driven with a PEMS. The optimum vehicle configuration and associated maps were able to reproduce the shape and magnitude of observed fuel use and emissions on a per second basis. In general, total simulated fuel use and emissions were within 5% of observed values across the three test cases. The fitness of this method for other purposes was demonstrated by creating cold start maps and isolating the performance of tailpipe emissions reduction technologies. The potential of this work extends beyond the creation of vehicle engine maps to allow investigations into: emissions hot spots; real-world emissions factors; and accurate air quality modelling using simulated per second emissions from vehicles operating in over any driving cycle.

  • Journal article
    Dickau M, Olfert J, Stettler MEJ, Boies A, Momenimovahed A, Thomson K, Smallwood G, Johnson Met al., 2016,

    Methodology for quantifying the volatile mixing state of an aerosol

    , Aerosol Science and Technology, Vol: 50, Pages: 759-772, ISSN: 0278-6826

    Mixing state refers to the relative proportions of chemical species in an aerosol, and the way these species are combined; either as a population where each particle consists of a single species (‘externally mixed’) or where all particles individually consist of two or more species (‘internally mixed’) or the case where some particles are pure and some particles consist of multiple species. The mixing state affects optical and hygroscopic properties, and quantifying it is therefore important for studying an aerosol's climate impact. In this article, we describe a method to quantify the volatile mixing state of an aerosol using a differential mobility analyzer, centrifugal particle mass analyzer, catalytic denuder, and condensation particle counter by measuring the mass distributions of the volatile and non-volatile components of an aerosol and determining how the material is mixed within and between particles as a function of mobility diameter. The method is demonstrated using two aerosol samples from a miniCAST soot generator, one with a high elemental carbon (EC) content, and one with a high organic carbon (OC) content. The measurements are presented in terms of the mass distribution of the volatile and non-volatile material, as well as measures of diversity and mixing state parameter. It was found that the high-EC soot nearly consisted of only pure particles where 86% of the total mass was non-volatile. The high-OC soot consisted of either pure volatile particles or particles that contained a mixture of volatile and non-volatile material where 8% of the total mass was pure volatile particles and 70% was non-volatile material (with the remaining 22% being volatile material condensed on non-volatile particles). © 2016 American Association for Aerosol Research

  • Journal article
    Gulliver J, de Hoogh K, Hoek G, Vienneau D, Fecht D, Hansell Aet al., 2016,

    Back-extrapolated and year-specific NO2 land use regression models for Great Britain - Do they yield different exposure assessment?

    , Environment International, Vol: 92-93, Pages: 202-209, ISSN: 1873-6750

    Robust methods to estimate historic population air pollution exposures are important tools for epidemiological studies evaluating long-term health effects. We developed land use regression (LUR) models for NO2 exposure in Great Britain for 1991 and explored whether the choice of year-specific or back-extrapolated LUR yields 1) similar LUR variables and model performance, and 2) similar national and regional address-level and small-area concentrations. We constructed two LUR models for 1991using NO2 concentrations from the diffusion tube monitoring network, one using 75% of all available measurement sites (that over-represent industrial areas), and the other using 75% of a subset of sites proportionate to population by region to study the effects of monitoring site selection bias. We compared, using the remaining (hold-out) 25% of monitoring sites, the performance of the two 1991 models with back-extrapolation of a previously published 2009 model, developed using NO2 concentrations from automatic chemiluminescence monitoring sites and predictor variables from 2006/2007. The 2009 model was back-extrapolated to 1991 using the same predictors (1990 & 1995) used to develop 1991 models. The 1991 models included industrial land use variables, not present for 2009. The hold-out performance of 1991 models (mean-squared-error-based-R2: 0.62–0.64) was up to 8% higher and ~ 1 μg/m3 lower in root mean squared error than the back-extrapolated 2009 model, with best performance from the subset of sites representing population exposures. Year-specific and back-extrapolated exposures for residential addresses (n = 1.338,399) and small areas (n = 10.518) were very highly linearly correlated for Great Britain (r > 0.83). This study suggests that year-specific model for 1991 and back-extrapolation of the 2009 LUR yield similar exposure assessment.

  • Journal article
    Stettler MEJ, Midgley WJB, Swanson JJ, Cebon D, Boies AMet al., 2016,

    Greenhouse gas and noxious emissions from dual fuel diesel and natural gas heavy goods vehicles

    , Environmental Science & Technology, Vol: 50, Pages: 2018-2026, ISSN: 0013-936X

    Dual fuel diesel and natural gas heavy goods vehicles (HGVs) operate on a combination of the two fuels simultaneously. By substituting diesel for natural gas, vehicle operators can benefit from reduced fuel costs and as natural gas has a lower CO2 intensity compared to diesel, dual fuel HGVs have the potential to reduce greenhouse gas (GHG) emissions from the freight sector. In this study, energy consumption, greenhouse gas and noxious emissions for five after-market dual fuel configurations of two vehicle platforms are compared relative to their diesel-only baseline values over transient and steady state testing. Over a transient cycle, CO2 emissions are reduced by up to 9%; however, methane (CH4) emissions due to incomplete combustion lead to CO2e emissions that are 50–127% higher than the equivalent diesel vehicle. Oxidation catalysts evaluated on the vehicles at steady state reduced CH4 emissions by at most 15% at exhaust gas temperatures representative of transient conditions. This study highlights that control of CH4 emissions and improved control of in-cylinder CH4 combustion are required to reduce total GHG emissions of dual fuel HGVs relative to diesel vehicles.

  • Journal article
    Fecht D, Hansell A, Morley D, Dajnak D, Vienneau D, Beevers S, Toledano M, Kelly F, Anderson HR, Gulliver Jet al., 2016,

    Spatial and temporal associations of road traffic noise and air pollution in London: Implications for epidemiological studies

    , Environment International, Vol: 88, Pages: 235-242, ISSN: 0160-4120
  • Journal article
    Halonen JI, Blangiardo M, Toledano MB, Fecht D, Gulliver J, Anderson HR, Beevers SD, Dajnak D, Kelly F, Tonne Cet al., 2016,

    Long-term exposure to traffic pollution and hospital admissions in London

    , Environmental pollution, Vol: 208, Pages: 48-57, ISSN: 1873-6424
  • Journal article
    Halonen JI, Blangiardo M, Toledano MB, Fecht D, Gulliver J, Ghosh R, Anderson HR, Beevers S, Dajnak D, Kelly F, Wilkinson P, Tonne Cet al., 2016,

    Is long-term exposure to traffic pollution associated with mortality? A small-area study in London

    , Environmental Pollution, Vol: 208, Pages: 25-32, ISSN: 0269-7491
  • Journal article
    Smyth E, Solomon A, Vydyanath A, Luther PK, Pitchford S, Tetley TD, Emerson Met al., 2014,

    Induction and enhancement of platelet aggregation in vitro and in vivo by model polystyrene nanoparticles

    , Nanotoxicology, Vol: 9, Pages: 356-364, ISSN: 1743-5404

    Abstract Nanoparticles (NPs) may come into contact with circulating blood elements including platelets following inhalation and translocation from the airways to the bloodstream or during proposed medical applications. Studies with model polystyrene latex nanoparticles (PLNPs) have shown that NPs are able to induce platelet aggregation in vitro suggesting a poorly defined potential mechanism of increased cardiovascular risk upon NP exposure. We aimed to provide insight into the mechanisms by which NPs may increase cardiovascular risk by determining the impact of a range of concentrations of PLNPs on platelet activation in vitro and in vivo and identifying the signaling events driving NP-induced aggregation. Model PLNPs of varying nano-size (50 and 100 nm) and surface chemistry [unmodified (uPLNP), amine-modified (aPLNP) and carboxyl-modified (cPLNP)] were therefore examined using in vitro platelet aggregometry and an established mouse model of platelet thromboembolism. Most PLNPs tested induced GPIIb/IIIa-mediated platelet aggregation with potencies that varied with both surface chemistry and nano-size. Aggregation was associated with signaling events, such as granule secretion and release of secondary agonists, indicative of conventional agonist-mediated aggregation. Platelet aggregation was associated with the physical interaction of PLNPs with the platelet membrane or internalization. 50 nm aPLNPs acted through a distinct mechanism involving the physical bridging of adjacent non-activated platelets leading to enhanced agonist-induced aggregation in vitro and in vivo. Our study suggests that should they translocate the pulmonary epithelium, or be introduced into the blood, NPs may increase the risk of platelet-driven events by inducing or enhancing platelet aggregation via mechanisms that are determined by their distinct combination of nano-size and surface chemistry.

  • Journal article
    Rojas-Rueda D, de Nazelle A, Teixido O, Nieuwenhuijsen MJet al., 2013,

    Health impact assessment of increasing public transport and cycling use in Barcelona: A morbidity and burden of disease approach

    , PREVENTIVE MEDICINE, Vol: 57, Pages: 573-579, ISSN: 0091-7435
  • Journal article
    Ragettli MS, Corradi E, Braun-Faehrlaender C, Schindler C, de Nazelle A, Jerrett M, Ducret-Stich RE, Kuenzli N, Phuleria HCet al., 2013,

    Commuter exposure to ultrafine particles in different urban locations, transportation modes and routes

    , ATMOSPHERIC ENVIRONMENT, Vol: 77, Pages: 376-384, ISSN: 1352-2310
  • Journal article
    de Nazelle A, Aguilera I, Nieuwenhuijsen M, Beelen R, Cirach M, Hoek G, de Hoogh K, Sunyer J, Targa J, Brunekreef B, Kuenzli N, Basagana Xet al., 2013,

    Comparison of performance of land use regression models derived for Catalunya, Spain

    , ATMOSPHERIC ENVIRONMENT, Vol: 77, Pages: 598-606, ISSN: 1352-2310
  • Journal article
    Solomon A, Smyth E, Mitha N, Pitchford S, Vydyanath A, Luther PK, Thorley AJ, Tetley TD, Emerson Met al., 2013,

    Induction of platelet aggregation after a direct physical interaction with diesel exhaust particles

    , JOURNAL OF THROMBOSIS AND HAEMOSTASIS, Vol: 11, Pages: 325-334, ISSN: 1538-7933

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