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  • Journal article
    Popoola OAM, Carruthers D, Lad C, Bright VB, Mead M, Stettler MEJ, Saffell JR, Jons RLet al., 2018,

    Use of networks of low cost air quality sensors to quantify air quality in urban settings

    , Atmospheric Environment, Vol: 194, Pages: 58-70, ISSN: 1352-2310

    Low cost sensors are becoming increasingly available for studying urban air quality. Here we show how such sensors, deployed as a network, provide unprecedented insights into the patterns of pollutant emissions, in this case at London Heathrow Airport (LHR). Measurements from the sensor network were used to unequivocally distinguish airport emissions from long range transport, and then to infer emission indices from the various airport activities. These were used to constrain an air quality model (ADMS-Airport), creating a powerful predictive tool for modelling pollutant concentrations. For nitrogen dioxide (NO2), the results show that the non-airport component is the dominant fraction (∼75%) of annual NO2 around the airport and that despite a predicted increase in airport related NO2 with an additional runway, improvements in road traffic fleet emissions are likely to more than offset this increase. This work focusses on London Heathrow Airport, but the sensor network approach we demonstrate has general applicability for a wide range of environmental monitoring studies and air pollution interventions.

  • Report
    Pimpin L, Retat L, Fecht D, de Preux Gallone LB, Sassi F, Gulliver J, Belloni A, Ferguson B, Corbould E, Jaccard A, Webber Let al., 2018,

    Estimation of costs to the NHS and social care due to the health impacts of air pollution

  • Journal article
    Williams ML, Lott MC, Kitwiroon N, Dajnak D, Walton H, Holland M, Pye S, Fecht D, Toledano MB, Beevers SDet al., 2018,

    The Lancet countdown on health benefits from the UK Climate Change Act: a modelling study for Great Britain

    , Lancet Planetary Health, Vol: 2, Pages: e202-e213, ISSN: 2542-5196

    BACKGROUND: Climate change poses a dangerous and immediate threat to the health of populations in the UK and worldwide. We aimed to model different scenarios to assess the health co-benefits that result from mitigation actions. METHODS: In this modelling study, we combined a detailed techno-economic energy systems model (UK TIMES), air pollutant emission inventories, a sophisticated air pollution model (Community Multi-scale Air Quality), and previously published associations between concentrations and health outcomes. We used four scenarios and focused on the air pollution implications from fine particulate matter (PM2·5), nitrogen dioxide (NO2) and ozone. The four scenarios were baseline, which assumed no further climate actions beyond those already achieved and did not meet the UK's Climate Change Act (at least an 80% reduction in carbon dioxide equivalent emissions by 2050 compared with 1990) target; nuclear power, which met the Climate Change Act target with a limited increase in nuclear power; low-greenhouse gas, which met the Climate Change Act target without any policy constraint on nuclear build; and a constant scenario that held 2011 air pollutant concentrations constant until 2050. We predicted the health and economic impacts from air pollution for the scenarios until 2050, and the inequalities in exposure across different socioeconomic groups. FINDINGS: NO2 concentrations declined leading to 4 892 000 life-years saved for the nuclear power scenario and 7 178 000 life-years saved for the low-greenhouse gas scenario from 2011 to 2154. However, the associations that we used might overestimate the effects of NO2 itself. PM2·5 concentrations in Great Britain are predicted to decrease between 42% and 44% by 2050 compared with 2011 in the scenarios that met the Climate Change Act targets, especially those from road traffic and off-road machinery. These reductions in PM2·5 are tempered by a 2035 peak (and subsequent decline) in biomass (wood

  • Journal article
    Tonne C, Milà C, Fecht D, Alvarez M, Gulliver J, Smith J, Beevers S, Ross Anderson H, Kelly Fet al., 2018,

    Socioeconomic and ethnic inequalities in exposure to air and noise pollution in London

    , Environment International, Vol: 115, Pages: 170-179, ISSN: 0160-4120

    BACKGROUND: Transport-related air and noise pollution, exposures linked to adverse health outcomes, varies within cities potentially resulting in exposure inequalities. Relatively little is known regarding inequalities in personal exposure to air pollution or transport-related noise. OBJECTIVES: Our objectives were to quantify socioeconomic and ethnic inequalities in London in 1) air pollution exposure at residence compared to personal exposure; and 2) transport-related noise at residence from different sources. METHODS: We used individual-level data from the London Travel Demand Survey (n = 45,079) between 2006 and 2010. We modeled residential (CMAQ-urban) and personal (London Hybrid Exposure Model) particulate matter <2.5 μm and nitrogen dioxide (NO2), road-traffic noise at residence (TRANEX) and identified those within 50 dB noise contours of railways and Heathrow airport. We analyzed relationships between household income, area-level income deprivation and ethnicity with air and noise pollution using quantile and logistic regression. RESULTS: We observed inverse patterns in inequalities in air pollution when estimated at residence versus personal exposure with respect to household income (categorical, 8 groups). Compared to the lowest income group (<£10,000), the highest group (>£75,000) had lower residential NO2 (-1.3 (95% CI -2.1, -0.6) μg/m3 in the 95th exposure quantile) but higher personal NO2 exposure (1.9 (95% CI 1.6, 2.3) μg/m3 in the 95th quantile), which was driven largely by transport mode and duration. Inequalities in residential exposure to NO2 with respect to area-level deprivation were larger at lower exposure quantiles (e.g. estimate for NO2 5.1 (95% CI 4.6, 5.5) at quantile 0.15 versus 1.9 (95% CI 1.1, 2.6) at quantile 0.95), reflecting low-deprivation, high residential NO2 areas in the city centre. Air pollution exposure at residence consistently overestimated personal exposure; this overestimation varied with age

  • Journal article
    Cai Y, Hansell A, Hodgson S, Elliott P, Fecht D, Gulliver J, Key T, de Hoogh K, Hveem K, Morley D, Vienneau D, Blangiardo Met al.,

    Road traffic noise, air pollution and incident cardiovascular disease: a joint analysis of the HUNT, EPIC-Oxford and UK Biobank cohorts

    , Environment International, ISSN: 0160-4120

    Background: This study aimed to investigate the effects of long-term exposure to road traffic noiseand air pollutionon incident cardiovascular disease (CVD)in three large cohorts: HUNT, EPIC-Oxford and UK Biobank. Methods: In pooled complete-casesample of the three cohorts from Norway and the United Kingdom(N=355,732), 21,081 incident all CVD cases including 5,259ischemic heart disease (IHD)and 2,871cerebrovascular cases were ascertained between baseline (1993-2010)and end of follow-up (2008-2013)through medical recordlinkage. Annual mean 24-hour weighted road traffic noise(Lden) and air pollution (particulate matter with aerodynamic diameter ≤10 μm [PM10],≤2.5 μm [PM2.5]andnitrogen 39dioxide[NO2])exposure at baseline address was modelled using a simplified version of the Common Noise Assessment Methods in Europe (CNOSSOS-EU)and European-wide Land Use Regression models.Individual-level covariate data were harmonised and physically pooled across the three cohorts. Analysis was via Cox proportional hazard model with mutual adjustmentsforboth noise and air pollution andpotential confounders. Results: No significant associations were found between annual mean Ldenand incidentCVD,IHD or cerebrovascular disease in the overall populationexcept that the association withincident IHD was significantamong current-smokers.In the fully adjusted models including adjustmentfor Lden, an interquartile range (IQR) higher PM10(4.1μg/m3) or PM2.5(1.4μg/m3) was associated witha5.8% (95%CI: 2.5%-9.3%) and 3.7% (95%CI: 0.2%-7.4%) higherrisk for all incident CVD respectively. No significant associations were found between NO2and any of the CVD outcomes. Conclusions: We found suggestive evidence of a possible association between road traffic noise and incident IHD, consistent with current literature. Long-term particulate air pollution exposure, even at concentrations below current European air quality standards, w

  • Journal article
    Gulliver J, Elliott P, Hansell A, Cai Y, McCrea A, Garwood K, Fecht D, Briggs Det al., 2018,

    Local- and regional-scale air pollution modelling (PM10) and exposure assessment for pregnancy trimesters, infancy, and childhood to age 15 years: Avon Longitudinal Study of Parents And Children (ALSPAC).

    , Environment International, Vol: 113, Pages: 10-19, ISSN: 0160-4120

    We established air pollution modelling to study particle (PM10) exposures during pregnancy and infancy (1990–1993) through childhood and adolescence up to age ~15 years (1991–2008) for the Avon Longitudinal Study of Parents And Children (ALSPAC) birth cohort. For pregnancy trimesters and infancy (birth to 6 months; 7 to 12 months) we used local (ADMS-Urban) and regional/long-range (NAME-III) air pollution models, with a model constant for local, non-anthropogenic sources. For longer exposure periods (annually and the average of birth to age ~8 and to age ~15 years to coincide with relevant follow-up clinics) we assessed spatial contrasts in local sources of PM10 with a yearly-varying concentration for all background sources. We modelled PM10 (μg/m3) for 36,986 address locations over 19 years and then accounted for changes in address in calculating exposures for different periods: trimesters/infancy (n = 11,929); each year of life to age ~15 (n = 10,383). Intra-subject exposure contrasts were largest between pregnancy trimesters (5th to 95th centile: 24.4–37.3 μg/m3) and mostly related to temporal variability in regional/long-range PM10. PM10 exposures fell on average by 11.6 μg/m3 from first year of life (mean concentration = 31.2 μg/m3) to age ~15 (mean = 19.6 μg/m3), and 5.4 μg/m3 between follow-up clinics (age ~8 to age ~15). Spatial contrasts in 8-year average PM10 exposures (5th to 95th centile) were relatively low: 25.4–30.0 μg/m3 to age ~8 years and 20.7–23.9 μg/m3 from age ~8 to age ~15 years. The contribution of local sources to total PM10 was 18.5%–19.5% during pregnancy and infancy, and 14.4%–17.0% for periods leading up to follow-up clinics. Main roads within the study area contributed on average ~3.0% to total PM10 exposures in all periods; 9.5% of address locations were within 50 m of a main road. Exposure estimates will be used in a number of planned epidemiological studies.

  • Journal article
    Smith RB, Fecht D, Gulliver J, Beevers SD, Dajnak D, Blangiardo M, Ghosh RE, Hansell AL, Kelly FJ, Anderson HR, Toledano MBet al., 2017,

    Impacts of London's road traffic air and noise pollution on birth weight: a retrospective population-based cohort study

    , BMJ, Vol: 359, ISSN: 0959-8138

    Objective To investigate the relation between exposure to both air and noise pollution from road traffic and birth weight outcomes.Design Retrospective population based cohort study.Setting Greater London and surrounding counties up to the M25 motorway (2317 km2), UK, from 2006 to 2010.Participants 540 365 singleton term live births.Main outcome measures Term low birth weight (LBW), small for gestational age (SGA) at term, and term birth weight.Results Average air pollutant exposures across pregnancy were 41 μg/m3 nitrogen dioxide (NO2), 73 μg/m3 nitrogen oxides (NOx), 14 μg/m3 particulate matter with aerodynamic diameter <2.5 μm (PM2.5), 23 μg/m3 particulate matter with aerodynamic diameter <10 μm (PM10), and 32 μg/m3 ozone (O3). Average daytime (LAeq,16hr) and night-time (Lnight) road traffic A-weighted noise levels were 58 dB and 53 dB respectively. Interquartile range increases in NO2, NOx, PM2.5, PM10, and source specific PM2.5 from traffic exhaust (PM2.5 traffic exhaust) and traffic non-exhaust (brake or tyre wear and resuspension) (PM2.5 traffic non-exhaust) were associated with 2% to 6% increased odds of term LBW, and 1% to 3% increased odds of term SGA. Air pollutant associations were robust to adjustment for road traffic noise. Trends of decreasing birth weight across increasing road traffic noise categories were observed, but were strongly attenuated when adjusted for primary traffic related air pollutants. Only PM2.5 traffic exhaust and PM2.5 were consistently associated with increased risk of term LBW after adjustment for each of the other air pollutants. It was estimated that 3% of term LBW cases in London are directly attributable to residential exposure to PM2.5>13.8 μg/m3during pregnancy.Conclusions The findings suggest that air pollution from road traffic in London is adversely affecting fetal growth. The results suggest little evidence for an independent exposure-response effect of traffic related noise on b

  • 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
    Koudis GS, Hu SJ, North RJ, Majumdar A, Stettler MEJet al., 2017,

    The impact of aircraft takeoff thrust setting on NO<inf>X</inf> emissions

    , Journal of Air Transport Management, Vol: 65, Pages: 191-197, ISSN: 0969-6997

    Reduced thrust takeoff has the potential to reduce aircraft-related NO X emissions at airports, however this remains to be investigated using flight data. This paper analyses the effect of takeoff roll thrust setting variability on the magnitude and spatial distribution of NO X emissions using high-resolution data records for 497 Airbus A319 activities at London Heathrow. Thrust setting varies between 67 and 97% of maximum, and aircraft operating in the bottom 10th percentile emit on average 514 g less NO X per takeoff roll (32% reduction) than the top 10th percentile, however this is dependent on takeoff roll duration. Spatial analysis suggests that peak NO X emissions, corresponding to the start of the takeoff roll, can be reduced by up to 25% by adopting reduced thrust takeoff activities. Furthermore, the length of the emission source also decreases. Consequently, the use of reduced thrust takeoff may enable improved local air quality at airports.

  • Journal article
    Jerrett M, Donaire-Gonzalez D, Popoola O, Jones R, Cohen RC, Almanza E, de Nazelle A, Mead I, Carrasco-Turigas G, Cole-Hunter T, Triguero-Mas M, Seto E, Nieuwenhuijsen Met al., 2017,

    Validating novel air pollution sensors to improve exposure estimates for epidemiological analyses and citizen science

    , Environmental Research, Vol: 158, Pages: 286-294, ISSN: 0013-9351

    Low cost, personal air pollution sensors may reduce exposure measurement errors in epidemiological investigations and contribute to citizen science initiatives. Here we assess the validity of a low cost personal air pollution sensor. Study participants were drawn from two ongoing epidemiological projects in Barcelona, Spain. Participants repeatedly wore the pollution sensor − which measured carbon monoxide (CO), nitric oxide (NO), and nitrogen dioxide (NO2). We also compared personal sensor measurements to those from more expensive instruments. Our personal sensors had moderate to high correlations with government monitors with averaging times of 1-h and 30-min epochs (r ~ 0.38–0.8) for NO and CO, but had low to moderate correlations with NO2 (~0.04–0.67). Correlations between the personal sensors and more expensive research instruments were higher than with the government monitors. The sensors were able to detect high and low air pollution levels in agreement with expectations (e.g., high levels on or near busy roadways and lower levels in background residential areas and parks). Our findings suggest that the low cost, personal sensors have potential to reduce exposure measurement error in epidemiological studies and provide valid data for citizen science studies.

  • Journal article
    Cai Y, Hodgson S, Blangiardo M, Gulliver J, Morley D, Vienneau D, de Hoogh K, Key T, Hveem K, Elliott P, Hansell Aet al., 2017,

    Road traffic noise and incident cardiovascular disease: a joint analysis of HUNT, EPIC-Oxford and UK Biobank

    , ICBEN 2017 Proceedings

    Aims: This study aimed to investigate the effects of long-term exposure to road traffic noise on incident CVD in three large cohorts: HUNT, EPIC-Oxford and UK Biobank. Methods: In a complete-case sample (N=361,699), 4,014 IHD and 2,109 cerebrovascular incident cases were ascertained between baseline (1993-2010) and end of follow-up (2008-2015) through medical record linkage. Annual mean road traffic noise exposure was modelled at baseline address. Individual-level covariate data were harmonised and data were pooled. Analyses used Cox proportional hazards model with adjustments for confounders, including air pollution. Results: For an interquartile range (IQR) (3.9 dBA) higher daytime noise, a non-significant association with incident IHD was seen (Hazard ratio (HR): 1.015, 95% Confidence Interval (CI): 0.989-1.042), fully adjusted. Statistically significant associations and interaction terms were seen in obese individuals (HR: 1.099, 95%CI: 1.029-1.174), and current-smokers (HR: 1.054, 95%CI: 1.007-1.103). No associations were found for ischemic or hemorrhagic stroke. Conclusions: Our study strengthens the evidence base for an effect of road traffic noise on incident IHD, whilst the association with incident stroke remains unclear.

  • Journal article
    Douglas P, Freni Sterrantino A, Leal Sanchez M, Ashworth D, Ghosh R, Fecht D, Font A, Blangiardo M, Gulliver J, Toledano MB, Elliott P, de Hoogh C, Fuller GW, Hansell Aet al., 2017,

    Estimating particulate exposure from modern Municipal Waste Incinerators (MWIs) in Great Britain.

    , Environmental Science & Technology, Vol: 51, Pages: 7511-7519, ISSN: 0013-936X

    Municipal Waste Incineration (MWI) is regulated through the European Union Directive on Industrial Emissions (IED), but there is ongoing public concern regarding potential hazards to health. Using dispersion modeling, we estimated spatial variability in PM10 concentrations arising from MWIs at postcodes (average 12 households) within 10 km of MWIs in Great Britain (GB) in 2003–2010. We also investigated change points in PM10 emissions in relation to introduction of EU Waste Incineration Directive (EU-WID) (subsequently transposed into IED) and correlations of PM10 with SO2, NOx, heavy metals, polychlorinated dibenzo-p-dioxins/furan (PCDD/F), polycyclic aromatic hydrocarbon (PAH) and polychlorinated biphenyl (PCB) emissions. Yearly average modeled PM10 concentrations were 1.00 × 10–5 to 5.53 × 10–2 μg m–3, a small contribution to ambient background levels which were typically 6.59–2.68 × 101 μg m–3, 3–5 orders of magnitude higher. While low, concentration surfaces are likely to represent a spatial proxy of other relevant pollutants. There were statistically significant correlations between PM10 and heavy metal compounds (other heavy metals (r = 0.43, p = <0.001)), PAHs (r = 0.20, p = 0.050), and PCBs (r = 0.19, p = 0.022). No clear change points were detected following EU-WID implementation, possibly as incinerators were operating to EU-WID standards before the implementation date. Results will be used in an epidemiological analysis examining potential associations between MWIs and health outcomes.

  • Journal article
    Smyth E, Solomon A, Birrell MA, Smallwood MJ, Winyard PG, Tetley TD, Emerson Met al., 2017,

    Influence of inflammation and nitric oxide upon platelet aggregation following deposition of diesel exhaust particles in the airways.

    , British Journal of Pharmacology, Vol: 174, Pages: 2130-2139, ISSN: 0007-1188

    Background and Purpose: Exposure to nanoparticulate pollution has been implicated in platelet-driven thrombotic events such as myocardial infarction. Inflammation and impairment of NO bioavailability have been proposed as potential causative mechanisms. It is unclear, however, whether airways exposure to combustion-derived nanoparticles such as diesel exhaust particles (DEP) or carbon black (CB) can augment platelet aggregation in vivo and the underlying mechanisms remain undefined. We aimed to investigate the effects of acute lung exposure to DEP and CB on platelet activation and the associated role of inflammation and endothelial-derived NO.Experimental Approach: DEP and CB were intratracheally instilled into wild-type (WT) and eNOS−/− mice and platelet aggregation was assessed in vivo using an established model of radio-labelled platelet thromboembolism. The underlying mechanisms were investigated by measuring inflammatory markers, NO metabolites and light transmission aggregometry.Key Results: Platelet aggregation in vivo was significantly enhanced in WT and eNOS−/− mice following acute airways exposure to DEP but not CB. CB exposure, but not DEP, was associated with significant increases in pulmonary neutrophils and IL-6 levels in the bronchoalveolar lavage fluid and plasma of WT mice. Neither DEP nor CB affected plasma nitrate/nitrite concentration and DEP-induced human platelet aggregation was inhibited by an NO donor.Conclusions and Implications: Pulmonary exposure to DEP and subsequent platelet activation may contribute to the reports of increased cardiovascular risk, associated with exposure to airborne pollution, independent of its effects on inflammation or NO bioavailability.

  • Journal article
    Koudis GS, Hu J, Majumdar A, Jones R, Stettler MEJet al., 2017,

    Airport emissions reductions from reduced thrust takeoff operations

    , Transportation Research Part D: Transport and Environment, Vol: 52, Pages: 15-28, ISSN: 1879-2340

    Given forecast aviation growth, many airports are predicted to reach capacity and require expansion. However, pressure to meet air quality regulations emphasises the importance of efficient ground-level aircraft activities to facilitate growth. Operational strategies such as reducing engine thrust setting at takeoff can reduce fuel consumption and pollutant emissions; however, quantification of the benefits and consistency of its use have been limited by data restrictions. Using 3,336 high-resolution flight data records, this paper analyses the impact of reduced thrust takeoff at London Heathrow. Results indicate that using reduced thrust takeoff reduces fuel consumption, nitrogen oxides (NOX) and black carbon (BC) emissions by 1.0-23.2%, 10.7-47.7%, and 49.0-71.7% respectively, depending on aircraft-engine combinations relative to 100% thrust takeoff. Variability in thrust settings for the same aircraft-engine combination and dependence on takeoff weight (TOW) is quantified. Consequently, aircraft-engine specific optimum takeoff thrust settings that minimise fuel consumption and pollutant emissions for different aircraft TOWs are presented. Further reductions of 1.9%, 5.8% and 6.5% for fuel consumption, NOX and BC emissions could be achieved, equating to reductions of approximately 0.4%, 3.5% and 3.3% in total ground level fuel consumption, NOX and BC emissions. These results quantify the contribution that reduced thrust operations offer towards achieving industry environmental targets and air quality compliance, and imply that the current implementation of reduced thrust takeoff at Heathrow is near optimal, considering operational and safety constraints.

  • Journal article
    Olfert JS, Dickau M, Momenimovahed A, Saffaripour M, Thompson K, Smallwood G, Stettler MEJ, Boies AM, Sevcenco Y, Crayford A, Johnson Met al., 2017,

    Effective density and volatility of particles sampled from a helicopter gas turbine engine

    , Aerosol Science and Technology, Vol: 51, Pages: 704-714, ISSN: 0278-6826

    The effective density and size-resolved volatility of particles emitted from a Rolls-Royce Gnome helicopter turboshaft engine are measured at two engine speed settings (13,000 and 22,000 RPM). The effective density of denuded and undenuded particles were measured. The denuded effective densities are similar to the effective densities of particles from a gas turbine with a double annular combustor as well as a wide variety of internal combustion engines. The denuded effective density measurements were also used to estimate the size and number of primary particles in the soot aggregates. The primary particle size estimates show that the primary particle size was smaller at lower engine speed (in agreement with transmission electron microscopy analysis). As a demonstration, the size-resolved volatility of particles emitted from the engine are measured with a system consisting of a differential mobility analyzer, centrifugal particle mass analyzer, condensation particle counter, and catalytic stripper. This system determines the number distributions of particles that contain or do not contain non-volatile material, and the mass distributions of non-volatile material, volatile material condensed onto the surface of non-volatile particles, and volatile material forming independent particles (e.g. nucleated volatile material). It was found that the particulate at 13,000 RPM contained a measurable fraction of purely volatile material with diameters below ∼25 nm and had a higher mass fraction of volatile material condensed on the surface of the soot (6–12%) compared to the 22,000 RPM condition (1–5%). This study demonstrates the potential to quantify the distribution of volatile particulate matter and gives additional information to characterize sampling effects with regulatory measurement procedures.

  • Journal article
    Dons E, Laeremans M, Orjuela JP, Avila-Palencia I, Carrasco-Turigas G, Cole-Hunter T, Anaya-Boig E, Standaert A, De Boever P, Nawrot T, Gotschi T, de Nazelle A, Nieuwenhuijsen M, Panis LIet al., 2017,

    Wearable sensors for personal monitoring and estimation of inhaled traffic-related air pollution: evaluation of methods

    , Environmental Science and Technology, Vol: 51, Pages: 1859-1867, ISSN: 0013-936X

    Physical activity and ventilation rates have an effect on an individual’s dose and may be important to consider in exposure–response relationships; however, these factors are often ignored in environmental epidemiology studies. The aim of this study was to evaluate methods of estimating the inhaled dose of air pollution and understand variability in the absence of a true gold standard metric. Five types of methods were identified: (1) methods using (physical) activity types, (2) methods based on energy expenditure, METs (metabolic equivalents of task), and oxygen consumption, (3) methods based on heart rate or (4) breathing rate, and (5) methods that combine heart and breathing rate. Methods were compared using a real-life data set of 122 adults who wore devices to track movement, black carbon air pollution, and physiological health markers for 3 weeks in three European cities. Different methods for estimating minute ventilation performed well in relative terms with high correlations among different methods, but in absolute terms, ignoring increased ventilation during day-to-day activities could lead to an underestimation of the daily dose by a factor of 0.08–1.78. There is no single best method, and a multitude of methods are currently being used to approximate the dose. The choice of a suitable method for determining the dose in future studies will depend on both the size and the objectives of the study.

  • Journal article
    de Nazelle A, Bode O, Orjuela JP, 2016,

    Comparison of air pollution exposures in active vs. passive travel modes in European cities: A quantitative review

    , Environment International, Vol: 99, Pages: 151-160, ISSN: 0160-4120

    Background:Transport microenvironments tend to have higher air pollutant concentrations than other settings most people encounter in their daily lives. The choice of travel modes may affect significantly individuals' exposures; however such considerations are typically not accounted for in exposure assessment used in environmental health studies. In particular, with increasing interest in the promotion of active travel, health impact studies that attempt to estimate potential adverse consequences of potential increased pollutant inhalation during walking or cycling have emerged. Such studies require a quantification of relative exposures in travel modes.Methods:The literature on air pollution exposures in travel microenvironments in Europe was reviewed. Studies which measured various travel modes including at least walking or cycling in a simultaneous or quasi-simultaneous design were selected. Data from these studies were harmonized to allow for a quantitative synthesis of the estimates. Ranges of ratios and 95% confidence interval (CI) of air pollution exposure between modes and between background and transportation modes were estimated.Results:Ten studies measuring fine particulate matter (PM2.5), black carbon (BC), ultrafine particles (UFP), and/or carbon monoxide (CO) in the walk, bicycle, car and/or bus modes were included in the analysis. Only three reported on CO and BC and results should be interpreted with caution. Pedestrians were shown to be the most consistently least exposed of all across studies, with the bus, bicycle and car modes on average 1.3 to 1.5 times higher for PM2.5; 1.1 to 1.7 times higher for UFP; and 1.3 to 2.9 times higher for CO; however the 95% CI included 1 for the UFP walk to bus ratio. Only for BC were pedestrians more exposed than bus users on average (bus to walk ratio 0.8), but remained less exposed than those on bicycles or in cars. Car users tended to be the most exposed (from 2.9 times higher than pedestrians for BC down to si

  • 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
    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 (NO x ) 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 NO x and primary NO 2 . 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 NO x traps (LNT), or selective catalytic reduction (SCR). The results show wide variability in NO x emissions from 1 to 22 times the type approval limit. The average NO x emission, 0.36 (sd. 0.36) g km −1 , is 4.5 times the Euro 6 limit. The average fraction primary NO 2 (fNO 2 ) 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 NO x and 2.5 times for NO 2 . However, by removing the 5 most polluting vehicles average emissions were reduced considerably.

  • Journal article
    Halonen JI, Blangiardo M, Toledano MB, Fecht D, Gulliver J, Anderson HR, Beevers SD, Dajnak D, Kelly FJ, 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

    Evidence on the effects of long-term exposure to traffic pollution on health is inconsistent. In Greater London we examined associations between traffic pollution and emergency hospital admissions for cardio-respiratory diseases by applying linear and piecewise linear Poisson regression models in a small-area analysis. For both models the results for children and adults were close to unity. In the elderly, linear models found negative associations whereas piecewise models found non-linear associations characterized by positive risks in the lowest and negative risks in the highest exposure category. An increased risk was observed among those living in areas with the highest socioeconomic deprivation. Estimates were not affected by adjustment for traffic noise. The lack of convincing positive linear associations between primary traffic pollution and hospital admissions agrees with a number of other reports, but may reflect residual confounding. The relatively greater vulnerability of the most deprived populations has important implications for public health.

  • 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 FJ, 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: 1873-6750

    Road traffic gives rise to noise and air pollution exposures, both of which are associated with adverse health effects especially for cardiovascular disease, but mechanisms may differ. Understanding the variability in correlations between these pollutants is essential to understand better their separate and joint effects on human health.We explored associations between modelled noise and air pollutants using different spatial units and area characteristics in London in 2003–2010.We modelled annual average exposures to road traffic noise (LAeq,24 h, Lden, LAeq,16 h, Lnight) for ~ 190,000 postcode centroids in London using the UK Calculation of Road Traffic Noise (CRTN) method. We used a dispersion model (KCLurban) to model nitrogen dioxide, nitrogen oxide, ozone, total and the traffic-only component of particulate matter ≤ 2.5 μm and ≤ 10 μm. We analysed noise and air pollution correlations at the postcode level (~ 50 people), postcodes stratified by London Boroughs (~ 240,000 people), neighbourhoods (Lower layer Super Output Areas) (~ 1600 people), 1 km grid squares, air pollution tertiles, 50 m, 100 m and 200 m in distance from major roads and by deprivation tertiles.Across all London postcodes, we observed overall moderate correlations between modelled noise and air pollution that were stable over time (Spearman's rho range: | 0.34–0.55 |). Correlations, however, varied considerably depending on the spatial unit: largest ranges were seen in neighbourhoods and 1 km grid squares (both Spearman's rho range: | 0.01–0.87 |) and was less for Boroughs (Spearman's rho range: | 0.21–0.78 |). There was little difference in correlations between exposure tertiles, distance from road or deprivation tertiles.Associations between noise and air pollution at the relevant geographical unit of analysis need to be carefully considered in any epidemiological analysis, in particular in complex urban areas. Low correlations near roads, however, sugges

  • Journal article
    Halonen JI, Blangiardo M, Toledano MB, Fecht D, Gulliver J, Ghosh R, Anderson HR, Beevers SD, Dajnak D, Kelly FJ, Wilkinson P, Tonne Cet al., 2015,

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

    , Environmental Pollution, ISSN: 1873-6424

    Long-term exposure to primary traffic pollutants may be harmful for health but few studies have investigated effects on mortality. We examined associations for six primary traffic pollutants with all-cause and cause-specific mortality in 2003-2010 at small-area level using linear and piecewise linear Poisson regression models. In linear models most pollutants showed negative or null association with all-cause, cardiovascular or respiratory mortality. In the piecewise models we observed positive associations in the lowest exposure range (e.g. relative risk (RR) for all-cause mortality 1.07 (95% credible interval (CI) = 1.00-1.15) per 0.15 μg/m(3) increase in exhaust related primary particulate matter ≤2.5 μm (PM2.5)) whereas associations in the highest exposure range were negative (corresponding RR 0.93, 95% CI: 0.91-0.96). Overall, there was only weak evidence of positive associations with mortality. That we found the strongest positive associations in the lowest exposure group may reflect residual confounding by unmeasured confounders that varies by exposure group.

  • 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
    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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