Imperial College London

DrDavidGreen

Faculty of MedicineSchool of Public Health

Senior Research Fellow
 
 
 
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d.green

 
 
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Norfolk PlaceSt Mary's Campus

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Summary

 

Publications

Publication Type
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63 results found

Bressi M, Cavalli F, Putaud JP, Fröhlich R, Petit J-E, Aas W, Äijälä M, Alastuey A, Allan JD, Aurela M, Berico M, Bougiatioti A, Bukowiecki N, Canonaco F, Crenn V, Dusanter S, Ehn M, Elsasser M, Flentje H, Graf P, Green DC, Heikkinen L, Hermann H, Holzinger R, Hueglin C, Keernik H, Kiendler-Scharr A, Kubelová L, Lunder C, Maasikmets M, Makeš O, Malaguti A, Mihalopoulos N, Nicolas JB, O'Dowd C, Ovadnevaite J, Petralia E, Poulain L, Priestman M, Riffault V, Ripoll A, Schlag P, Schwarz J, Sciare J, Slowik J, Sosedova Y, Stavroulas I, Teinemaa E, Via M, Vodička P, Williams PI, Wiedensohler A, Young DE, Zhang S, Favez O, Minguillón MC, Prevot ASHet al., 2021, A European aerosol phenomenology - 7: High-time resolution chemical characteristics of submicron particulate matter across Europe, Atmospheric Environment: X, Vol: 10, Pages: 1-16, ISSN: 2590-1621

Similarities and differences in the submicron atmospheric aerosol chemical composition are analyzed from a unique set of measurements performed at 21 sites across Europe for at least one year. These sites are located between 35 and 62°N and 10° W – 26°E, and represent various types of settings (remote, coastal, rural, industrial, urban). Measurements were all carried out on-line with a 30-min time resolution using mass spectroscopy based instruments known as Aerosol Chemical Speciation Monitors (ACSM) and Aerosol Mass Spectrometers (AMS) and following common measurement guidelines. Data regarding organics, sulfate, nitrate and ammonium concentrations, as well as the sum of them called non-refractory submicron aerosol mass concentration ([NR-PM1]) are discussed. NR-PM1 concentrations generally increase from remote to urban sites. They are mostly larger in the mid-latitude band than in southern and northern Europe. On average, organics account for the major part (36–64%) of NR-PM1 followed by sulfate (12–44%) and nitrate (6–35%). The annual mean chemical composition of NR-PM1 at rural (or regional background) sites and urban background sites are very similar. Considering rural and regional background sites only, nitrate contribution is higher and sulfate contribution is lower in mid-latitude Europe compared to northern and southern Europe. Large seasonal variations in concentrations (μg/m³) of one or more components of NR-PM1 can be observed at all sites, as well as in the chemical composition of NR-PM1 (%) at most sites. Significant diel cycles in the contribution to [NR-PM1] of organics, sulfate, and nitrate can be observed at a majority of sites both in winter and summer. Early morning minima in organics in concomitance with maxima in nitrate are common features at regional and urban background sites. Daily variations are much smaller at a number of coastal and rural sites. Looking at NR-PM1 chemical composition as a func

Journal article

Hicks W, Beevers S, Tremper A, Stewart G, Priestman M, Kelly F, Lanoisellé M, Lowry D, Green Det al., 2021, Quantification of non-exhaust particulate matter traffic emissions and the impact of COVID-19 lockdown at London Marylebone Road, Atmosphere, Vol: 12, Pages: 1-19, ISSN: 2073-4433

This research quantifies current sources of non-exhaust particulate matter traffic emissions in London using simultaneous, highly time-resolved, atmospheric particulate matter mass and chemical composition measurements. The measurement campaign ran at Marylebone Road (roadside) and Honor Oak Park (background) urban monitoring sites over a 12-month period between 1 September 2019 and 31 August 2020. The measurement data has been used to determine the traffic increment (roadside – background) and covers a range of meteorological conditions, seasons and driving styles, as well as the influence of the COVID-19 ‘lockdown’ on non-exhaust concentrations. Non-exhaust PM10 concentrations are calculated using chemical tracer scaling factors for brake wear (barium), tyre wear (zinc) and resuspension (silicon) and as average vehicle fleet non-exhaust emission factors, using a CO2 ‘dilution approach’. The effect of lockdown, which saw a 32% reduction in traffic volume and a 15% increase in average speed on Marylebone Road, resulted in lower PM10 and PM2.5 traffic increments and brake wear concentrations, but similar tyre and resuspension concentrations, confirming that factors that determine non-exhaust emissions are complex. Brake wear was found to be the highest average non-exhaust emission source. In addition, results indicated that non-exhaust emission factors are dependent upon speed and road surface wetness conditions. Further statistical analysis incorporating a wider variability in vehicle mix, speeds and meteorological conditions, as well as advanced source apportionment of the PM measurement data, will be undertaken to enhance our understanding of these important vehicle sources.

Journal article

Analitis A, Barratt B, Green D, Beddows A, Samoli E, Schwartz J, Katsouyanni Ket al., 2020, Prediction of PM2.5 concentrations at the locations of monitoring sites measuring PM10 and NOx, using generalized additive models and machine learning methods: A case study in London, ATMOSPHERIC ENVIRONMENT, Vol: 240, ISSN: 1352-2310

Journal article

Font A, Tremper AH, Lin C, Priestman M, Marsh D, Woods M, Heal MR, Green DCet al., 2020, Air quality in enclosed railway stations: Quantifying the impact of diesel trains through deployment of multi-site measurement and random forest modelling., Environ Pollut, Vol: 262

Concentrations of the air pollutants (NO2 and particulate matter) were measured for several months and at multiple locations inside and outside two enclosed railway stations in the United Kingdom - Edinburgh Waverly (EDB) and London King's Cross (KGX) - which, respectively, had at the time 59% and 18% of their train services powered by diesel engines. Average concentrations of NO2 were above the 40 μg m-3 annual limit value outside the stations and were further elevated inside, especially at EDB. Concentrations of PM2.5 inside the stations were 30-40% higher at EDB than outside and up to 20% higher at KGX. Concentrations of both NO2 and PM2.5 were highest closer to the platforms, especially those with a higher frequency of diesel services. A random-forest regression model was used to quantify the impact of numbers of different types of diesel trains on measured concentrations allowing prediction of the impact of individual diesel-powered rolling stock.

Journal article

Desouza CD, Marsh DJ, Beevers SD, Molden N, Green DCet al., 2020, Real-world emissions from non-road mobile machinery in London, Atmospheric Environment, Vol: 223, ISSN: 1352-2310

The 2016 London atmospheric emissions inventory estimates that, the construction sector contributes 34% of the total PM and 7% of the total NO – the largest and 5 largest sources, respectively. Recent on-road light duty diesel vehicle emission tests have shown significant differences between real-world NO emissions compared with results from laboratory based regulatory tests. The aim of this study was therefore to quantify the ‘real-world’ tail-pipe NO , CO , and particle emissions, for 30 of the most commonly used construction machines in London under normal working conditions. The highest NO emissions (g/kWh) were from the older engines (Stage III-A ~4.88 g/kWh and III-B ~4.61 g/kWh), these were reduced significantly (~78%) in the newer (Stage IV ~1.05 g/kWh) engines due to more advanced engine management systems and exhaust after treatment. One Stage IV machine emitted NO similar to a Stage III-B machine, the failure of this SCR was only detectable using PEMS as no warning was given by the machine. Higher NO conformity factors were observed for Stage IV machines, due to the lower NO emission standards, which these machines must adhere to. On average, Stage III-B machines (~525 g/kWh) emitted the lowest levels of CO emissions, compared to Stage III-A (~875 g/kWh) and Stage IV (~575 g/kWh) machines. Overall, a statistically significant (~41%) decrease was observed in the CO emissions (g/kWh) between Stage III-A and III-B machines, while no statistically significant difference was found between Stage III-B and IV machines. Particle mass measurements, which were only measured from generators, showed that generators of all engine sizes were within their respective Stage III-A emission standards. A 95% reduction in NO and 2 orders of magnitude reduction in particle number was observed for a SCR-DPF retrofitted generator, compared to the same generator prior to exhaust gas after-treatment strategy. 10 X X X 2 X X X X 2 2 X th

Journal article

Zhang T, Wooster M, Green DC, Main Bet al., 2020, A mathematical approach to merging data from different trace gas/particulate sensors having dissimilar (T90) response times: Application to fire emission factor determination, Aerosol and Air Quality Research, Vol: 20, Pages: 281-290, ISSN: 1680-8584

Low cost atmospheric composition sensors are increasingly used in both air quality research and in air pollution monitoring. Those focused on particulates have generally rather rapid (T90) response times due to their reliance on light scattering methods. However, those electrochemical and NDIR sensors targeting trace gases such as, respectively, CO and CO typically respond very much slower, with T90 response times that can be further lengthened by the rate at which sample exchange occurs in the measurement cell. Data from these types of low cost sensors are often used to derive emission ratios [ERs] of two simultaneously measured atmospheric species, yet ER derivations made using data from sensors having dissimilar T90 values can be problematic, because any rapid change in the pollutant concentration can mean one sensor responding faster to the changing conditions than the other. Such situations are typical within biomass burning plumes, yet where such ER assessments are routinely required to generate the emissions factors (EFs) needed for biomass burning emissions calculations. Here we confirm that the ERs coming from such analyses can be strongly biased if differential sensor T90 effects remain unadjusted for, and we demonstrate a simple mathematical approach for undertaking this adjustment. The method is able to take data from a sensor taken with a particular T90 value and simulate that which would be collected from a sensor targeting the same species but with a different T90 value, and if the output T90 is selected to match that of the companion sensor measuring the second species then the two measures with the same effective T90 values can be used to generate unbiased emissions ratios and emissions factors. We demonstrate our approach on simulated data with known T90 response times, and then apply it to real data from low-cost sensors collected within biomass burning plumes, including those installed in a sampling system that introduced further – and unk

Journal article

Barratt BM, Fuller GW, Kelly FJ, Priestman M, Tremper AH, Green DCet al., 2020, PM2.5 on the London Underground, Environment International, Vol: 134, ISSN: 0160-4120

Introduction: Despite the London Underground (LU) handling on average 2.8 million passenger journeys per day, the characteristics and potential health effects of the elevated concentrations of metal-rich PM2.5 found in this subway system are not well understood. Methods: Spatial monitoring campaigns were carried out to characterise the health-relevant chemical and physical properties of PM2.5 across the LU network, including diurnal and day-to-day variability and spatial distribution (above ground, depth below ground and subway line). Population-weighted station PM2.5 rankings were produced to understand the relative importance of concentrations at different stations and on different lines. Results: The PM2.5 mass in the LU (mean 88 μg m−3, median 28 μg m−3) was greater than at ambient background locations (mean 19 μg m−3, median 14 μg m−3) and roadside environments in central London (mean 22 μg m−3, median 14 μg m−3). Concentrations varied between lines and locations, with the deepest and shallowest submerged lines being the District (median 4 μg m−3) and Victoria (median 361 μg m−3 but up to 885 μg m−3). Broadly in agreement with other subway systems around the world, sampled LU PM2.5 comprised 47% iron oxide, 7% elemental carbon, 11% organic carbon, and 14% metallic and mineral oxides. Although a relationship between line depth and air quality inside the tube trains was evident, there were clear influences relating to the distance from cleaner outside air and the exchange with cabin air when the doors open. The passenger population-weighted exposure analysis demonstrated a method to identify stations that should be prioritised for remediation to improve air quality. Conclusion: PM2.5 concentrations in the LU are many times higher than in other London transport Environments. Failure to include this environment in epidemiological studies of the relationship between PM2.5 and health in

Journal article

Rivas I, Beddows DCS, Amato F, Green DC, Järvi L, Hueglin C, Reche C, Timonen H, Fuller GW, Niemi JV, Pérez N, Aurela M, Hopke PK, Alastuey A, Kulmala M, Harrison RM, Querol X, Kelly FJet al., 2020, Source apportionment of particle number size distribution in urban background and traffic stations in four European cities, Environment International, Vol: 135, ISSN: 0160-4120

Ultrafine particles (UFP) are suspected of having significant impacts on health. However, there have only been a limited number of studies on sources of UFP compared to larger particles. In this work, we identified and quantified the sources and processes contributing to particle number size distributions (PNSD) using Positive Matrix Factorization (PMF) at six monitoring stations (four urban background and two street canyon) from four European cities: Barcelona, Helsinki, London, and Zurich. These cities are characterised by different meteorological conditions and emissions. The common sources across all stations were Photonucleation, traffic emissions (3 sources, from fresh to aged emissions: Traffic nucleation, Fresh traffic - mode diameter between 13 and 37 nm, and Urban - mode diameter between 44 and 81 nm, mainly traffic but influenced by other sources in some cities), and Secondary particles. The Photonucleation factor was only directly identified by PMF for Barcelona, while an additional split of the Nucleation factor (into Photonucleation and Traffic nucleation) by using NOx concentrations as a proxy for traffic emissions was performed for all other stations. The sum of all traffic sources resulted in a maximum relative contributions ranging from 71 to 94% (annual average) thereby being the main contributor at all stations. In London and Zurich, the relative contribution of the sources did not vary significantly between seasons. In contrast, the high levels of solar radiation in Barcelona led to an important contribution of Photonucleation particles (ranging from 14% during the winter period to 35% during summer). Biogenic emissions were a source identified only in Helsinki (both in the urban background and street canyon stations), that contributed importantly during summer (23% in urban background). Airport emissions contributed to Nucleation particles at urban background sites, as the highest concentrations of this source took place when the wind

Journal article

Saunders BM, Smith JD, Smith TEL, Green DC, Barratt Bet al., 2019, Spatial variability of fine particulate matter pollution (PM2.5) on the London Underground network, URBAN CLIMATE, Vol: 30, ISSN: 2212-0955

Journal article

Freney E, Zhang Y, Croteau P, Amodeo T, Williams L, Truong F, Petit J-E, Sciare J, Sarda-Esteve R, Bonnaire N, Arumae T, Aurela M, Bougiatioti A, Mihalopoulos N, Coz E, Artinano B, Crenn V, Elste T, Heikkinen L, Poulain L, Wiedensohler A, Herrmann H, Priestman M, Alastuey A, Stavroulas I, Tobler A, Vasilescu J, Zanca N, Canagaratna M, Carbone C, Flentje H, Green D, Maasikmets M, Marmureanu L, Minguillon MC, Prevot ASH, Gros V, Jayne J, Favez Oet al., 2019, The second ACTRIS inter-comparison (2016) for Aerosol Chemical Speciation Monitors (ACSM): Calibration protocols and instrument performance evaluations, AEROSOL SCIENCE AND TECHNOLOGY, ISSN: 0278-6826

Journal article

Green DC, Fuller GW, 2019, Evaluation of tire wear contribution to PM2.5 in urban environments, Atmosphere, Vol: 10

Vehicle-related particulate matter (PM) emissions may arise from both exhaust andnon-exhaust mechanisms, such as brake wear, tire wear, and road pavement abrasion, each ofwhich may be emitted directly and indirectly through resuspension of settled road dust. Severalresearchers have indicated that the proportion of PM2.5 attributable to vehicle traffic will increasingly come from non-exhaust sources. Currently, very little empirical data is available to characterize tire and road wear particles (TRWP) in the PM2.5 fraction. As such, this study was undertaken to quantify TRWP in PM2.5 at roadside locations in urban centers including London, Tokyo and Los Angeles, where vehicle traffic is an important contributor to ambient air PM. The samples were analyzed using validated chemical markers for tire tread polymer based on a pyrolysis technique. Results indicated that TRWP concentrations in the PM2.5 fraction were low, with averages ranging from < 0.004 to 0.10 g/m3, representing an average contribution to total PM2.5 of 0.27%. The TRWP levels in PM2.5 were significantly different between the three cities, with significant differences between London and Los Angeles and Tokyo and Los Angeles. There was no significant correlation between TRWP in PM2.5 and traffic count. This study provides an initial dataset to understand potential human exposure to airborne TRWP and the potential contribution of this non-exhaust emission source to total PM2.5.

Journal article

Warren E, Charlton-perez C, Kotthaus S, Marenco F, Ryder C, Johnson B, Green D, Lean H, Ballard S, Grimmond Set al., 2019, Observed aerosol characteristics to improve forward-modelled attenuated backscatter in urban areas, ATMOSPHERIC ENVIRONMENT, ISSN: 1352-2310

Numerical weather prediction (NWP) models often parameterise aerosols to reduce computational needs, while aiming to accurately capture their impact adequately. Increasingly, aerosols are monitored in-situ directly and/or indirectly (e.g. by automatic lidars and ceilometers, ALC). ALC measure the aerosol optical characteristic of attenuated backscatter. This can also be estimated using forward models that combine forecast aerosol and relative humidity to parameterise aerosol physical and optical characteristics. The aerFO is one such forward model, designed to use Met Office NWP model output and parameterisations from the MURK visibility scheme. Given the aerFO-MURK scheme link, assessing the aerFO and its output could therefore be used to inform future developments of the MURK scheme. To identify which parameterised physical and optical aerosol characteristics in the scheme are the most critical in urban settings, aerFO is driven with different in-situ aerosol observations at a background site in central London. Estimated attenuated backscatter is then assessed against ALC observations. It is shown that the original MURK scheme parameterisation underestimates the variance of both dry mean volume radius and total number concentration. Representing both the accumulation and coarse mode aerosols in the aerFO reduces the median bias error of estimated attenuated backscatter by 69.1%. Providing more realistic temporal (monthly to hourly) variability of relative mass for different species leads to little improvement, compared to using monthly climatological means. Numerical experiments show that having more realistic estimates of number concentration is more important than providing more accurate values of the dry mean volume radius for the accumulation mode. Hence, improving the parameterisations for number concentration should be a main focus for further development of the MURK scheme. To estimate aerosol attenuated backscatter, the aerFO requires an extinction to back

Journal article

Tremper AH, Font A, Priestman M, Hamad SH, Chung T-C, Pribadi A, Brown RJC, Goddard SL, Grassineau N, Petterson K, Kelly FJ, Green DCet al., 2018, Field and laboratory evaluation of a high time resolution x-ray fluorescence instrument for determining the elemental composition of ambient aerosols, ATMOSPHERIC MEASUREMENT TECHNIQUES, Vol: 11, Pages: 3541-3557, ISSN: 1867-1381

Journal article

McEneff GL, Richardson A, Webb T, Wood D, Murphy B, Irlam R, Mills J, Green D, Barron LPet al., 2018, Sorbent film-coated passive samplers for explosives vapour detection Part B, Deployment in Semi-Operational Environments and Alternative Applications, Vol: 8, Pages: 1-13, ISSN: 2045-2322

The application of new sorbent-film coated passive samplers for capture of bulk commercial and military explosives vapours in operationally relevant spaces such as luggage, rooms, vehicles and shipping containers is presented. Samplers were easily integrated with in-service detection technologies with little/no sample preparation required. Ethylene glycol dinitrate (EGDN) was detected within 4 h in a container holding a suitcase packed with 0.2 kg Perunit 28E. Within a 22,000 dm3 room, 1 kg of concealed Seguridad was detected within 24 h and in an adjoining room within 7 days. Exposed samplers also successfully captured components of 1 kg TNT after 72 h and 1 kg concealed Perunit 28E after 6 h in both a furnished room and a large, partially filled shipping container. For the latter, samplers captured detectable residues outside the container after 24 h and were stable during wet weather for 72 h. A one-week trial at three operationally relevant venues including a university, a theatre and a government building revealed a nuisance positive rate of <1.4% (n = 72). Finally, two alternative applications are presented for extraction of liquid samples and use a particulate contact swab showing flexibility for a range of different search activities.

Journal article

McEneff GL, Murphy B, Webb T, Wood D, Irlam R, Mills J, Green D, Barron LPet al., 2018, Sorbent film-coated passive samplers for explosives vapour detection Part A, Materials Optimisation and Integration with Analytical Technologies, Vol: 8, Pages: 1-13, ISSN: 2045-2322

A new thin-film passive sampler is presented as a low resource dependent and discrete continuous monitoring solution for explosives-related vapours. Using 15 mid-high vapour pressure explosives-related compounds as probes, combinations of four thermally stable substrates and six film-based sorbents were evaluated. Meta-aramid and phenylene oxide-based materials showed the best recoveries from small voids (~70%). Analysis was performed using liquid chromatography-high resolution accurate mass spectrometry which also enabled tentative identification of new targets from the acquired data. Preliminary uptake kinetics experiments revealed plateau concentrations on the device were reached between 3–5 days. Compounds used in improvised explosive devices, such as triacetone triperoxide, were detected within 1 hour and were stably retained by the sampler for up to 7 days. Sampler performance was consistent for 22 months after manufacture. Lastly, its direct integration with currently in-service explosives screening equipment including ion mobility spectrometry and thermal desorption mass spectrometry is presented. Following exposure to several open environments and targeted interferences, sampler performance was subsequently assessed and potential interferences identified. High-security building and area monitoring for concealed explosives using such cost-effective and discrete passive samplers can add extra assurance to search routines while minimising any additional burden on personnel or everyday site operation.

Journal article

Ots R, Heal MR, Young DE, Williams LR, Allan JD, Nemitz E, Di Marco C, Detournay A, Xu L, Ng NL, Coe H, Herndon SC, Mackenzie IA, Green DC, Kuenen JJP, Reis S, Vieno Met al., 2018, Modelling carbonaceous aerosol from residential solid fuel burning with different assumptions for emissions, ATMOSPHERIC CHEMISTRY AND PHYSICS, Vol: 18, Pages: 4497-4518, ISSN: 1680-7316

Journal article

Wooster MJ, Gaveau DLA, Salim MA, Zhang T, Xu W, Green DC, Huijnen V, Murdiyarso D, Gunawan D, Borchard N, Schirrmann M, Main B, Sepriando Aet al., 2018, New Tropical Peatland Gas and Particulate Emissions Factors Indicate 2015 Indonesian Fires Released Far More Particulate Matter (but Less Methane) than Current Inventories Imply, REMOTE SENSING, Vol: 10

Journal article

Ropkins K, DeFries TH, Pope F, Green DC, Kemper J, Kishan S, Fuller GW, Li H, Sidebottom J, Crilley LR, Kramer L, Bloss WJ, Stewart Hager Jet al., 2017, Evaluation of EDAR vehicle emissions remote sensing technology, Science of the Total Environment, Vol: 609, Pages: 1464-1474, ISSN: 0048-9697

Despite much work in recent years, vehicle emissions remain a significant contributor in many areas where air quality standards are under threat. Policy-makers are actively exploring options for next generation vehicle emission control and local fleet management policies, and new monitoring technologies to aid these activities. Therefore, we report here on findings from two separate but complementary blind evaluation studies of one new-to-market real-world monitoring option, HEAT LLC's Emission Detection And Reporting system or EDAR, an above-road open path instrument that uses Differential Absorption LIDAR to provide a highly sensitive and selective measure of passing vehicle emissions. The first study, by Colorado Department of Public Health and Environment and Eastern Research Group, was a simulated exhaust gas test exercise used to investigate the instrumental accuracy of the EDAR. Here, CO, NO, CH4 and C3H8 measurements were found to exhibit high linearity, low bias, and low drift over a wide range of concentrations and vehicle speeds. Instrument accuracy was high (R2 0.996 for CO, 0.998 for NO; 0.983 for CH4; and 0.976 for C3H8) and detection limits were 50 to 100 ppm for CO, 10 to 30 ppm for NO, 15 to 35 ppmC for CH4, and, depending on vehicle speed, 100 to 400 ppmC3 for C3H8. The second study, by the Universities of Birmingham and Leeds and King's College London, used the comparison of EDAR, on-board Portable Emissions Measurement System (PEMS) and car chaser (SNIFFER) system measurements collected under real-world conditions to investigate in situ EDAR performance. Given the analytical challenges associated with aligning these very different measurements, the observed agreements (e.g. EDAR versus PEMS R2 0.92 for CO/CO2; 0.97 for NO/CO2; ca. 0.82 for NO2/CO2; and, 0.94 for PM/CO2) were all highly encouraging and indicate that EDAR also provides a representative measure of vehicle emissions under real-world conditions.

Journal article

Dong S, Ochoa Gonzalez R, Harrison RM, Green D, North R, Fowler G, Weiss Det al., 2017, Isotopic signatures in atmospheric particulate matter suggest important contributions from recycled gasoline for lead and non-exhaust traffic sources for copper and zinc in aerosols in London, United Kingdom, ATMOSPHERIC ENVIRONMENT, ISSN: 1352-2310

The aim of this study was to improve our understanding of what controls the isotope composition of Cu, Zn and Pb in particulate matter (PM) in the urban environment and to develop these isotope systems as possible source tracers. To this end, isotope ratios (Cu, Zn and Pb) and trace element concentrations (Fe, Al, Cu, Zn, Sb, Ba, Pb, Cr, Ni and V) were determined in PM10 collected at two road sites with contrasting traffic densities in central London, UK, during two weeks in summer 2010, and in potential sources, including non-combustion traffic emissions (tires and brakes), road furniture (road paint, manhole cover and road tarmac surface) and road dust. The isotope signatures of other important sources (gasoline and exhaust emissions) were taken from previous published data. Iron, Ba and Sb were used as proxies for emissions derived from brake pads, and Ni, and V for emissions derived from fossil fuel oil. The isotopic composition of Pb (expressed using 206Pb/207Pb) ranged between 1.1137 and 1.1364. The isotope ratios of Cu and Zn expressed as δ65CuNIST976 and δ66ZnLyon ranged between -0.01‰ and +0.51‰ and between -0.21‰ and +0.33‰, respectively. We did not find significant differences in the isotope signatures in PM10 over the two weeks sampling period and between the two sites, suggesting similar sources for each metal at both sites despite their different traffic densities. The stable isotope composition of Pb suggests significant contribution from road dust resuspension and from recycled leaded gasoline. The Cu and Zn isotope signatures of tires, brakes and road dust overlap with those of PM10. The correlation between the enrichments of Sb, Cu, Ba and Fe in PM10 support the previously established hypothesis that Cu isotope ratios are controlled by non-exhaust traffic emission sources in urban environments (Ochoa Gonzalez et al., 2016). Analysis of the Zn isotope signatures in PM10 and possible sources at the two sites su

Journal article

Reyes-Villegas E, Green DC, Priestman M, Canonaco F, Coe H, Prevot ASH, Allan JDet al., 2016, Organic aerosol source apportionment in London 2013 with ME-2: exploring the solution space with annual and seasonal analysis, ATMOSPHERIC CHEMISTRY AND PHYSICS, Vol: 16, Pages: 15545-15559, ISSN: 1680-7316

Journal article

Camina N, Green DC, Kelly FJ, Mudway ISet al., 2016, LOCAL SOURCES RATHER THAN INTERACTIONS WITH OXIDISING CO-POLLUTANT GASES DETERMINE THE GEOGRAPHICAL AND SEASONAL VARIATION IN PARTICULATE MATTER OXIDATIVE POTENTIAL, Publisher: BMJ PUBLISHING GROUP, Pages: A149-A149, ISSN: 0040-6376

Conference paper

Balducci C, Green DC, Romagnoli P, Perilli M, Johansson C, Panteliadis P, Cecinato Aet al., 2016, Cocaine and cannabinoids in the atmosphere of Northern Europe cities, comparison with Southern Europe and wastewater analysis, ENVIRONMENT INTERNATIONAL, Vol: 97, Pages: 187-194, ISSN: 0160-4120

Journal article

Ots R, Vieno M, Allan JD, Reis S, Nemitz E, Young DE, Coe H, Di Marco C, Detournay A, Mackenzie IA, Green DC, Heal MRet al., 2016, Model simulations of cooking organic aerosol (COA) over the UK using estimates of emissions based on measurements at two sites in London, ATMOSPHERIC CHEMISTRY AND PHYSICS, Vol: 16, Pages: 13773-13789, ISSN: 1680-7316

Journal article

Wragg FPH, Fuller SJ, Freshwater R, Green DC, Kelly FJ, Kalberer Met al., 2016, An automated online instrument to quantify aerosol-bound reactive oxygen species (ROS) for ambient measurement and health-relevant aerosol studies, ATMOSPHERIC MEASUREMENT TECHNIQUES, Vol: 9, Pages: 4891-4900, ISSN: 1867-1381

Journal article

Twigg MM, Ilyinskaya E, Beccaceci S, Green DC, Jones MR, Langford B, Leeson SR, Lingard JJN, Pereira GM, Carter H, Poskitt J, Richter A, Ritchie S, Simmons I, Smith RI, Tang YS, Van Dijk N, Vincent K, Nemitz E, Vieno M, Braban CFet al., 2016, Impacts of the 2014-2015 Holuhraun eruption on the UK atmosphere, ATMOSPHERIC CHEMISTRY AND PHYSICS, Vol: 16, Pages: 11415-11431, ISSN: 1680-7316

Journal article

Ots R, Young DE, Vieno M, Xu L, Dunmore RE, Allan JD, Coe H, Williams LR, Herndon SC, Ng NL, Hamilton JF, Bergström R, Di Marco C, Nemitz E, Mackenzie IA, Kuenen JJP, Green DC, Reis S, Heal MRet al., 2016, Simulating secondary organic aerosol from missing diesel-related intermediate-volatility organic compound emissions during the Clean Air for London (ClearfLo) campaign, Atmospheric Chemistry and Physics Discussions, Vol: 2016, ISSN: 1680-7367

We present high-resolution atmospheric chemistry transport model (ACTM) simulations of secondary organic aerosol (SOA) formation over the UK for 2012. Our simulations include additional diesel-related intermediate volatility organic compound (IVOC) emissions derived directly from comprehensive field measurements at an urban background site in London during the 2012 Clean Air for London (ClearfLo) campaign. Our IVOC emissions are added proportionally to VOC emissions, as opposed to proportionally to primary organic aerosol (POA) as has been done by previous ACTM studies seeking to simulate the effects of these missing emissions. Modelled concentrations are evaluated against hourly and daily measurements of organic aerosol (OA) components derived from aerosol mass spectrometer (AMS) measurements also made during the ClearfLo campaign at three sites in the London area. Good hourly performance in comparison to the measurements was shown, giving confidence in the SOA prediction skill of the ACTM system used. According to the model simulations, diesel-related IVOCs can explain on average ∼30% of the annual SOA in and around London. Furthermore, the 90-th percentile of modelled daily SOA concentrations for the whole year is 3.8 μg m (more than 40% of which is produced from the missing diesel precursors), constituting a notable addition to total particulate matter. More measurements of these precursors (currently not included in official emissions inventories) is recommended. During the period of concurrent measurements, SOA concentrations at the Detling rural background location east of London were greater than at the central London location. The model shows that this was caused by an intense pollution plume with a strong gradient of imported SOA passing over the rural location. This demonstrates the value of modelling for supporting the interpretation of measurements taken at different sites or for short durations. -3

Journal article

Ots R, Young DE, Vieno M, Xu L, Dunmore RE, Allan JD, Coe H, Williams LR, Herndon SC, Ng NL, Hamilton JF, Bergstrom R, Di Marco C, Nemitz E, Mackenzie IA, Kuenen JJP, Green DC, Reis S, Heal MRet al., 2016, Simulating secondary organic aerosol from missing diesel-related intermediate-volatility organic compound emissions during the Clean Air for London (ClearfLo) campaign, ATMOSPHERIC CHEMISTRY AND PHYSICS, Vol: 16, Pages: 6453-6473, ISSN: 1680-7316

Journal article

Samoli E, Atkinson RW, Analitis A, Fuller GW, Green DC, Mudway I, Anderson HR, Kelly FJet al., 2016, Associations of short-term exposure to traffic-related air pollution with cardiovascular and respiratory hospital admissions in London, UK, Occupational and Environmental Medicine, ISSN: 1351-0711

Objectives There is evidence of adverse associations between short-term exposure to traffic-related pollution and health, but little is known about the relative contribution of the various sources and particulate constituents.Methods For each day for 2011–2012 in London, UK over 100 air pollutant metrics were assembled using monitors, modelling and chemical analyses. We selected a priori metrics indicative of traffic sources: general traffic, petrol exhaust, diesel exhaust and non-exhaust (mineral dust, brake and tyre wear). Using Poisson regression models, controlling for time-varying confounders, we derived effect estimates for cardiovascular and respiratory hospital admissions at prespecified lags and evaluated the sensitivity of estimates to multipollutant modelling and effect modification by season.Results For single day exposure, we found consistent associations between adult (15–64 years) cardiovascular and paediatric (0–14 years) respiratory admissions with elemental and black carbon (EC/BC), ranging from 0.56% to 1.65% increase per IQR change, and to a lesser degree with carbon monoxide (CO) and aluminium (Al). The average of past 7 days EC/BC exposure was associated with elderly (65+ years) cardiovascular admissions. Indicated associations were higher during the warm period of the year. Although effect estimates were sensitive to the adjustment for other pollutants they remained consistent in direction, indicating independence of associations from different sources, especially between diesel and petrol engines, as well as mineral dust.Conclusions Our results suggest that exhaust related pollutants are associated with increased numbers of adult cardiovascular and paediatric respiratory hospitalisations. More extensive monitoring in urban centres is required to further elucidate the associations.

Journal article

Atkinson RW, Samoli E, Analitis A, Fuller GW, Green DC, Anderson HR, Purdie E, Dunster C, Aitlhadj L, Kelly FJ, Mudway ISet al., 2016, Short-term associations between particle oxidative potential and daily mortality and hospital admissions in London, INTERNATIONAL JOURNAL OF HYGIENE AND ENVIRONMENTAL HEALTH, Vol: 219, Pages: 566-572, ISSN: 1438-4639

Background:Particulate matter (PM) from traffic and other sources has been associated with adverse health effects. One unifying theory is that PM, whatever its source, acts on the human body via their capacity to cause damaging oxidation reactions related to their content of pro-oxidants components. Few epidemiological studies have investigated particle oxidative potential (OP) metrics and health. We conducted a time series analysis to assess associations between daily particle OP measures and numbers of deaths and hospital admissions for cardiovascular and respiratory diseases.Methods:During 2011 and 2012 particles with an aerodynamic diameter less than 2.5 and 10 microns (PM2.5 and PM10 respectively) were collected daily on Partisol filters located at an urban background monitoring station in Central London. Particulate OP was assessed based on the capacity of the particles to oxidize ascorbate (OPAA) and glutathione (OPGSH) from a simple chemical model reflecting the antioxidant composition of human respiratory tract lining fluid. Particulate OP, expressed as % loss of antioxidant per μg of PM, was then multiplied by the daily concentrations of PM to derive the daily OP of PM mass concentrations (% loss per m3). Daily numbers of deaths and age- and cause-specific hospital admissions in London were obtained from national registries. Poisson regression accounting for seasonality and meteorology was used to estimate the percentage change in risk of death or admission associated with an interquartile increment in particle OP.Results:We found little evidence for adverse associations between OPAA and OPGSH and mortality. Associations with cardiovascular admissions were generally positive in younger adults and negative in older adults with confidence intervals including 0%. For respiratory admissions there was a trend, from positive to negative associations, with increasing age although confidence intervals generally included 0%.Conclusions:Our study, the first to an

Journal article

Samoli E, Atkinson RW, Analitis A, Fuller GW, Beddows D, Green DC, Mudway IS, Harrison RM, Anderson HR, Kelly FJet al., 2016, Differential health effects of short-term exposure to source-specific particles in London, U.K, Environment International, Vol: 97, Pages: 246-253, ISSN: 0160-4120

BackgroundThere is ample evidence of adverse associations between short-term exposure to ambient particle mass concentrations and health but little is known about the relative contribution from various sources.MethodsWe used air particle composition and number networks in London between 2011 and 2012 to derive six source-related factors for PM10 and four factors for size distributions of ultrafine particles (NSD). We assessed the associations of these factors, at pre-specified lags, with daily total, cardiovascular (CVD) and respiratory mortality and hospitalizations using Poisson regression. Relative risks and 95% confidence intervals (CI) were expressed as percentage change per interquartile range increment in source-factor mass or number concentration. We evaluated the sensitivity of associations to adjustment for multiple other factors and by season.ResultsWe found no evidence of associations between PM10 or NSD source-related factors and daily mortality, as the direction of the estimates were variable with 95% CI spanning 0%. Traffic-related PM10 and NSD displayed consistent associations with CVD admissions aged 15–64 years (1.01% (95%CI: 0.03%, 2.00%) and 1.04% (95%CI: − 0.62%, 2.72%) respectively) as did particles from background urban sources (0.36% for PM10 and 0.81% for NSD). Most sources were positively associated with pediatric (0–14 years) respiratory hospitalizations, with stronger evidence for fuel oil PM10 (3.43%, 95%CI: 1.26%, 5.65%). Our results did not suggest associations with cardiovascular admissions in 65 + or respiratory admissions in 15 + age groups. Effect estimates were generally robust to adjustment for other factors and by season.ConclusionsOur findings are broadly consistent with the growing evidence of the toxicity of traffic and combustion particles, particularly in relation to respiratory morbidity in children and cardiovascular morbidity in younger adults.

Journal article

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