294 results on '"Crilley, Leigh"'
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2. Quantification of within-vehicle exposure to NOx and particles: Variation with outside air quality, route choice and ventilation options
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Matthaios, Vasileios N., Kramer, Louisa J., Crilley, Leigh R., Sommariva, Roberto, Pope, Francis D., and Bloss, William J.
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- 2020
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3. Predicting real-time within-vehicle air pollution exposure with mass-balance and machine learning approaches using on-road and air quality data
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Matthaios, Vasileios N., primary, Knibbs, Luke D., additional, Kramer, Louisa J., additional, Crilley, Leigh R., additional, and Bloss, William J., additional
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- 2023
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4. Chemical Fate of Oils on Indoor Surfaces: Ozonolysis and Peroxidation
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Zhou, Zilin, primary, Crilley, Leigh R., additional, Ditto, Jenna C., additional, VandenBoer, Trevor C., additional, and Abbatt, Jonathan P. D., additional
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- 2023
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5. Impact of HO2 aerosol uptake on radical levels and O3 production during summertime in Beijing
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Dyson, Joanna E., primary, Whalley, Lisa K., additional, Slater, Eloise J., additional, Woodward-Massey, Robert, additional, Ye, Chunxiang, additional, Lee, James D., additional, Squires, Freya, additional, Hopkins, James R., additional, Dunmore, Rachel E., additional, Shaw, Marvin, additional, Hamilton, Jacqueline F., additional, Lewis, Alastair C., additional, Worrall, Stephen D., additional, Bacak, Asan, additional, Mehra, Archit, additional, Bannan, Thomas J., additional, Coe, Hugh, additional, Percival, Carl J., additional, Ouyang, Bin, additional, Hewitt, C. Nicholas, additional, Jones, Roderic L., additional, Crilley, Leigh R., additional, Kramer, Louisa J., additional, Acton, W. Joe F., additional, Bloss, William J., additional, Saksakulkrai, Supattarachai, additional, Xu, Jingsha, additional, Shi, Zongbo, additional, Harrison, Roy M., additional, Kotthaus, Simone, additional, Grimmond, Sue, additional, Sun, Yele, additional, Xu, Weiqi, additional, Yue, Siyao, additional, Wei, Lianfang, additional, Fu, Pingqing, additional, Wang, Xinming, additional, Arnold, Stephen R., additional, and Heard, Dwayne E., additional
- Published
- 2023
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6. Radical chemistry and ozone production at a UK coastal receptor site.
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Woodward-Massey, Robert, Sommariva, Roberto, Whalley, Lisa K., Cryer, Danny R., Ingham, Trevor, Bloss, William J., Ball, Stephen M., Cox, Sam, Lee, James D., Reed, Chris P., Crilley, Leigh R., Kramer, Louisa J., Bandy, Brian J., Forster, Grant L., Reeves, Claire E., Monks, Paul S., and Heard, Dwayne E.
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RADICALS (Chemistry) ,PEROXY radicals ,BUDGET ,MEDIAN (Mathematics) ,METROPOLITAN areas ,OZONE ,SEISMIC anisotropy - Abstract
OH, HO 2 , total and partially speciated RO 2 , and OH reactivity (kOH′) were measured during the July 2015 ICOZA (Integrated Chemistry of OZone in the Atmosphere) project that took place at a coastal site in north Norfolk, UK. Maximum measured daily OH, HO 2 and total RO 2 radical concentrations were in the range 2.6–17 × 10 6 , 0.75–4.2 × 10 8 and 2.3–8.0 × 10 8 molec. cm -3 , respectively. kOH′ ranged from 1.7 to 17.6 s -1 , with a median value of 4.7 s -1. ICOZA data were split by wind direction to assess differences in the radical chemistry between air that had passed over the North Sea (NW–SE sectors) and that over major urban conurbations such as London (SW sector). A box model using the Master Chemical Mechanism (MCMv3.3.1) was in reasonable agreement with the OH measurements, but it overpredicted HO 2 observations in NW–SE air in the afternoon by a factor of ∼ 2–3, although slightly better agreement was found for HO 2 in SW air (factor of ∼ 1.4–2.0 underprediction). The box model severely underpredicted total RO 2 observations in both NW–SE and SW air by factors of ∼ 8–9 on average. Measured radical and kOH′ levels and measurement–model ratios displayed strong dependences on NO mixing ratios, with the results suggesting that peroxy radical chemistry is not well understood under high-NO x conditions. The simultaneous measurement of OH, HO 2 , total RO 2 and kOH′ was used to derive experimental (i.e. observationally determined) budgets for all radical species as well as total RO x (i.e. OH + HO 2 + RO 2). In NW–SE air, the RO x budget could be closed during the daytime within experimental uncertainty, but the rate of OH destruction exceeded the rate of OH production, and the rate of HO 2 production greatly exceeded the rate of HO 2 destruction, while the opposite was true for RO 2. In SW air, the RO x budget analysis indicated missing daytime RO x sources, but the OH budget was balanced, and the same imbalances were found with the HO 2 and RO 2 budgets as in NW–SE air. For HO 2 and RO 2 , the budget imbalances were most severe at high-NO mixing ratios, and the best agreement between HO 2 and RO 2 rates of production and destruction rates was found when the RO 2 + NO rate coefficient was reduced by a factor of 5. A photostationary-steady-state (PSS) calculation underpredicted daytime OH in NW–SE air by ∼ 35 %, whereas agreement (∼ 15 %) was found within instrumental uncertainty (∼ 26 % at 2 σ) in SW air. The rate of in situ ozone production (P (O x)) was calculated from observations of RO x , NO and NO 2 and compared to that calculated from MCM-modelled radical concentrations. The MCM-calculated P (O x) significantly underpredicted the measurement-calculated P (O x) in the morning, and the degree of underprediction was found to scale with NO. [ABSTRACT FROM AUTHOR]
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- 2023
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7. Extreme Concentrations of Nitric Oxide Control Daytime Oxidation and Quench Nocturnal Oxidation Chemistry in Delhi during Highly Polluted Episodes
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Nelson, Beth S., Bryant, Daniel J., Alam, Mohammed S., Sommariva, Roberto, Bloss, William J., Newland, Mike J., Drysdale, Will S., Vaughan, Adam R., Acton, W. Joe F., Hewitt, C. Nicholas, Crilley, Leigh R., Swift, Stefan J., Edwards, Pete M., Lewis, Alastair C., Langford, Ben, Nemitz, Eiko, Shivani, Gadi, Ranu, Gurjar, Bhola R., Heard, Dwayne E., Whalley, Lisa K., Şahin, Ülkü A., Beddows, David C. S., Hopkins, James R., Lee, James D., Rickard, Andrew R., Hamilton, Jacqueline F., Nelson, Beth S., Bryant, Daniel J., Alam, Mohammed S., Sommariva, Roberto, Bloss, William J., Newland, Mike J., Drysdale, Will S., Vaughan, Adam R., Acton, W. Joe F., Hewitt, C. Nicholas, Crilley, Leigh R., Swift, Stefan J., Edwards, Pete M., Lewis, Alastair C., Langford, Ben, Nemitz, Eiko, Shivani, Gadi, Ranu, Gurjar, Bhola R., Heard, Dwayne E., Whalley, Lisa K., Şahin, Ülkü A., Beddows, David C. S., Hopkins, James R., Lee, James D., Rickard, Andrew R., and Hamilton, Jacqueline F.
- Abstract
Delhi, India, suffers from periods of very poor air quality, but little is known about the chemical production of secondary pollutants in this highly polluted environment. During the postmonsoon period in 2018, extremely high nighttime concentrations of NOx (NO and NO2) and volatile organic compounds (VOCs) were observed, with median NOx mixing ratios of ∼200 ppbV (maximum of ∼700 ppbV). A detailed chemical box model constrained to a comprehensive suite of speciated VOC and NOx measurements revealed very low nighttime concentrations of oxidants, NO3, O3, and OH, driven by high nighttime NO concentrations. This results in an atypical NO3 diel profile, not previously reported in other highly polluted urban environments, significantly perturbing nighttime radical oxidation chemistry. Low concentrations of oxidants and high nocturnal primary emissions coupled with a shallow boundary layer led to enhanced early morning photo-oxidation chemistry. This results in a temporal shift in peak O3 concentrations when compared to the premonsoon period (12:00 and 15:00 local time, respectively). This shift will likely have important implications on local air quality, and effective urban air quality management should consider the impacts of nighttime emission sources during the postmonsoon period.
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- 2023
8. Extensive field evidence for the release of HONO from the photolysis of nitrate aerosols
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Andersen, Simone T., primary, Carpenter, Lucy J., additional, Reed, Chris, additional, Lee, James D., additional, Chance, Rosie, additional, Sherwen, Tomás, additional, Vaughan, Adam R., additional, Stewart, Jordan, additional, Edwards, Pete M., additional, Bloss, William J., additional, Sommariva, Roberto, additional, Crilley, Leigh R., additional, Nott, Graeme J., additional, Neves, Luis, additional, Read, Katie, additional, Heard, Dwayne E., additional, Seakins, Paul W., additional, Whalley, Lisa K., additional, Boustead, Graham A., additional, Fleming, Lauren T., additional, Stone, Daniel, additional, and Fomba, Khanneh Wadinga, additional
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- 2023
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9. Development and validation of a new in situ technique to measure total gaseous chlorine in air
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Furlani, Teles C., primary, Ye, RenXi, additional, Stewart, Jordan, additional, Crilley, Leigh R., additional, Edwards, Peter M., additional, Kahan, Tara F., additional, and Young, Cora J., additional
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- 2023
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10. Emerging investigator series: An instrument to measure and speciate the total reactive nitrogen budget indoors: description and field measurements
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Crilley, Leigh, primary, Lao, Melodie, additional, Salehpoor, Leyla, additional, and Vandenboer, Trevor C., additional
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- 2023
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11. Indoor and Outdoor Air Quality Impacts of Cooking and Cleaning Emissions from a Commercial Kitchen
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Ditto, Jenna C., primary, Crilley, Leigh, additional, Lao, Melodie, additional, Vandenboer, Trevor C., additional, Abbatt, Jonathan, additional, and Chan, Arthur, additional
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- 2023
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12. Supplementary material to "Impact of HO2 aerosol uptake on radical levels and O3 production during summertime in Beijing"
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Dyson, Joanna E., primary, Whalley, Lisa K., additional, Slater, Eloise J., additional, Woodward-Massey, Robert, additional, Ye, Chunxiang, additional, Lee, James D., additional, Squires, Freya, additional, Hopkins, James R., additional, Dunmore, Rachel E., additional, Shaw, Marvin, additional, Hamilton, Jacqueline F., additional, Lewis, Alastair C., additional, Worrall, Stephen D., additional, Bacak, Asan, additional, Mehra, Archit, additional, Bannan, Thomas J., additional, Coe, Hugh, additional, Percival, Carl J., additional, Ouyang, Bin, additional, Hewitt, C. Nicholas, additional, Jones, Roderic L., additional, Crilley, Leigh R., additional, Kramer, Louisa J., additional, Acton, W. Joe F., additional, Bloss, William J., additional, Saksakulkrai, Supattarachai, additional, Xu, Jingsha, additional, Shi, Zongbo, additional, Harrison, Roy M., additional, Kotthaus, Simone, additional, Grimmond, Sue, additional, Sun, Yele, additional, Xu, Weiqi, additional, Yue, Siyao, additional, Wei, Lianfang, additional, Fu, Pingqing, additional, Wang, Xinming, additional, Arnold, Stephen R., additional, and Heard, Dwayne E., additional
- Published
- 2022
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13. Impact of HO2 aerosol uptake on radical levels and O3 production during summertime in Beijing
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Dyson, Joanna E., primary, Whalley, Lisa K., additional, Slater, Eloise J., additional, Woodward-Massey, Robert, additional, Ye, Chunxiang, additional, Lee, James D., additional, Squires, Freya, additional, Hopkins, James R., additional, Dunmore, Rachel E., additional, Shaw, Marvin, additional, Hamilton, Jacqueline F., additional, Lewis, Alastair C., additional, Worrall, Stephen D., additional, Bacak, Asan, additional, Mehra, Archit, additional, Bannan, Thomas J., additional, Coe, Hugh, additional, Percival, Carl J., additional, Ouyang, Bin, additional, Hewitt, C. Nicholas, additional, Jones, Roderic L., additional, Crilley, Leigh R., additional, Kramer, Louisa J., additional, Acton, W. Joe F., additional, Bloss, William J., additional, Saksakulkrai, Supattarachai, additional, Xu, Jingsha, additional, Shi, Zongbo, additional, Harrison, Roy M., additional, Kotthaus, Simone, additional, Grimmond, Sue, additional, Sun, Yele, additional, Xu, Weiqi, additional, Yue, Siyao, additional, Wei, Lianfang, additional, Fu, Pingqing, additional, Wang, Xinming, additional, Arnold, Stephen R., additional, and Heard, Dwayne E., additional
- Published
- 2022
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14. Characteristics of ultrafine particle sources and deposition rates in primary school classrooms
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Laiman, Rusdin, He, Congrong, Mazaheri, Mandana, Clifford, Samuel, Salimi, Farhad, Crilley, Leigh R., Megat Mokhtar, Megat Azman, and Morawska, Lidia
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- 2014
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15. Analysis of organic aerosols collected on filters by Aerosol Mass Spectrometry for source identification
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Crilley, Leigh R., Ayoko, Godwin A., and Morawska, Lidia
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- 2013
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16. Measurement report: Interpretation of wide-range particulate matter size distributions in Delhi
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Harrison, Roy M., Alam, Mohammed S., Beddows, David C.S., Bousiotis, Dimitrios, Shi, Zongbo, Crilley, Leigh R., Bloss, William, Brean, James, Khanna, Isha, and Verma, Rulan
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Atmospheric Science - Abstract
Delhi is one of the world's most polluted cities, with very high concentrations of airborne particulate matter. However, little is known about the factors controlling the characteristics of wide-range particle number size distributions. Here, new measurements are reported from three field campaigns conducted in winter and pre-monsoon and post-monsoon seasons at the Indian Institute of Technology campus in the south of the city. Particle number size distributions were measured simultaneously, using a scanning mobility particle sizer and a GRIMM optical particle monitor, covering 15 nm to >10 ?m diameter. The merged, wide-range size distributions were categorized into the following five size ranges: nucleation (15-20 nm), Aitken (20-100 nm), accumulation (100 nm-1 ?m), large fine (1-2.5 ?m), and coarse (2.5-10 ?m) particles. The ultrafine fraction (15-100 nm) accounts for about 52 % of all particles by number (PN10 is the total particle number from 15 nm to 10 ?m) but just 1 % by PM10 volume (PV10 is the total particle volume from 15 nm to 10 ?m). The measured size distributions are markedly coarser than most from other parts of the world but are consistent with earlier cascade impactor data from Delhi. Our results suggest substantial aerosol processing by coagulation, condensation, and water uptake in the heavily polluted atmosphere, which takes place mostly at nighttime and in the morning hours. Total number concentrations are highest in winter, but the mode of the distribution is largest in the post-monsoon (autumn) season. The accumulation mode particles dominate the particle volume in autumn and winter, while the coarse mode dominates in summer. Polar plots show a huge variation between both size fractions in the same season and between seasons for the same size fraction. The diurnal pattern of particle numbers is strongly reflective of a road traffic influence upon concentrations, especially in autumn and winter, although other sources, such as cooking and domestic heating, may influence the evening peak. There is a clear influence of diesel traffic at nighttime, when it is permitted to enter the city, and also indications in the size distribution data of a mode < 15 nm, which is probably attributable to CNG/LPG vehicles. New particle formation appears to be infrequent and is, in this dataset, limited to 1 d in the summer campaign. Our results reveal that the very high emissions of airborne particles in Delhi, particularly from traffic, determine the variation in particle number size distributions.
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- 2022
17. Elevated levels of chloramines and chlorine detected near an indoor sports complex.
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Angelucci, Andrea A., Crilley, Leigh R., Richardson, Rob, Valkenburg, Thalassa S. E., Monks, Paul S., Roberts, James M., Sommariva, Roberto, and VandenBoer, Trevor C.
- Abstract
Chloramines (NH
2 Cl, NHCl2 , and NCl3 ) are toxic compounds that can be created during the use of bleach-based disinfectants that contain hypochlorous acid (HOCl) and the hypochlorite ion (OCl− ) as their active ingredients. Chloramines can then readily transfer from the aqueous-phase to the gas-phase. Atmospheric chemical ionization mass spectrometry using iodide adduct chemistry (I-CIMS) made observations across two periods (2014 and 2016) at an urban background site on the University of Leicester campus (Leicester, UK). Both monochloramine (NH2 Cl) and molecular chlorine (Cl2 ) were detected and positively identified from calibrated mass spectra during both sampling periods and to our knowledge, this is the first detection of NH2 Cl outdoors. Mixing ratios of NH2 Cl reached up to 2.2 and 4.0 parts per billion by volume (ppbv), with median mixing ratios of 30 and 120 parts per trillion by volume (pptv) during the 2014 and 2016 sampling periods, respectively. Levels of Cl2 were observed to reach up to 220 and 320 pptv. Analysis of the NH2 Cl and Cl2 data pointed to the same local source, a nearby indoor sports complex with a swimming pool and a cleaning product storage shed. No appreciable levels of NHCl2 and NCl3 were observed outdoors, suggesting the indoor pool was not likely to be the primary source of the observed ambient chloramines, as prior measurements made in indoor pool atmospheres indicate that NCl3 would be expected to dominate. Instead, these observations point to indoor cleaning and/or cleaning product emissions as the probable source of NH2 Cl and Cl2 where the measured levels provide indirect evidence for substantial amounts transported from indoors to outdoors. Our upper estimate for total NH2 Cl emissions from the University of Leicester indoor sports complexes scaled for similar sports complexes across the UK is 3.4 × 105 ± 1.1 × 105 μg h−1 and 0.0017 ± 0.00034 Gg yr−1 , respectively. The Cl-equivalent emissions in HCl are only an order of magnitude less to those from hazardous waste incineration and iron and steel sinter production in the UK National Atmospheric Emissions Inventory (NAEI). [ABSTRACT FROM AUTHOR]- Published
- 2023
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18. Measurement report: Interpretation of wide-range particulate matter size distributions in Delhi
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Şahin, Ülkü Alver, primary, Harrison, Roy M., additional, Alam, Mohammed S., additional, Beddows, David C. S., additional, Bousiotis, Dimitrios, additional, Shi, Zongbo, additional, Crilley, Leigh R., additional, Bloss, William, additional, Brean, James, additional, Khanna, Isha, additional, and Verma, Rulan, additional
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- 2022
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19. Radical chemistry at a UK coastal receptor site – Part 2: experimental radical budgets and ozone production
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Woodward-Massey, Robert, primary, Sommariva, Roberto, additional, Whalley, Lisa K., additional, Cryer, Danny R., additional, Ingham, Trevor, additional, Bloss, William J., additional, Ball, Stephen M., additional, Lee, James D., additional, Reed, Chris P., additional, Crilley, Leigh R., additional, Kramer, Louisa J., additional, Bandy, Brian J., additional, Forster, Grant L., additional, Reeves, Claire E., additional, Monks, Paul S., additional, and Heard, Dwayne E., additional
- Published
- 2022
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20. Effectiveness of low-cost air quality monitors for identifying volcanic SO₂ and PM downwind from Masaya volcano, Nicaragua
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Whitty, Rachel, primary, Pfeffer, Melissa, additional, Ilyinskaya, Evgenia, additional, Roberts, Tjarda, additional, Schmidt, Anja, additional, Barsotti, Sara, additional, Strauch, Wilfried, additional, Crilley, Leigh, additional, Pope, Francis, additional, Bellanger, Harold, additional, Mendoza, Elvis, additional, Mather, Tamsin, additional, Liu, Emma, additional, Peters, Nial, additional, Taylor, Isabelle, additional, Francis, Hilary, additional, Hernández Leiva, Xochilt, additional, Lynch, Dave, additional, Nobert, Sébastien, additional, and Baxter, Peter, additional
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- 2022
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21. Assessing the effectiveness of low-cost air quality monitors for identifying volcanic SO2 and PM downwind from Masaya volcano, Nicaragua
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Whitty, Rachel C. W., primary, Pfeffer, Melissa A., additional, Ilyinskaya, Evgenia, additional, Roberts, Tjarda J., additional, Schmidt, Anja, additional, Barsotti, Sara, additional, Strauch, Wilfried, additional, Crilley, Leigh R., additional, Pope, Francis D., additional, Bellanger, Harold, additional, Mendoza, Elvis, additional, Mather, Tamsin A., additional, Liu, Emma J., additional, Peters, Nial, additional, Taylor, Isabelle A., additional, Francis, Hilary, additional, Hernández Leiva, Xochilt, additional, Lynch, Dave, additional, Norbert, Sebastien, additional, and Baxter, Peter, additional
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- 2022
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22. Is the ocean surface a source of nitrous acid (HONO) in the marine boundary layer?
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Crilley, Leigh R., primary, Kramer, Louisa J., additional, Pope, Francis D., additional, Reed, Chris, additional, Lee, James D., additional, Carpenter, Lucy J., additional, Hollis, Lloyd D. J., additional, Ball, Stephen M., additional, and Bloss, William J., additional
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- 2021
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23. Supplementary material to "Measurement Report: Interpretation of Wide Range Particulate Matter Size Distributions in Delhi"
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Şahin, Ülkü Alver, primary, Harrison, Roy M., additional, Alam, Mohammed S., additional, Beddows, David C. S., additional, Bousiotis, Dimitrios, additional, Shi, Zongbo, additional, Crilley, Leigh R., additional, Bloss, William, additional, Brean, James, additional, Khanna, Isha, additional, and Verma, Rulan, additional
- Published
- 2021
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24. Measurement Report: Interpretation of Wide Range Particulate Matter Size Distributions in Delhi
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Şahin, Ülkü Alver, primary, Harrison, Roy M., additional, Alam, Mohammed S., additional, Beddows, David C. S., additional, Bousiotis, Dimitrios, additional, Shi, Zongbo, additional, Crilley, Leigh R., additional, Bloss, William, additional, Brean, James, additional, Khanna, Isha, additional, and Verma, Rulan, additional
- Published
- 2021
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25. Author response
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Crilley, Leigh, primary
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- 2021
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26. PM1 composition and source apportionment at two sites in Delhi, India, across multiple seasons
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Reyes-Villegas, Ernesto, Panda, Upasana, Darbyshire, Eoghan, Cash, James M., Joshi, Rutambhara, Langford, Ben, Di Marco, Chiara F., Mullinger, Neil J., Alam, Mohammed S., Crilley, Leigh R., Rooney, Daniel J., Acton, W. Joe F., Drysdale, Will, Nemitz, Eiko, Flynn, Michael, Voliotis, Aristeidis, McFiggans, Gordon, Coe, Hugh, Lee, James, Hewitt, C. Nicholas, Heal, Mathew R., Gunthe, Sachin S., Mandal, Tuhin K., Gurjar, Bhola R., Shivani, Gadi, Ranu, Singh, Siddhartha, Soni, Vijay, and Allan, James D.
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aerosol mass spectrometry ,Source apportionment ,urban air quality ,air pollution ,positive matrix factorization ,megacities ,atmospheric aerosol ,Atmospheric Sciences ,PM1 - Abstract
Air pollution in urban environments has been shown to have a negative impact on air quality and human health, particularly in megacities. Over recent decades, Delhi, India, has suffered high atmospheric pollution, with significant particulate matter (PM) concentrations as a result of anthropogenic activities. Organic aerosols (OAs) are composed of thousands of different chemical species and are one of the main constituents of submicron particles. However, quantitative knowledge of OA composition, their sources and their processes in urban environments is still limited. This is important particularly in India, as Delhi is a massive, inhomogeneous conurbation, where we would expect the apportionment and concentrations to vary depending on where in Delhi the measurements/source apportionment is performed, indicating the need for multisite measurements. This study presents the first multisite analysis carried out in India over different seasons, with a focus on identifying OA sources. The measurements were taken during 2018 at two sites in Delhi, India. One site was located at the India Meteorological Department, New Delhi (ND). The other site was located at the Indira Gandhi Delhi Technical University for Women, Old Delhi (OD). Non-refractory submicron aerosol (NR-PM1) concentrations (ammonium, nitrate, sulfate, chloride and organic aerosols) of four aerosol mass spectrometers were analysed. Collocated measurements of volatile organic compounds, black carbon, NOx and CO were performed. Positive matrix factorisation (PMF) analysis was performed to separate the organic fraction, identifying a number of conventional factors: hydrocarbon-like OAs (HOAs) related to traffic emissions, biomass burning OAs (BBOAs), cooking OAs (COAs) and secondary OAs (SOAs). A composition-based estimate of PM1 is defined by combining black carbon (BC) and NR-PM1 (C-PM1= BC + NR-PM1). No significant difference was observed in C-PM1 concentrations between sites, OD (142 ± 117 µg m−3) compared to ND (123 ± 71 µg m3), from post-monsoon measurements. A wider variability was observed between seasons, where pre-monsoon and monsoon showed C-PM1 concentrations lower than 60 µg m−3. A seasonal variation in C-PM1 composition was observed; SO42- showed a high contribution over pre-monsoon and monsoon seasons, while NO3- and Cl− had a higher contribution in winter and post-monsoon. The main primary aerosol source was from traffic, which is consistent with the PMF analysis and Aethalometer model analysis. Thus, in order to reduce PM1 concentrations in Delhi through local emission controls, traffic emission control offers the greatest opportunity. PMF–aerosol mass spectrometer (AMS) mass spectra will help to improve future aerosol source apportionment studies. The information generated in this study increases our understanding of PM1 composition and OA sources in Delhi, India. Furthermore, the scientific findings provide significant information to strengthen legislation that aims to improve air quality in India.
- Published
- 2021
27. Evaluating the sensitivity of radical chemistry and ozone formation to ambient VOCs and NOₓ in Beijing
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Whalley, Lisa K., Slater, Eloise J., Woodward-Massey, Robert, Ye, Chunxiang, Lee, James D., Squires, Freya, Hopkins, James R., Dunmore, Rachel E., Shaw, Marvin, Hamilton, Jacqueline F., Lewis, Alastair C., Mehra, Archit, Worrall, Stephen D., Bacak, Asan, Bannan, Thomas J., Coe, Hugh, Percival, Carl J., Ouyang, Bin, Jones, Roderic L., Crilley, Leigh R., Kramer, Louisa J., Bloss, William J., Vu, Tuan, Kotthaus, Simone, Grimmond, Sue, Sun, Yele, Xu, Weiqi, Yue, Siyao, Ren, Lujie, Acton, W. Joe F., Hewitt, C. Nicholas, Wang, Xinming, Fu, Pingqing, and Heard, Dwayne E.
- Abstract
Measurements of OH, HO2, complex RO2 (alkene- and aromatic-related RO2) and total RO2 radicals taken during the integrated Study of AIR Pollution PROcesses in Beijing (AIRPRO) campaign in central Beijing in the summer of 2017, alongside observations of OH reactivity, are presented. The concentrations of radicals were elevated, with OH reaching up to 2.8×107moleculecm−3, HO2 peaking at 1×109moleculecm−3 and the total RO2 concentration reaching 5.5×109moleculecm−3. OH reactivity (k(OH)) peaked at 89 s−1 during the night, with a minimum during the afternoon of ≈22s−1 on average. An experimental budget analysis, in which the rates of production and destruction of the radicals are compared, highlighted that although the sources and sinks of OH were balanced under high NO concentrations, the OH sinks exceeded the known sources (by 15 ppbv h−1) under the very low NO conditions (
- Published
- 2021
28. Supplementary material to "Is the ocean surface a source of nitrous acid (HONO) in the marine boundary layer?"
- Author
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Crilley, Leigh, primary, Kramer, Louisa, additional, Pope, Francis, additional, Reed, Chris, additional, Lee, James, additional, Carpenter, Lucy, additional, Hollis, Lloyd, additional, Ball, Stephen, additional, and Bloss, William, additional
- Published
- 2021
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29. Is the ocean surface a source of nitrous acid (HONO) in the marine boundary layer?
- Author
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Crilley, Leigh, primary, Kramer, Louisa, additional, Pope, Francis, additional, Reed, Chris, additional, Lee, James, additional, Carpenter, Lucy, additional, Hollis, Lloyd, additional, Ball, Stephen, additional, and Bloss, William, additional
- Published
- 2021
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30. Chemical source profiles of fine particles for five different sources in Delhi
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Hama, Sarkawt, primary, Kumar, Prashant, additional, Alam, Mohammed S., additional, Rooney, Daniel J., additional, Bloss, William J., additional, Shi, Zongbo, additional, Harrison, Roy M., additional, Crilley, Leigh R., additional, Khare, Mukesh, additional, and Gupta, Sanjay Kumar, additional
- Published
- 2021
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31. Evaluating the sensitivity of radical chemistry and ozone formation to ambient VOCs and NOxin Beijing
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Whalley, Lisa K., Slater, Eloise J., Woodward-Massey, Robert, Ye, Chunxiang, Lee, James D., Squires, Freya, Hopkins, James R., Dunmore, Rachel E., Shaw, Marvin, Hamilton, Jacqueline F., Lewis, Alastair C., Mehra, Archit, Worrall, Stephen D., Bacak, Asan, Bannan, Thomas J., Coe, Hugh, Percival, Carl J., Ouyang, Bin, Jones, Roderic L., Crilley, Leigh R., Kramer, Louisa J., Bloss, William J., Vu, Tuan, Kotthaus, Simone, Grimmond, Sue, Sun, Yele, Xu, Weiqi, Yue, Siyao, Ren, Lujie, Joe, W., Nicholas Hewitt, C., Wang, Xinming, Fu, Pingqing, Heard, Dwayne E., Whalley, Lisa K., Slater, Eloise J., Woodward-Massey, Robert, Ye, Chunxiang, Lee, James D., Squires, Freya, Hopkins, James R., Dunmore, Rachel E., Shaw, Marvin, Hamilton, Jacqueline F., Lewis, Alastair C., Mehra, Archit, Worrall, Stephen D., Bacak, Asan, Bannan, Thomas J., Coe, Hugh, Percival, Carl J., Ouyang, Bin, Jones, Roderic L., Crilley, Leigh R., Kramer, Louisa J., Bloss, William J., Vu, Tuan, Kotthaus, Simone, Grimmond, Sue, Sun, Yele, Xu, Weiqi, Yue, Siyao, Ren, Lujie, Joe, W., Nicholas Hewitt, C., Wang, Xinming, Fu, Pingqing, and Heard, Dwayne E.
- Abstract
Measurements of OH, HO2, complex RO2 (alkene-and aromatic-related RO2) and total RO2 radicals taken during the integrated Study of AIR Pollution PROcesses in Beijing (AIRPRO) campaign in central Beijing in the summer of 2017, alongside observations of OH reactivity, are presented. The concentrations of radicals were elevated, with OH reaching up to 2:8 × 107 molecule cm-3, HO2 peaking at 1 × 109 molecule cm-3 and the total RO2 concentration reaching 5:5×109 molecule cm-3. OH reactivity (k.OH/) peaked at 89 s-1 during the night, with a minimum during the afternoon of 22s-1 on average. An experimental budget analysis, in which the rates of production and destruction of the radicals are compared, highlighted that although the sources and sinks of OH were balanced under high NO concentrations, the OH sinks exceeded the known sources (by 15 ppbvh-1) under the very low NO conditions (< 0:5ppbv) experienced in the afternoons, demonstrating a missing OH source consistent with previous studies under high volatile organic compound (VOC) emissions and low NO loadings. Under the highest NO mixing ratios (104 ppbv), the HO2 production rate exceeded the rate of destruction by 50ppbvh-1, whilst the rate of destruction of total RO2 exceeded the production by the same rate, indicating that the net propagation rate of RO2 to HO2 may be substantially slower than assumed. If just 10 % of the RO2 radicals propagate to HO2 upon reaction with NO, the HO2 and RO2 budgets could be closed at high NO, but at low NO this lower RO2 to HO2 propagation rate revealed a missing RO2 sink that was similar in magnitude to the missing OH source. A detailed box model that incorporated the latest Master Chemical Mechanism (MCM3.3.1) reproduced the observed OH concentrations well but over-predicted the observed HO2 under low concentrations of NO (< 1ppbv) and under-predicted RO2 (both the complex RO2 fraction and other RO2 types which we classify as simple RO2) most significantly at the highest NO concent
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- 2021
32. Evaluating the sensitivity of radical chemistry and ozone formation to ambient VOCs and NOx in Beijing
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Whalley, Lisa, Slater, Eloise, Woodward-Massey, Robert, Ye, Chunxiang, Lee, James D., Squires, Freya, Hopkins, James R., Dunmore, Rachel E., Shaw, Marvin, Hamilton, Jacqueline F., Lewis, Alastair C., Mehra, Archit, Worrall, Stephen David, Bacak, Asan, Bannan, Thomas J., Coe, Hugh, Ouyang, Bin, Jones, Roderic L., Crilley, Leigh R., Kramer, Louisa J., Bloss, William J., Vu, Tuan, Kotthaus, Simone, Grimmond, Sue, Sun, Yele, Xu, Weiqi, Yue, Siyao, Ren, Lujie, Acton, W Joe F, Hewitt, C N, Wang, Xinming, Fu, Pingqing, Heard, Dwayne E., Whalley, Lisa, Slater, Eloise, Woodward-Massey, Robert, Ye, Chunxiang, Lee, James D., Squires, Freya, Hopkins, James R., Dunmore, Rachel E., Shaw, Marvin, Hamilton, Jacqueline F., Lewis, Alastair C., Mehra, Archit, Worrall, Stephen David, Bacak, Asan, Bannan, Thomas J., Coe, Hugh, Ouyang, Bin, Jones, Roderic L., Crilley, Leigh R., Kramer, Louisa J., Bloss, William J., Vu, Tuan, Kotthaus, Simone, Grimmond, Sue, Sun, Yele, Xu, Weiqi, Yue, Siyao, Ren, Lujie, Acton, W Joe F, Hewitt, C N, Wang, Xinming, Fu, Pingqing, and Heard, Dwayne E.
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- 2021
33. In situ ozone production is highly sensitive to volatile organic compounds in Delhi, India
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Nelson, Beth S., Stewart, Gareth J., Drysdale, Will S., Newland, Mike J., Vaughan, Adam R., Dunmore, Rachel E., Edwards, Pete M., Lewis, Alastair C., Hamilton, Jacqueline F., Acton, W. Joe, Hewitt, C. Nicholas, Crilley, Leigh R., Alam, Mohammed S., Şahin, Ülkü A., Beddows, David C.S., Bloss, William J., Slater, Eloise, Whalley, Lisa K., Heard, Dwayne E., Cash, James M., Langford, Ben, Nemitz, Eiko, Sommariva, Roberto, Cox, Sam, Gadi, Ranu, Gurjar, Bhola R., Hopkins, James R., Rickard, Andrew R., Lee, James D., Nelson, Beth S., Stewart, Gareth J., Drysdale, Will S., Newland, Mike J., Vaughan, Adam R., Dunmore, Rachel E., Edwards, Pete M., Lewis, Alastair C., Hamilton, Jacqueline F., Acton, W. Joe, Hewitt, C. Nicholas, Crilley, Leigh R., Alam, Mohammed S., Şahin, Ülkü A., Beddows, David C.S., Bloss, William J., Slater, Eloise, Whalley, Lisa K., Heard, Dwayne E., Cash, James M., Langford, Ben, Nemitz, Eiko, Sommariva, Roberto, Cox, Sam, Gadi, Ranu, Gurjar, Bhola R., Hopkins, James R., Rickard, Andrew R., and Lee, James D.
- Abstract
The Indian megacity of Delhi suffers from some of the poorest air quality in the world. While ambient NO2 and particulate matter (PM) concentrations have received considerable attention in the city, high ground-level ozone (O3) concentrations are an often overlooked component of pollution. O3 can lead to significant ecosystem damage and agricultural crop losses, and adversely affect human health. During October 2018, concentrations of speciated non-methane hydrocarbon volatile organic compounds (C2–C13), oxygenated volatile organic compounds (o-VOCs), NO, NO2, HONO, CO, SO2, O3, and photolysis rates, were continuously measured at an urban site in Old Delhi. These observations were used to constrain a detailed chemical box model utilising the Master Chemical Mechanism v3.3.1. VOCs and NOx (NO + NO2) were varied in the model to test their impact on local O3 production rates, P(O3), which revealed a VOC-limited chemical regime. When only NOx concentrations were reduced, a significant increase in P(O3) was observed; thus, VOC co-reduction approaches must also be considered in pollution abatement strategies. Of the VOCs examined in this work, mean morning P(O3) rates were most sensitive to monoaromatic compounds, followed by monoterpenes and alkenes, where halving their concentrations in the model led to a 15.6 %, 13.1 %, and 12.9 % reduction in P(O3), respectively. P(O3) was not sensitive to direct changes in aerosol surface area but was very sensitive to changes in photolysis rates, which may be influenced by future changes in PM concentrations. VOC and NOx concentrations were divided into emission source sectors, as described by the Emissions Database for Global Atmospheric Research (EDGAR) v5.0 Global Air Pollutant Emissions and EDGAR v4.3.2_VOC_spec inventories, allowing for the impact of individual emission sources on P(O3) to be investigated. Reducing road transport emissions only, a common strategy in air pollution abatement strategies worldwide, was found to inc
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- 2021
34. In situ Ozone Production is highly sensitive to Volatile Organic Compounds in the Indian Megacity of Delhi
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Nelson, B, Stewart, Gareth, Drysdale, W.S., Newland, Mike, Vaughan, Adam, Dunmore, Rachel, Edwards, Pete, Lewis, Alastair C., Hamilton, Jacqueline F., Acton, Joe, Hewitt, C N, Crilley, Leigh, Alam, Mohammed Salim, Sahin, Ulku, Beddows, David, Bloss, William, Slater, Eloise, Whalley, Lisa, Heard, Dwayne, Cash, James, Langford, Ben, Nemitz, Eiko, Sommariva, Roberto, Cox, Sam, Shivani, Gadi, Ranu, Gurjar, Bhola, Hopkins, James R., Rickard, Andrew, Lee, James, Nelson, B, Stewart, Gareth, Drysdale, W.S., Newland, Mike, Vaughan, Adam, Dunmore, Rachel, Edwards, Pete, Lewis, Alastair C., Hamilton, Jacqueline F., Acton, Joe, Hewitt, C N, Crilley, Leigh, Alam, Mohammed Salim, Sahin, Ulku, Beddows, David, Bloss, William, Slater, Eloise, Whalley, Lisa, Heard, Dwayne, Cash, James, Langford, Ben, Nemitz, Eiko, Sommariva, Roberto, Cox, Sam, Shivani, Gadi, Ranu, Gurjar, Bhola, Hopkins, James R., Rickard, Andrew, and Lee, James
- Abstract
The Indian megacity of Delhi suffers from some of the poorest air quality in the world. While ambient NO2 and particulate matter (PM) concentrations have received considerable attention in the city, high ground level ozone (O3) concentrations are an often overlooked component of pollution. O3 can lead to significant ecosystem damage, agricultural crop losses, and adversely affect human health. During October 2018, concentrations of speciated non-methane hydrocarbons volatile organic compounds (C2 – C13), oxygenated volatile organic compounds (o-VOCs), NO, NO2, HONO, CO, SO2, O3, and photolysis rates, were continuously measured at an urban site in Old Delhi. These observations were used to constrain a detailed chemical box model utilising the Master Chemical Mechanism v3.3.1. VOCs and NOx (NO + NO2) were varied in the model to test their impact on local O3 production rates, P(O3), which revealed a VOC-limited chemical regime. When only NOx concentrations were reduced, a significant increase in P(O3) was observed, thus VOC co-reduction approaches must also be considered in pollution abatement strategies. Of the VOCs examined in this work, mean morning P(O3) rates were most sensitive to monoaromatic compounds, followed by monoterpenes and alkenes, where halving their concentrations in the model led to a 15.6 %, 13.1 % and 12.9 % reduction in P(O3), respectively. P(O3) was not sensitive to direct changes in aerosol surface area but was very sensitive to changes in photolysis rates, which may be influenced by future changes in PM concentrations. VOC and NOx concentrations were divided into emission source sectors, as described by the EDGAR v5.0 Global Air Pollutant Emissions and EDGAR v4.3.2_VOC_spec inventories, allowing for the impact of individual emission sources on P(O3) to be investigated. Reducing road transport emissions only, a common strategy in air pollution abatement strategies worldwide, was found to increase P(O3), even when the source was removed in its en
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- 2021
35. Interference from alkenes in chemiluminescent NOx measurements
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Alam, Mohammed S., Crilley, Leigh R., Lee, James D., Kramer, Louisa J., Pfrang, Christian, Vázquez-Moreno, Mónica, Ródenas, Milagros, Muñoz, Amalia, and Bloss, William J.
- Abstract
Nitrogen oxides (NOx=NO+NO2) are critical intermediates in atmospheric chemistry and air pollution. NOx levels control the cycling and hence abundance of the primary atmospheric oxidants OH and NO3 and regulate the ozone production which results from the degradation of volatile organic compounds (VOCs) in the presence of sunlight. They are also atmospheric pollutants, and NO2 is commonly included in air quality objectives and regulations. NOx levels also affect the production of the nitrate component of secondary aerosol particles and other pollutants, such as the lachrymator peroxyacetyl nitrate (PAN). The accurate measurement of NO and NO2 is therefore crucial for air quality monitoring and understanding atmospheric composition. The most commonly used approach for the measurement of NO is the chemiluminescent detection of electronically excited NO2 (NO2∗) formed from the NO + O3 reaction within the NOx analyser. Alkenes, ubiquitous in the atmosphere from biogenic and anthropogenic sources, also react with ozone to produce chemiluminescence and thus may contribute to the measured NOx signal. Their ozonolysis reaction may also be sufficiently rapid that their abundance in conventional instrument background cycles, which also utilises the reaction with ozone, differs from that in the measurement cycle such that the background subtraction is incomplete, and an interference effect results. This interference has been noted previously, and indeed, the effect has been used to measure both alkenes and ozone in the atmosphere. Here we report the results of a systematic investigation of the response of a selection of commercial NOx monitors to a series of alkenes. These NOx monitors range from systems used for routine air quality monitoring to atmospheric research instrumentation. The species-investigated range was from short-chain alkenes, such as ethene, to the biogenic monoterpenes. Experiments were performed in the European PHOtoREactor (EUPHORE) to ensure common calibration and samples for the monitors and to unequivocally confirm the alkene levels present (via Fourier transform infrared spectroscopy – FTIR). The instrument interference responses ranged from negligible levels up to 11 %, depending upon the alkene present and conditions used (e.g. the presence of co-reactants and differing humidity). Such interferences may be of substantial importance for the interpretation of ambient NOx data, particularly for high VOC, low NOx environments such as forests or indoor environments where alkene abundance from personal care and cleaning products may be significant.
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- 2020
36. Observations of speciated isoprene nitrates in Beijing: implications for isoprene chemistry
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Reeves, Claire E., primary, Mills, Graham P., additional, Whalley, Lisa K., additional, Acton, W. Joe F., additional, Bloss, William J., additional, Crilley, Leigh R., additional, Grimmond, Sue, additional, Heard, Dwayne E., additional, Hewitt, C. Nicholas, additional, Hopkins, James R., additional, Kotthaus, Simone, additional, Kramer, Louisa J., additional, Jones, Roderic L., additional, Lee, James D., additional, Liu, Yanhui, additional, Ouyang, Bin, additional, Slater, Eloise, additional, Squires, Freya, additional, Wang, Xinming, additional, Woodward-Massey, Robert, additional, and Ye, Chunxiang, additional
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- 2021
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37. Enhanced wintertime oxidation of VOCs via sustained radical sources in the urban atmosphere
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Sommariva, Roberto, primary, Crilley, Leigh R., additional, Ball, Stephen M., additional, Cordell, Rebecca L., additional, Hollis, Lloyd D.J., additional, Bloss, William J., additional, and Monks, Paul S., additional
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- 2021
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38. Non-Woven Materials for Cloth-Based Face Mask Inserts: Relationship Between Material Properties and Sub-Micron Aerosol Filtration
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Crilley, Leigh R., primary, Angelucci, Andrea, primary, Malile, Brian, primary, Young, Cora J., primary, VandenBoer, Trevor C., primary, and Chen, Jennifer, primary
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- 2021
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39. Importance of Meteorology and Chemistry in Determining Air Pollutant Levels During COVID-19 Lockdown in Indian Cities
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Crilley, Leigh, primary, Iranpour, Yashar, primary, and Young, Cora J., primary
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- 2021
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40. Evaluating the sensitivity of radical chemistry and ozone formation to ambient VOCs and NOx in Beijing
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Whalley, Lisa, Slater, Eloise, Woodward-Massey, Robert, Ye, Chunxiang, Lee, James D., Squires, Freya, Hopkins, James R., Dunmore, Rachel E., Marvin David Shaw, Hamilton, Jacqueline F., Lewis, Alastair C., Mehra, Archit, Worrall, Stephen David, Bacak, Asan, Bannan, Thomas J., Coe, Hugh, Ouyang, Bin, Jones, Roderic L., Crilley, Leigh R., Kramer, Louisa J., Bloss, William J., Vu, Tuan, Kotthaus, Simone, Grimmond, Sue, Sun, Yele, Xu, Weiqi, Yue, Siyao, Ren, Lujie, Acton, W. Joe F., Hewitt, C. N., Wang, Xinming, Fu, Pingqing, and Heard, Dwayne E.
- Abstract
Measurements of OH, HO2, RO2-complex (alkene and aromatic-related RO2) and total RO2 radicals taken during the AIRPRO campaign in central Beijing in the summer of 2017, alongside observations of OH reactivity are presented. The concentrations of radicals were elevated with OH reaching up to 2.8 × 107 molecule cm−3, HO2 peaked at 1 × 109 molecule cm−3 and the total RO2 concentration reached 5.5 × 109 molecule cm−3. OH reactivity (k(OH)) peaked at 89 s−1 during the night, with a minimum during the afternoons of ~ 22 s−1 on average. An experimental budget analysis, in which the rates of production and destruction of the radicals are compared, highlighted that although the sources and sinks of OH were balanced under high NO concentrations, the OH sinks exceeded the known sources (by 15 ppbv hr−1) under the very low NO conditions (2 production rate exceeded the rate of destruction by ~ 50 ppbv hr−1, whilst the rate of destruction of total-RO2 exceeded the production by the same rate indicating that the net propagation rate of RO2 to HO2 may be substantially slower than assumed. If just 10 % of the RO2 radicals propagate to HO2 upon reaction with NO, the HO2 and RO2 budgets could be closed at high NO, but at low NO this lower RO2 to HO2 propagation rate revealed a missing RO2 sink that was similar in magnitude to the missing OH source. A detailed box model that incorporated the latest MCM chemical mechanism (MCM3.3.1) reproduced the observed OH concentrations well, but over-predicted the observed HO2 under low concentrations of NO (2 (both the complex-RO2 fraction and other RO2 types which we classify as simple-RO2) most significantly at the highest NO concentrations. The model also under-predicted the observed k(OH) consistently by ~ 10 s−1 across all NOx levels highlighting that the good agreement for OH was fortuitous due to a cancellation of missing OH source and sink terms in its budget. Including heterogeneous loss of HO2 to aerosol surfaces did reduce the modelled HO2 concentrations in-line with the observations, but only at NO mixing ratios 2 concentration on several mornings when the Cl atom concentration was calculated to exceed 1 × 104 atoms cm−3 and could reconcile the modelled and measured RO2 concentrations at these times. However, on other mornings, when the Cl atom concentration was lower, large under-predictions in total RO2 remained. Furthermore, the inclusion of Cl atom chemistry did not enhance the modelled RO2 beyond the first few hours after sunrise and so was unable to resolve the modelled under-prediction in RO2 observed at other times of the day. Model scenarios, in which missing VOC reactivity was included as an additional reaction that converted OH to RO2, highlighted that the modelled OH, HO2 and RO2 concentrations were sensitive to the choice of RO2 product. The level of modelled to measured agreement for HO2 and RO2 (both complex and simple) could be improved if the missing OH reactivity formed a larger RO2 species that was able to undergo reaction with NO, followed by isomerisation reactions reforming other RO2 species, before eventually generating HO2. In this work an α-pinene-derived RO2 species was used as an example. In this simulation, consistent with the experimental budget analysis, the model underestimated the observed OH indicating a missing OH source. The model uncertainty, with regards to the types of RO2 species present and the radicals they form upon reaction with NO (HO2 directly or another RO2 species), leads to over an order of magnitude less O3 production calculated from the predicted peroxy radicals than calculated from the observed peroxy radicals at the highest NO concentrations. This demonstrates the rate at which the larger RO2 species propagate to HO2 or to another RO2 or indeed to OH needs to be understood to accurately simulate the rate of ozone production in environments such as Beijing where large multifunctional VOCs are likely present.
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- 2020
41. A comparison of PM2.5-bound polycyclic aromatic hydrocarbons in summer Beijing (China) and Delhi (India)
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Elzein, Atallah, Stewart, Gareth J., Swift, Stefan J., Nelson, Beth S., Crilley, Leigh R., Alam, Mohammed S., Reyes-Villegas, Ernesto, Gadi, Ranu, Harrison, Roy M., Hamilton, Jacqueline F., and Lewis, Alastair C.
- Abstract
Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous pollutants in air, soil, and water and are known to have harmful effects on human health and the environment. The diurnal and nocturnal variations of 17 PAHs in ambient particle-bound PAHs were measured in urban Beijing (China) and Delhi (India) during the summer season using gas-chromatography–quadrupole time-of-flight mass spectrometry (GC-Q-TOF-MS). The mean concentration of particles less than 2.5 µm (PM2.5) observed in Delhi was 3.6 times higher than in Beijing during the measurement period in both the daytime and night-time. In Beijing, the mean concentration of the sum of the 17 PAHs (∑17 PAHs) was 8.2 ± 5.1 ng m−3 in daytime, with the highest contribution from indeno[1,2,3-cd]pyrene (12 %), while at night-time the total PAHs was 7.2 ± 2.0 ng m−3, with the largest contribution from benzo[b]fluoranthene (14 %). In Delhi, the mean ∑17 PAHs was 13.6 ± 5.9 ng m−3 in daytime and 22.7 ± 9.4 ng m−3 at night-time, with the largest contribution from indeno[1,2,3-cd]pyrene in both the day (17 %) and night (20 %). Elevated mean concentrations of total PAHs in Delhi observed at night were attributed to emissions from vehicles and biomass burning and to meteorological conditions leading to their accumulation from a stable and low atmospheric boundary layer. Local emission sources were typically identified as the major contributors to total measured PAHs in both cities. Major emission sources were characterized based on the contribution from each class of PAHs, with the four-, five- and six-ring PAHs accounting ∼ 95 % of the total PM2.5-bound PAHs mass in both locations. The high contribution of five-ring PAHs to total PAH concentration in summer Beijing and Delhi suggests a high contribution from petroleum combustion. In Delhi, a high contribution from six-ring PAHs was observed at night, suggesting a potential emission source from the combustion of fuel and oil in power generators, widely used in Delhi. The lifetime excess lung cancer risk (LECR) was calculated for Beijing and Delhi, with the highest estimated risk attributed to Delhi (LECR = 155 per million people), which is 2.2 times higher than the Beijing risk assessment value (LECR = 70 per million people). Finally, we have assessed the emission control policies in each city and identified those major sectors that could be subject to mitigation measures.
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- 2020
42. Elevated levels of OH observed in haze events during wintertime in central Beijing
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Slater, Eloise, Whalley, Lisa K., Woodward-Massey, Robert, Ye, Chunxiang, Lee, James D., Squires, Freja, Hopkins, James R., Dunmore, Rachel E., Shaw, Marvin, Hamilton, Jacqueline F., Lewis, Alastair C., Crilley, Leigh R., Kramer, Louisa J., Bloss, William J., Vu, Tuan, Sun, Yele, Xu, Weiqi, Yue, Siyao, Ren, Lujie, Acton, W. Joe F., Hewitt, C N, Wang, Xinming, Fu, Pingqing, Heard, Dwayne E., Slater, Eloise, Whalley, Lisa K., Woodward-Massey, Robert, Ye, Chunxiang, Lee, James D., Squires, Freja, Hopkins, James R., Dunmore, Rachel E., Shaw, Marvin, Hamilton, Jacqueline F., Lewis, Alastair C., Crilley, Leigh R., Kramer, Louisa J., Bloss, William J., Vu, Tuan, Sun, Yele, Xu, Weiqi, Yue, Siyao, Ren, Lujie, Acton, W. Joe F., Hewitt, C N, Wang, Xinming, Fu, Pingqing, and Heard, Dwayne E.
- Abstract
Wintertime in situ measurements of OH, HO2 and RO2 radicals and OH reactivity were made in central Beijing during November and December 2016. Exceptionally elevated NO was observed on occasions, up to ∼250 ppbv. The daily maximum mixing ratios for radical species varied significantly day-to-day over the ranges 1–8×106 cm−3 (OH), 0.2–1.5×108 cm−3 (HO2) and 0.3–2.5×108 cm−3 (RO2). Averaged over the full observation period, the mean daytime peak in radicals was 2.7×106, 0.39×108 and 0.88×108 cm−3 for OH, HO2 and total RO2, respectively. The main daytime source of new radicals via initiation processes (primary production) was the photolysis of HONO (∼83 %), and the dominant termination pathways were the reactions of OH with NO and NO2, particularly under polluted haze conditions. The Master Chemical Mechanism (MCM) v3.3.1 operating within a box model was used to simulate the concentrations of OH, HO2 and RO2. The model underpredicted OH, HO2 and RO2, especially when NO mixing ratios were high (above 6 ppbv). The observation-to-model ratio of OH, HO2 and RO2 increased from ∼1 (for all radicals) at 3 ppbv of NO to a factor of ∼3, ∼20 and ∼91 for OH, HO2 and RO2, respectively, at ∼200 ppbv of NO. The significant underprediction of radical concentrations by the MCM suggests a deficiency in the representation of gas-phase chemistry at high NOx. The OH concentrations were surprisingly similar (within 20 % during the day) in and outside of haze events, despite j(O1D) decreasing by 50 % during haze periods. These observations provide strong evidence that gas-phase oxidation by OH can continue to generate secondary pollutants even under high-pollution episodes, despite the reduction in photolysis rates within haze.
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- 2020
43. A boron dipyrromethene (BODIPY) based probe for selective passive sampling of atmospheric nitrous acid (HONO) indoors
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Nodeh-Farahani, Danial, primary, Bentley, Jordan N., additional, Crilley, Leigh R., additional, Caputo, Christopher B., additional, and VandenBoer, Trevor C., additional
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- 2021
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44. Importance of meteorology and chemistry in determining air pollutant levels during COVID-19 lockdown in Indian cities
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Crilley, Leigh R., primary, Iranpour, Yashar E., additional, and Young, Cora J., additional
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- 2021
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45. Insights into air pollution chemistry and sulphate formation from nitrous acid (HONO) measurements during haze events in Beijing
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Bloss, William J., primary, Kramer, Louisa, additional, Crilley, Leigh R., additional, Vu, Tuan, additional, Harrison, Roy M., additional, Shi, Zongbo, additional, Lee, James D., additional, Squires, Freya A., additional, Whalley, Lisa K., additional, Slater, Eloise, additional, Woodward-Massey, Robert, additional, Ye, Chunxiang, additional, Heard, Dwayne E., additional, Tong, Shengrui, additional, Hou, Siqi, additional, Sun, Yele, additional, Xu, Jingsha, additional, Wei, Lianfang, additional, and Fu, Pingqing, additional
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- 2021
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46. Insights into HONO sources from observations during a solar eclipse
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Singh, Ajit, primary, Crilley, Leigh R., additional, Pope, Francis D., additional, and Bloss, William J., additional
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- 2021
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47. Elevated levels of OH observed in haze events during wintertime in central Beijing
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Slater, Eloise J., primary, Whalley, Lisa K., additional, Woodward-Massey, Robert, additional, Ye, Chunxiang, additional, Lee, James D., additional, Squires, Freya, additional, Hopkins, James R., additional, Dunmore, Rachel E., additional, Shaw, Marvin, additional, Hamilton, Jacqueline F., additional, Lewis, Alastair C., additional, Crilley, Leigh R., additional, Kramer, Louisa, additional, Bloss, William, additional, Vu, Tuan, additional, Sun, Yele, additional, Xu, Weiqi, additional, Yue, Siyao, additional, Ren, Lujie, additional, Acton, W. Joe F., additional, Hewitt, C. Nicholas, additional, Wang, Xinming, additional, Fu, Pingqing, additional, and Heard, Dwayne E., additional
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- 2020
- Full Text
- View/download PDF
48. A comparison of PM<sub>2.5</sub>-bound polycyclic aromatic hydrocarbons in summer Beijing (China) and Delhi (India)
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Elzein, Atallah, primary, Stewart, Gareth J., additional, Swift, Stefan J., additional, Nelson, Beth S., additional, Crilley, Leigh R., additional, Alam, Mohammed S., additional, Reyes-Villegas, Ernesto, additional, Gadi, Ranu, additional, Harrison, Roy M., additional, Hamilton, Jacqueline F., additional, and Lewis, Alastair C., additional
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- 2020
- Full Text
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49. A portable, robust, stable, and tunable calibration source for gas-phase nitrous acid (HONO)
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Lao, Melodie, primary, Crilley, Leigh R., additional, Salehpoor, Leyla, additional, Furlani, Teles C., additional, Bourgeois, Ilann, additional, Neuman, J. Andrew, additional, Rollins, Andrew W., additional, Veres, Patrick R., additional, Washenfelder, Rebecca A., additional, Womack, Caroline C., additional, Young, Cora J., additional, and VandenBoer, Trevor C., additional
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- 2020
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50. Radical chemistry at a UK coastal receptor site -- Part 1: observations of OH, HO2, RO2, and OH reactivity and comparison to MCM model predictions.
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Woodward-Massey, Robert, Sommariva, Roberto, Whalley, Lisa K., Cryer, Danny R., Ingham, Trevor, Bloss, William J., Cox, Sam, Lee, James D., Reed, Chris P., Crilley, Leigh R., Kramer, Louisa J., Bandy, Brian J., Forster, Grant L., Reeves, Claire E., Monks, Paul S., and Heard., Dwayne E.
- Abstract
OH, HO
2 , total and partially-speciated RO2 , and OH reactivity (k'OH) were measured during the July 2015 ICOZA (Integrated Chemistry of OZone in the Atmosphere) project that took place at a coastal site in North Norfolk, UK. Maximum measured daily OH, HO2 , and total RO2 radical concentrations were in the range 2.6-17 × 106, 0.75-4.2 × 108, and 2.3-8.0 × 108 molecule cm-3 , respectively. k'OH ranged from 1.7 to 17.6 s-1 with a median value of 4.7 s-1 . ICOZA data were split by wind direction to assess differences in the radical chemistry between air that had passed over the North Sea (NW-SE sectors) or major urban conurbations such as London (SW sector). A photostationary steady-state (PSS) calculation underpredicted daytime OH in NW-SE air by ~35%, whereas agreement (~15%) was found within instrumental uncertainty (~26% at 2σ) in SW air. A box model using MCMv3.3.1 chemistry was in better agreement with the OH measurements, but it overpredicted HO2 observations in NW-SE air in the afternoon by a factor of ~2-3, although slightly bet ter agreement was found for HO2 in SW air (factor of ~1.4-2.0 underprediction). The box model severely underpredicted total RO2 observations in both NW-SE and SW air by factors of ~8-9 on average. Measured radical and k'OH levels and measurement-to-model ratios displayed strong dependences on NO mixing ratios. The PSS calculation could capture OH observations at high NO but underpredicted the observations at low NO. The box model overpredicted HO2 concentrations at low NO in NW-SE air, whereas in SW air, the measurements and model results were in agreement across the full NO range. The box model underpredicted total RO2 at all NO levels, where the measurement-to-model ratio scaled with NO. This trend has been found in all previous field campaigns in which total RO2 was measured using the ROx LIF technique and suggests that peroxy radical chemistry is not well understood under high NOx conditions. [ABSTRACT FROM AUTHOR]- Published
- 2022
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