Rapid economic growth and development have exacerbated air quality problems across India, driven by many poorly understood pollution sources and understanding their relative importance remains ...critical to characterising the key drivers of air pollution. A comprehensive suite of measurements of 90 non-methane hydrocarbons (NMHCs) (C
2
-C
14
), including 12 speciated monoterpenes and higher molecular weight monoaromatics, were made at an urban site in Old Delhi during the pre-monsoon (28-May to 05-Jun 2018) and post-monsoon (11 to 27-Oct 2018) seasons using dual-channel gas chromatography (DC-GC-FID) and two-dimensional gas chromatography (GC×GC-FID). Significantly higher mixing ratios of NMHCs were measured during the post-monsoon campaign, with a mean night-time enhancement of around 6. Like with NO
x
and CO, strong diurnal profiles were observed for all NMHCs, except isoprene, with very high NMHC mixing ratios between 35-1485 ppbv. The sum of mixing ratios of benzene, toluene, ethylbenzene and xylenes (BTEX) routinely exceeded 100 ppbv at night during the post-monsoon period, with a maximum measured mixing ratio of monoaromatic species of 370 ppbv. The mixing ratio of highly reactive monoterpenes peaked at around 6 ppbv in the post-monsoon campaign and correlated strongly with anthropogenic NMHCs, suggesting a strong non-biogenic source in Delhi. A detailed source apportionment study was conducted which included regression analysis to CO, acetylene and other NMHCs, hierarchical cluster analysis, EPA UNMIX 6.0, principal component analysis/absolute principal component scores (PCA/APCS) and comparison with NMHC ratios (benzene/toluene and
i
-/
n
-pentane) in ambient samples to liquid and solid fuels. These analyses suggested the primary source of anthropogenic NMHCs in Delhi was from traffic emissions (petrol and diesel), with average mixing ratio contributions from Unmix and PCA/APCS models of 38% from petrol, 14% from diesel and 32% from liquified petroleum gas (LPG) with a smaller contribution (16%) from solid fuel combustion. Detailed consideration of the underlying meteorology during the campaigns showed that the extreme night-time mixing ratios of NMHCs during the post-monsoon campaign were the result of emissions into a very shallow and stagnant boundary layer. The results of this study suggest that despite widespread open burning in India, traffic-related petrol and diesel emissions remain the key drivers of gas-phase urban air pollution in Delhi.
Characterisation of the sources of non-methane volatile organic compounds in surface air in Delhi, India.
The National Bariatric Surgery Registry (NBSR) is the largest bespoke database in the field in the United Kingdom.
Our aim was to analyze the NBSR to determine whether the effects of obesity surgery ...on associated co-morbidities observed in small randomized controlled clinical trials could be replicated in a "real life" setting within U.K. healthcare.
United Kingdom.
All NBSR entries for operations between 2000 and 2015 with associated demographic and co-morbidity data were analyzed retrospectively.
A total of 50,782 entries were analyzed. The patients were predominantly female (78%) and white European with a mean age of 45 ± 11 years and a mean body mass index of 48 ± 8 kg/m2. Over 5 years of follow-up, statistically significant reductions in the prevalence of type 2 diabetes, hypertension, dyslipidemia, sleep apnea, asthma, functional impairment, arthritis, and gastroesophageal reflux disease were observed. The "remission" of these co-morbidities was evident 1 year postoperatively and reached a plateau 2 to 5 years after surgery. Obesity surgery was particularly effective on functional impairment and diabetes, almost doubling the proportion of patients able to climb 3 flights of stairs and halving the proportion of patients with diabetes related hyperglycemia compared with preoperatively. Surgery was safe with a morbidity of 3.1% and in-hospital mortality of .07% and a reduced median inpatient stay of 2 days, despite an increasingly sick patient population.
Obesity surgery in the U.K. results not only in weight loss, but also in substantial improvements in obesity-related co-morbidities. Appropriate support and funding will help improve the quality of the NBSR data set even further, thus enabling its use to inform healthcare policy.
The formation of isoprene nitrates (IsN) can lead to significant secondary organic aerosol (SOA) production and they can act as reservoirs of atmospheric nitrogen oxides. In this work, we estimate ...the rate of production of IsN from the reactions of isoprene with OH and NO3 radicals during the summertime in Beijing. While OH dominates the loss of isoprene during the day, NO3 plays an increasingly important role in the production of IsN from the early afternoon onwards. Unusually low NO concentrations during the afternoon resulted in NO3 mixing ratios of ca. 2 pptv at approximately 15:00, which we estimate to account for around a third of the total IsN production in the gas phase. Heterogeneous uptake of IsN produces nitrooxyorganosulfates (NOS). Two mono-nitrated NOS were correlated with particulate sulfate concentrations and appear to be formed from sequential NO3 and OH oxidation. Di- and tri-nitrated isoprene-related NOS, formed from multiple NO3 oxidation steps, peaked during the night. This work highlights that NO3 chemistry can play a key role in driving biogenic–anthropogenic interactive chemistry in Beijing with respect to the formation of IsN during both the day and night.
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IJS, KILJ, NUK, PNG, UL, UM
The impact of emissions of volatile organic compounds (VOCs) to the
atmosphere on the production of secondary pollutants, such as ozone and
secondary organic aerosol (SOA), is mediated by the ...concentration of nitric
oxide (NO). Polluted urban atmospheres are typically considered to be
“high-NO” environments, while remote regions such as rainforests, with
minimal anthropogenic influences, are considered to be “low NO”. However,
our observations from central Beijing show that this simplistic separation
of regimes is flawed. Despite being in one of the largest megacities in the
world, we observe formation of gas- and aerosol-phase oxidation products
usually associated with low-NO “rainforest-like” atmospheric oxidation
pathways during the afternoon, caused by extreme suppression of NO
concentrations at this time. Box model calculations suggest that during
the morning high-NO chemistry predominates (95 %) but in the afternoon
low-NO chemistry plays a greater role (30 %). Current emissions
inventories are applied in the GEOS-Chem model which shows that such models,
when run at the regional scale, fail to accurately predict such an extreme
diurnal cycle in the NO concentration. With increasing global emphasis on
reducing air pollution, it is crucial for the modelling tools used to
develop urban air quality policy to be able to accurately represent such
extreme diurnal variations in NO to accurately predict the formation of
pollutants such as SOA and ozone.
The first nitryl chloride (ClNO2) measurements in the UK were made during the summer 2012 ClearfLo campaign with a chemical ionization mass spectrometer, utilizing an I− ionization scheme. ...Concentrations of ClNO2 exceeded detectable limits (11 ppt) every night with a maximum concentration of 724 ppt. A diurnal profile of ClNO2 peaking between 4 and 5 A.M., decreasing directly after sunrise, was observed. Concentrations of ClNO2 above the detection limit are generally observed between 8 P.M. and 11 A.M. Different ratios of the production of ClNO2:N2O5 were observed throughout with both positive and negative correlations between the two species being reported. The photolysis of ClNO2 and a box model utilizing the Master Chemical Mechanism modified to include chlorine chemistry was used to calculate Cl atom concentrations. Simultaneous measurements of hydroxyl radicals (OH) using low pressure laser‐induced fluorescence and ozone enabled the relative importance of the oxidation of three groups of measured VOCs (alkanes, alkenes, and alkynes) by OH radicals, Cl atoms, and O3 to be compared. For the day with the maximum calculated Cl atom concentration, Cl atoms in the early morning were the dominant oxidant for alkanes and, over the entire day, contributed 15%, 3%, and 26% toward the oxidation of alkanes, alkenes, and alkynes, respectively.
Key Points
The first UK measurements of ClNO2 using CIMS
Relationships between N2O5 and ClNO2 were dependent on air mass origins
Cl oxidizes 14.5%, 2.6%, and 25% of alkanes, alkenes, and alkynes
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Over the last 2 decades, the importance of emissions source types of atmospheric pollutants in urban areas has undergone significant change. In particular, there has been a considerable reduction in ...emissions associated with road vehicles. Understanding the role played by different source sectors is important if effective air pollution control is to be achieved. Current atmospheric measurements are made at fixed monitoring sites, most of which do not include the measurement of volatile organic compounds (VOCs), so our understanding of the temporal and spatial variation of pollutants is limited. Here we describe the application of a mobile laboratory using a selected-ion flow-tube mass spectrometer (SIFT-MS) and other trace gas instrumentation to provide on-road, high-spatial- and temporal-resolution measurements of CO2, CH4, VOCs and other trace gases. We then illustrate the potential of this platform for developing source characterisation methods that account for the similarity in correlation between species. Finally, we consider the benefits of high-spatial- and temporal-resolution measurements in characterising different types of sources, which would be difficult or impossible for single-species studies.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Obesity levels in the UK have reached a sustained high and ∼4% of the population would be candidates for bariatric surgery based upon current UK NICE guidelines, which has important implications for ...Clinical Commissioning Groups.
Summary data from Cochrane systematic reviews, randomized controlled trials (RCTs) and cohort studies.
Currently, the only treatment that offers significant and durable weight loss for those with severe and complex obesity is surgery. Three operations account for 95% of all bariatric surgery in the UK, but the NHS offers surgery to only a small fraction of those who could benefit. Laparoscopic adjustable gastric banding (gastric banding) has potentially the lowest risk and up-front costs of the three procedures.
Reliable Level 1 evidence of the relative effectiveness of the operations is lacking.
As a point intervention, weight loss surgery together with the chronic disease management strategy for obesity can prevent significant future disease and mortality, and the NHS should embrace both.
Better RCT evidence is needed including clinical effectiveness and economic analysis to answer the important question 'which is the best of the three operations most frequently performed?' This review considers the current evidence for gastric banding for the treatment of severe and complex obesity.
Objectives We examined outcomes of patients resuscitated from cardiac arrest owing to ST-segment elevation myocardial infarction (STEMI) and predictors of survival and neurologic recovery. Background ...Immediately after resuscitation from cardiac arrest owing to STEMI, many patients show signs of neurologic impairment, and benefits of percutaneous coronary intervention and subsequent prognosis are not well defined. Methods Between January 1, 2002, and December 31, 2006, we retrospectively identified consecutive patients resuscitated from cardiac arrest, regardless of time to return of spontaneous circulation (ROSC) and neurologic status, and reviewed the outcomes of those who had STEMI. Mortality and neurologic recovery at discharge and long-term mortality were assessed by individual chart review for those who underwent emergent angiography. Results Our study population consisted of 98 patients; 64% survived to discharge, and 92% had a full neurologic recovery. Predictors of survival were shorter time to ROSC, younger age, neurologic status post-resuscitation (alert or minimally responsive), and male sex. Predictors of neurologic recovery included shorter time to ROSC, neurologic status post-resuscitation (alert or minimally responsive), and younger age. Ninety-six percent of patients who were alert post-resuscitation survived. Ninety-three percent of patients who were minimally responsive post-resuscitation survived. Fifty-nine patients were unresponsive post-resuscitation, with 44% survival, of whom 88% had full neurologic recovery. In the unresponsive group, unwitnessed arrest, prolonged ROSC, and older age were associated with increased risk of death, and older age and prolonged ROSC predicted poor neurologic recovery. Conclusions When resuscitated patients with STEMI are being evaluated in the emergency department, serious consideration should be given to emergent angiography and revascularization, regardless of neurologic status.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Isoprene is the most important biogenic volatile organic compound in the atmosphere. Its calculated impact on ozone (O.sub.3) is critically dependent on the model isoprene oxidation chemical scheme, ...in particular the way the isoprene-derived organic nitrates (IN) are treated. By combining gas chromatography with mass spectrometry, we have developed a system capable of separating and unambiguously measuring individual IN isomers. In this paper we use measurements from its first field deployment, which took place in Beijing as part of the Atmospheric Pollution and Human Health in a Chinese Megacity programme, to test understanding of the isoprene chemistry as simulated in the Master Chemical Mechanism (MCM) (v.3.3.1). Seven individual isoprene nitrates were identified and quantified during the campaign: two β-hydroxy nitrates (IHN), four delta-carbonyl nitrates (ICN), and propanone nitrate.
Organic aerosols, a major constituent of fine particulate mass in megacities, can be directly emitted or formed from secondary processing of biogenic and anthropogenic volatile organic compound ...emissions. The complexity of volatile organic compound emission sources, speciation and oxidation pathways leads to uncertainties in the key sources and chemistry leading to formation of organic aerosol in urban areas. Historically, online measurements of organic aerosol composition have been unable to resolve specific markers of volatile organic compound oxidation, while offline analysis of markers focus on a small proportion of organic aerosol and lack the time resolution to carry out detailed statistical analysis required to study the dynamic changes in aerosol sources and chemistry. Here we use data collected as part of the joint UK-China Air Pollution and Human Health (APHH-Beijing) collaboration during a field campaign in urban Beijing in the summer of 2017 alongside laboratory measurements of secondary organic aerosol from oxidation of key aromatic precursors (1,3,5-trimethyl benzene, 1,2,4-trimethyl benzene, propyl benzene, isopropyl benzene and 1-methyl naphthalene) to study the anthropogenic and biogenic contributions to organic aerosol. For the first time in Beijing, this study applies positive matrix factorisation to online measurements of organic aerosol composition from a time-of-flight iodide chemical ionisation mass spectrometer fitted with a filter inlet for gases and aerosols (FIGAERO-ToF-I-CIMS). This approach identifies the real-time variations in sources and oxidation processes influencing aerosol composition at a near-molecular level. We identify eight factors with distinct temporal variability, highlighting episodic differences in OA composition attributed to regional influences and
in situ
formation. These have average carbon numbers ranging from C
5
-C
9
and can be associated with oxidation of anthropogenic aromatic hydrocarbons alongside biogenic emissions of isoprene, α-pinene and sesquiterpenes.
We study the anthropogenic and biogenic contributions to organic aerosol.
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