The Effects of Global Change Upon United States Air Quality

To understand more fully the effects of global changes on ambient concentrations of ozone and particulate matter with aerodynamic diameter smaller than 2.5 μm (PM2.5) in the United States (US), we conducted a comprehensive modeling effort to evaluate explicitly the effects of changes in climate, biogenic emissions, land use and global/regional anthropogenic emissions on ozone and PM2.5 concentrations and composition. Results from the ECHAM5 global climate model driven with the A1B emission scenario from the Intergovernmental Panel on Climate Change (IPCC) were downscaled using the Weather Research and Forecasting (WRF) model to provide regional meteorological fields. We developed air quality simulations using the Community Multiscale Air Quality Model (CMAQ) chemical transport model for two nested domains with 220 and 36 km horizontal grid cell resolution for a semi-hemispheric domain and a continental United States (US) domain, respectively. The semi-hemispheric domain was used to evaluate the impact of projected global emissions changes on US air quality. WRF meteorological fields were used to calculate current (2000s) and future (2050s) biogenic emissions using the Model of Emissions of Gases and Aerosols from Nature (MEGAN). For the semi-hemispheric domain CMAQ simulations, present-day global emissions inventories were used and projected to the 2050s based on the IPCC A1B scenario. Regional anthropogenic emissions were obtained from the US Environmental Protection Agency National Emission Inventory 2002 (EPA NEI2002) and projected to the future using the MARKet ALlocation (MARKAL) energy system model assuming a business as usual scenario that extends current decade emission regulations through 2050. Our results suggest that daily maximum 8 h average ozone (DM8O) concentrations will increase in a range between 2 to 12 parts per billion (ppb) across most of the continental US. The highest increase occurs in the South, Central and Midwest regions of the US due to increases in temperature, enhanced biogenic emissions and changes in land use. The model predicts an average increase of 1–6 ppb in DM8O due to projected increase in global emissions of ozone precursors. The effects of these factors are only partially offset by reductions in DM8O associated with decreasing US anthropogenic emissions. Increases in PM2.5 levels between 4 and 10 μg m−3 in the Northeast, Southeast, Midwest and South regions are mostly a result of increase in primary anthropogenic particulate matter (PM), enhanced biogenic emissions and land use changes. Changes in boundary conditions shift the composition but do not alter overall simulated PM2.5 mass concentrations

The effects of global change upon United States air quality

To understand more fully the effects of global changes on ambient concentrations of ozone and particulate matter with aerodynamic diameter smaller than 2.5 μm (PM2.5) in the United States (US), we conducted a comprehensive modeling effort to evaluate explicitly the effects of changes in climate, biogenic emissions, land use and global/regional anthropogenic emissions on ozone and PM2.5 concentrations and composition. Results from the ECHAM5 global climate model driven with the A1B emission scenario from the Intergovernmental Panel on Climate Change (IPCC) were downscaled using the Weather Research and Forecasting (WRF) model to provide regional meteorological fields. We developed air quality simulations using the Community Multiscale Air Quality Model (CMAQ) chemical transport model for two nested domains with 220 and 36 km horizontal grid cell resolution for a semi-hemispheric domain and a continental United States (US) domain, respectively. The semi-hemispheric domain was used to evaluate the impact of projected global emissions changes on US air quality. WRF meteorological fields were used to calculate current (2000s) and future (2050s) biogenic emissions using the Model of Emissions of Gases and Aerosols from Nature (MEGAN). For the semi-hemispheric domain CMAQ simulations, present-day global emissions inventories were used and projected to the 2050s based on the IPCC A1B scenario. Regional anthropogenic emissions were obtained from the US Environmental Protection Agency National Emission Inventory 2002 (EPA NEI2002) and projected to the future using the MARKet ALlocation (MARKAL) energy system model assuming a business as usual scenario that extends current decade emission regulations through 2050. Our results suggest that daily maximum 8 h average ozone (DM8O) concentrations will increase in a range between 2 to 12 parts per billion (ppb) across most of the continental US. The highest increase occurs in the South, Central and Midwest regions of the US due to increases in temperature, enhanced biogenic emissions and changes in land use. The model predicts an average increase of 1–6 ppb in DM8O due to projected increase in global emissions of ozone precursors. The effects of these factors are only partially offset by reductions in DM8O associated with decreasing US anthropogenic emissions. Increases in PM2.5 levels between 4 and 10 μg m−3 in the Northeast, Southeast, Midwest and South regions are mostly a result of increase in primary anthropogenic particulate matter (PM), enhanced biogenic emissions and land use changes. Changes in boundary conditions shift the composition but do not alter overall simulated PM2.5 mass concentrations

The QuinteT Recruitment Intervention supported five randomized trials to recruit to target: a mixed-methods evaluation

ObjectiveTo evaluate the impact of the Quintet Recruitment Intervention (QRI) on recruitment in challenging randomized controlled trials (RCTs) that have applied the intervention. The QRI aims to understand recruitment difficulties, and then implements ‘QRI-actions’ to address these as recruitment proceeds.Study Design and SettingA mixed-methods study, comprising: a) before-and-after comparisons of recruitment rates and numbers of patients approached, and b) qualitative case studies, including documentary analysis and interviews with RCT investigators.ResultsFive UK-based publicly-funded RCTs were included in the evaluation. All recruited to target. RCT2 and RCT5 both received up-front pre-recruitment training before the intervention was applied. RCT2 did not encounter recruitment issues and recruited above target from its outset. Recruitment difficulties, particularly communication issues, were identified and addressed through QRI-actions in RCTs 1, 3, 4 and 5. Randomization rates significantly improved post-QRI-action in RCTs 1,3, and 4. QRI-actions addressed issues with approaching eligible patients in RCTs 3 and 5, which both saw significant increases in patients approached. Trial investigators reported that the QRI had unearthed issues they had been unaware of, and reportedly changed their practices post QRI-action.ConclusionThere is promising evidence to suggest the QRI can support recruitment to difficult RCTs. This needs to be substantiated with future controlled evaluations

Predicting blood transfusion in patients undergoing minimally invasive oesophagectomy

AbstractAim: To evaluate predictors of allogenic blood transfusion requirements in patients undergoing minimal invasive oesophagectomy at a tertiary high volume centre for oesophago-gastric surgery. Methods: Retrospective analysis of all patients undergoing minimal access oesophagectomy in our department between January 2010 and December 2011. Patients were divided into two groups depending on whether they required a blood transfusion at any time during their index admission. Factors that have been shown to influence perioperative blood transfusion requirements in major surgery were included in the analysis. Binary logistic regression analysis was performed to determine the impact of patient and perioperative characteristics on transfusion requirements during the index admission. Results: A total of 80 patients underwent minimal access oesophagectomy, of which 61 patients had a laparoscopic assisted oesophagectomy and 19 patients had a minimal invasive oesophagectomy. Perioperative blood transfusion was required in 28 patients at any time during hospital admission. On binary logistic regression analysis, a lower preoperative haemoglobin concentration (p < 0.01), suffering a significant complication (p < 0.005) and laparoscopic assisted oesophagectomy (p < 0.05) were independent predictors of blood transfusion requirements. Discussion: It has been reported that requirement for blood transfusion can affect long-term outcomes in oesophageal cancer resection. Two factors which could be addressed preoperatively; haemoglobin concentration and type of oesophageal resection, may be valuable in predicting blood transfusions in patients undergoing minimally invasive oesophagectomy. Conclusion: Our analysis revealed that preoperative haemoglobin concentration, occurrence of significant complications and type of minimal access oesophagectomy predicted blood transfusion requirements in the patient population examined

Global Source–Receptor Relationships for Mercury Deposition Under Present-Day and 2050 Emissions Scenarios

Global policies regulating anthropogenic mercury require an understanding of the relationship between emitted and deposited mercury on intercontinental scales. Here, we examine source–receptor relationships for present-day conditions and four 2050 IPCC scenarios encompassing a range of economic development and environmental regulation projections. We use the GEOS-Chem global model to track mercury from its point of emission through rapid cycling in surface ocean and land reservoirs to its accumulation in longer lived ocean and soil pools. Deposited mercury has a local component (emitted HgII, lifetime of 3.7 days against deposition) and a global component (emitted Hg0, lifetime of 6 months against deposition). Fast recycling of deposited mercury through photoreduction of HgII and re-emission of Hg0 from surface reservoirs (ice, land, surface ocean) increases the effective lifetime of anthropogenic mercury to 9 months against loss to legacy reservoirs (soil pools and the subsurface ocean). This lifetime is still sufficiently short that source–receptor relationships have a strong hemispheric signature. Asian emissions are the largest source of anthropogenic deposition to all ocean basins, though there is also regional source influence from upwind continents. Current anthropogenic emissions account for only about one-third of mercury deposition to the global ocean with the remainder from natural and legacy sources. However, controls on anthropogenic emissions would have the added benefit of reducing the legacy mercury re-emitted to the atmosphere. Better understanding is needed of the time scales for transfer of mercury from active pools to stable geochemical reservoirs.Engineering and Applied Science

An intercomparison and evaluation of aircraft-derived and simulated CO from seven chemical transport models during the TRACE-P experiment

Four global scale and three regional scale chemical transport models are intercompared and evaluated during NASA's Transport and Chemical Evolution over the Pacific (TRACE-P) experiment. Model simulated and measured CO are statistically analyzed along aircraft flight tracks. Results for the combination of 11 flights show an overall negative bias in simulated CO. Biases are most pronounced during large CO events. Statistical agreements vary greatly among the individual flights. Those flights with the greatest range of CO values tend to be the worst simulated. However, for each given flight, the models generally provide similar relative results. The models exhibit difficulties simulating intense CO plumes. CO error is found to be greatest in the lower troposphere. Convective mass flux is shown to be very important, particularly near emissions source regions. Occasionally meteorological lift associated with excessive model-calculated mass fluxes leads to an overestimation of middle and upper tropospheric mixing ratios. Planetary Boundary Layer (PBL) depth is found to play an important role in simulating intense CO plumes. PBL depth is shown to cap plumes, confining heavy pollution to the very lowest levels