Pollutant dispersion by tall buildings: laboratory experiments and Large-Eddy Simulation.

Abstract: Pollutant dispersion by a tall-building cluster within a low-rise neighbourhood of Beijing is investigated using both full-scale Large-Eddy Simulation and water flume experiments at 1:2400 model-to-full scale with Particle Image Velocimetry and Planar Laser-Induced Fluorescence. The Large-Eddy Simulation and flume results of this realistic test case agree remarkably well despite differences in the inflow conditions and scale. Tall buildings have strong influence on the local flow and the development of the rooftop shear layer which dominates vertical momentum and scalar fluxes. Additional measurements using tall-buildings-only models at both 1:2400 and 1:4800 scales indicates the rooftop shear layer is insensitive to the scale. The relatively thicker incoming boundary layer affects the Reynolds stresses, the relative size of the pollutant source affects the concentration statistics and the relative laser-sheet thickness affects the spatially averaged results of the measured flow field. Low-rise buildings around the tall building cluster cause minor but non-negligible offsets in the peak magnitude and vertical location, and have a similar influence on the velocity and concentration statistics as the scale choice. These observations are generally applicable to pollutant dispersion of realistic tall building clusters in cities. The consistency between simulations and water tunnel experiments indicates the suitability of both methodologies.

Nutritional intakes of highly trained adolescent swimmers before, during, and after a national lockdown in the COVID-19 pandemic.

Strict lockdown measures were introduced in response to the COVID-19 pandemic, which caused mass disruption to adolescent swimmers' daily routines. To measure how lockdown impacted nutritional practices in this cohort, three-day photograph food diaries were analysed at three time points: before (January), during (April), and after (September) the first UK lockdown. Thirteen swimmers (aged 15 ± 1 years) from a high-performance swimming club submitted satisfactory food diaries at all time points. During lockdown, lower amounts of energy (45.3 ± 9.8 vs. 31.1 ± 7.7 kcal∙kg BM∙day-1, p<0.001), carbohydrate (5.4 ± 1.2 vs. 3.5 ± 1.1 g∙kg BM∙day-1, p<0.001), protein (2.3 ± 0.4 vs. 1.7 ± 0.4 g∙kg BM∙day-1, p = 0.002), and fat (1.6 ± 0.4 vs. 1.1 ± 0.3 g∙kg BM∙day-1, p = 0.011) were reported. After lockdown, no nutritional differences were found in comparison compared to before lockdown (energy: 44.0 ± 12.1 kcal∙kg BM∙day-1; carbohydrate: 5.4 ± 1.4 g∙kg BM∙day-1; protein: 2.1 ± 0.6 g∙kg BM∙day-1; fat: 1.5 ± 0.6 g ∙kg BM∙day-1, all p>0.05), despite fewer training hours being completed (15.0 ± 1.4 vs. 19.1 ± 2.2 h∙week-1, p<0.001). These findings highlight the ability of adolescent swimmers to alter their nutrition based on their changing training circumstances when receiving sport nutrition support. However, some individuals displayed signs of suboptimal nutrition during lockdown that were not corrected once training resumed. This warrants future research to develop interactive education workshops that maintain focus and motivation towards optimal nutrition practices in isolated periods away from training.

Variability of physical meteorology in urban areas at different scales: implications for air quality.

Air quality in cities is influenced not only by emissions and chemical transformations but also by the physical state of the atmosphere which varies both temporally and spatially. Increasingly, tall buildings (TB) are common features of the urban landscape, yet their impact on urban air flow and dispersion is not well understood, and their effects are not appropriately captured in parameterisation schemes. Here, hardware models of areas within two global mega-cities (London and Beijing) are used to analyse the impact of TB on flow and transport in isolated and cluster settings. Results show that TB generate strong updrafts and downdrafts that affect street-level flow fields. Velocity differences do not decay monotonically with distance from the TB, especially in the near-wake region where the flow is characterised by recirculating winds and jets. Lateral distance from an isolated TB centreline is crucial, and flow is still strongly impacted at longitudinal distances of several TB heights. Evaluation of a wake-flow scheme (ADMS-Build) in the isolated TB case indicates important characteristics are not captured. There is better agreement for a slender, shorter TB than a taller non-cuboidal TB. Better prediction of flow occurs horizontally further away and vertically further from the surface. TB clusters modify the shape of pollutant plumes. Strong updrafts generated by the overlapping wakes of TB clusters lift pollutants out of the canopy, causing a much deeper tracer plume in the lee of the cluster, and an elevated plume centreline with maximum concentrations around the TB mean height. Enhanced vertical spread of the pollutants in the near-wake of the cluster results in overall lower maximum concentrations, but higher concentrations above the mean TB height. These results have important implications for interpreting observations in areas with TB. Using real world ceilometer observations in two mega-cities (Beijing and Paris), we assess the diurnal seasonal variability of the urban boundary layer and evaluate a mixed layer height (MLH) empirical model with parameters derived from a third mega-city (London). The MLH model works well in central Beijing but less well in suburban Paris. The variability of the physical meteorology across different vertical scales discussed in this paper provides additional context for interpreting air quality observations.

Assessment of Overheating Risk in Gynaecology Scanning Rooms during Near-Heatwave Conditions: A Case Study of the Royal Berkshire Hospital in the UK.

Hospital buildings in the UK are at particular risk to rising summer temperatures associated with climate change. Balancing the thermal needs of patients, staff, and visitors is a challenging, complex endeavour. A case study of the ultrasound area of the Royal Berkshire Hospital's Maternity and Gynaecology building is presented, where temperatures were measured for 35 days in waiting areas, staff offices, and ultrasound scanning rooms, aiming to assess the overheating risk posed to occupants. Local external temperature measurements were used for comparison whereby determining the indoor-outdoor environmental connection. Results show that most rooms had already breached standard overheating thresholds within the study period. Anthropogenic and waste heat from equipment has a noticeable effect on indoor temperatures. Local air-conditioning helped reduce the peaks in temperature seen between 14:00 and 17:00 for similar scanning rooms but is in contradiction to the National Health Service's sustainability plans. Several low-level solutions such as improved signage, access to water, and the allocation of vulnerable patients to morning clinics are suggested. Barriers to solutions are also discussed and the requirement of sufficient maintenance plans for cooling equipment is empathised. These solutions are likely to be applicable to other hospital buildings experiencing similar conditions.

Allergic multimorbidity of asthma, rhinitis and eczema over 20 years in the German birth cohort MAS.

BACKGROUND: The occurrence of allergic multimorbidity (coexistence of asthma, allergic rhinitis and eczema) has not been evaluated longitudinally from early childhood up to adulthood in a population-based study sample. We aimed to determine the prevalence of allergic multimorbidity up to age 20 stratified by parental allergies and sex/gender using extensive prospective follow-up data from two decades of a birth cohort study. METHODS: In 1990, we recruited 1314 healthy newborns from 6 maternity wards across Germany for the population-based MAS birth cohort study. The sample was purposely risk-enriched by increasing the proportion of children at high allergy risk (i.e. at least 2 allergic family members among parents and siblings) from 19% in the source population to 38% in the final sample. The remaining 62% of all MAS children had a low or no allergy risk. Symptoms, medication and doctor's diagnoses of allergic diseases have been assessed using standardized questionnaires including validated ISAAC questions in 19 follow-up assessments up to age 20. Allergic multimorbidity at each time point was defined as the coexistence of at least 2 of the following diseases in one participant: asthma, allergic rhinitis and eczema. RESULTS: Response at age 20 was 72% (n = 942) of all recruited participants. At age 20, 18.5% (95% CI, 15.0-22.5%) of all participants with allergic parents had 2 or 3 concurrent allergies as compared to only 6.3% (95% CI, 4.3-9.0%) of those with non-allergic parents. At this age, allergic multimorbidity was similar in women and men (12.7% (95% CI, 9.7-16.2%) vs. 11.6% (95% CI, 8.9-14.8%)), whereas single allergic diseases were slightly more common in women than men (24.2% (95% CI, 20.2-28.5%) vs. 20.1% (95% CI, 16.6-24.0%)). Asthma occurred more frequently with coexisting allergic rhinitis and/or eczema than as a single entity from pre-puberty to adulthood. CONCLUSION: Having parents with allergies is not only a strong predictor to develop any allergy, but it strongly increases the risk of developing allergic multimorbidity. In males and females alike, coexisting allergies were increasingly common throughout adolescence up to adulthood. Particularly asthma occurred in both sexes more frequently with coexisting allergies than as a single entity.

Prediction and prevention of allergic rhinitis: A birth cohort study of 20 years.

BACKGROUND: Allergic rhinitis (AR) is one of the most common chronic diseases, usually starting in the first 2 decades of life. Information on predictors, risk, and protective factors is missing because of a lack of long-term prospective studies. OBJECTIVE: Our aim was to examine early-life environmental and lifestyle determinants for AR up to age 20 years. METHODS: In 1990, the Multicenter Allergy Study included 1314 newborns in 5 German cities. Children were evaluated at 19 time points. A Cox regression model examined the associations between 41 independent early-life factors and onset of AR (as the primary outcome), including sensitization against aeroallergens and the secondary outcomes of nonallergic rhinitis and AR plus asthma. RESULTS: Two hundred ninety subjects had AR within 13,179 person years observed. The risk of AR was higher with a parental history of AR (adjusted hazard ratio [aHR], 2.49; 95% CI, 1.93-3.21), urticaria (aHR, 1.32; 95% CI, 1.00-1.74), or asthma (aHR, 1.29; 95% CI, 0.95-1.75). Early allergic sensitization (aHR, 4.53; 95% CI, 3.25-6.32), eczema within the first 3 years of life (aHR, 1.83; 95% CI, 1.38-2.42), male sex (aHR, 1.28; 95% CI, 1.02-1.61), and birthday in summer or autumn (aHR, 1.26; 95% CI, 1.00-1.58) were independent predictors of AR up to age 20 years. None of the other socioeconomic, environmental, lifestyle, pregnancy, and birth-related factors were associated with AR. CONCLUSION: Only nonmodifiable factors, particularly early allergic sensitization or eczema and parental AR, predicted AR up to age 20 years. No modifiable aspects of early-life environment or lifestyle were identified as targets for primary prevention.

Early-life determinants of asthma from birth to age 20 years: a German birth cohort study.

BACKGROUND: The lack of longitudinal data analyses from birth to adulthood is hampering long-term asthma prevention strategies. OBJECTIVE: We aimed to determine early-life predictors of asthma incidence up to age 20 years in a birth cohort study by applying time-to-event analysis. METHODS: In 1990, the Multicenter Allergy Study included 1314 newborns in 5 German cities. Children were evaluated from birth to age 20 years at 19 time points. Using a Cox regression model, we examined the associations between 36 early-life factors and onset of asthma based on a doctor's diagnosis or asthma medication (primary outcome), typical asthma symptoms, or allergic asthma (including positive IgE measurements). RESULTS: Response at 20 years was 71.6%. Two hundred eighteen subjects met the primary outcome criteria within 16,257 person years observed. Asthma incidence was lower in participants who were vaccinated (measles, mumps, and rubella vaccine/tick-borne encephalitis vaccine/BCG vaccine: adjusted hazard ratio [HR], 0.66 [95% CI, 0.47-0.93]). Up to age 20 years, asthma incidence was higher in subjects who had parents with allergic rhinitis (adjusted HR, 2.24 [95% CI, 1.67-3.02]), started day care early or late (before 18 months: adjusted HR, 1.79 [95% CI, 1.03-3.10]; after 3 years: adjusted HR, 1.64 [95% CI, 0.96-2.79]), had mothers who smoked during pregnancy (adjusted HR, 1.79 [95% CI, 1.20-2.67]), had poor parents (adjusted HR, 1.55 [95% CI, 1.09-2.22]), and had parents with asthma (adjusted HR, 1.65 [95% CI, 1.17-2.31]). Not associated with asthma were aspects of diet and breast-feeding, pet ownership, presence of older siblings, and passive smoking. CONCLUSION: Parental asthma and nasal allergy increase asthma incidence in offspring up to adulthood. Avoiding tobacco smoke exposure during pregnancy, receiving vaccinations in early childhood, and starting day care between 1.5 and 3 years of age might prevent or delay the development of asthma.

Implementation of anaphylaxis management guidelines: a register-based study.

BACKGROUND: Anaphylaxis management guidelines recommend the use of intramuscular adrenaline in severe reactions, complemented by antihistamines and corticoids; secondary prevention includes allergen avoidance and provision of self-applicable first aid drugs. Gaps between recommendations and their implementation have been reported, but only in confined settings. Hence, we analysed nation-wide data on the management of anaphylaxis, evaluating the implementation of guidelines. METHODS: Within the anaphylaxis registry, allergy referral centres across Germany, Austria and Switzerland provided data on severe anaphylaxis cases. Based on patient records, details on reaction circumstances, diagnostic workup and treatment were collected via online questionnaire. Report of anaphylaxis through emergency physicians allowed for validation of registry data. RESULTS: 2114 severe anaphylaxis patients from 58 centres were included. 8% received adrenaline intravenously, 4% intramuscularly; 50% antihistamines, and 51% corticoids. Validation data indicated moderate underreporting of first aid drugs in the Registry. 20% received specific instructions at the time of the reaction; 81% were provided with prophylactic first aid drugs at any time. CONCLUSION: There is a distinct discrepancy between current anaphylaxis management guidelines and their implementation. To improve patient care, a revised approach for medical education and training on the management of severe anaphylaxis is warranted.

The SWITCH study (sensing with insulin pump therapy to control HbA(1c)): design and methods of a randomized controlled crossover trial on sensor-augmented insulin pump efficacy in type 1 diabetes suboptimally controlled with pump therapy.

BACKGROUND: studies investigating the effect of real-time continuous glucose monitoring (CGM) combined with pump therapy on glycemic outcomes in type 1 diabetes are increasing. Pump therapy is well established as a "gold standard" for insulin delivery, offering improvements over multiple daily insulin injections. However, there is still a proportion of subjects using continuous subcutaneous insulin infusion in whom goals for metabolic control are far from achieved or benefits of this type of insulin therapy are transient. The SWITCH (Sensing With Insulin pump Therapy to Control HbA(1c) [hemoglobin A1c]) study is a multicenter, randomized, controlled, crossover study to evaluate if adding CGM to experienced pump patients with suboptimal metabolic control will provide additional insight enabling clinical and therapeutic benefit. METHODS: subjects meeting the inclusion criteria were randomized to Sensor On or Sensor Off arms for 6 months, after a 1-month run-in period. Following a 4-month washout period, the subjects crossed over to the other study arm for 6 months. The primary end point was the between arm difference in HbA(1c) levels. Among others, additional end points include time spent in different glycemic ranges, percentage of patients with HbA(1c) <7%, number of hypoglycemic events, glucose variability parameters, safety outcomes, treatment satisfaction, and quality of life. RESULTS: recruitment occurred between January 2008 and February 2009. A total of 153 patients were randomized. Study completion is anticipated in July 2010. CONCLUSIONS: the results will establish if adding CGM to existing, capable, insulin pump users can enable better metabolic control.