Is CO2 a good proxy for Indoor Air Quality in school classrooms?

Background The increasing interest in Indoor Air Quality (IAQ) of educational buildings has been underpinned by the rising incidence of asthma and respiratory disease among children, who spend a substantial amount of their lives on the school premises. The susceptibility of children compared with adults has led to the formulation of guidelines regulating IAQ in school buildings. WHO guidelines provide the scienti c basis for legally enforceable standards for non-industrial environments. Re ecting the relative di culty and expense of obtaining measurements of speci c pollutants, guidelines for the provision of adequate IAQ in UK schools have been typically framed around thermal conditions, carbon dioxide (CO2) levels, and estimated ventilation rates as a primary indicator of IAQ. Aim Drawing on detailed monitoring data from 15 primary and three nursery London classrooms, this thesis sets to evaluate if indoor CO2 levels in classrooms are a good indicator in ensuring a healthy and satisfactory school environment. To fully answer this question this thesis aims to associate levels of speci c indoor pollutants with CO2 levels and ventilation rates after controlling for environmental and behavioural factors; to identify speci c exposures in the classroom that may a ect asthma prevalence, selfreported health symptoms and perceived IAQ. Method The study was organised as a case-crossover study of the heating and non-heating season, and employed a multi-disciplinary methodology, including direct-reading instrumental sampling, passive sampling for long-term measurements, and determination of microbiological contaminants with molecular methods. The monitored data were matched with school and classroom characteristics, self-reported health symptoms and IAQ perception of 376 primary school students attending 15 classrooms with standardised questionnaires. The integrated database was analysed with Bayesian multilevel models that provide a concordance between theoretical approaches and statistical analysis, while taking into account the hierarchy of the data. Results Indoor CO2 levels and estimated ventilation rates were a reliable predictor for some outcomes, such as indoor temperature, Particulate Matter (PM) and Volatile Organic Compounds (VOCs) levels. Overall evidence from this study suggests that limiting CO2 levels below 1000 ppm (which is lower than current guideline values of BB101 performance standard in England (DfE, 2014)) is necessary in order to achieve indoor PM levels in classrooms below WHO 2010 annual guideline values, after removing indoor furnishing acting as dust reservoirs. A strong relationship between indoor temperatures and Total VOCs (TVOCs) levels emerged, and the predictive models estimated that after removing indoor TVOCs sources, keeping indoor temperatures below 26 C, and preferably below 22 C depending on season, may keep indoor TVOCs levels below 250ppb. Based on the self-reported satisfaction with IAQ at baseline and follow-up period, it was found that keeping indoor temperatures below 26 C and CO2 levels below 1000ppm, may additionally reduce predicted percentage of dissatisfaction with IAQ below 30%. The air was perceived as less acceptable with increasing indoor temperature and CO2 levels, stressing the importance for an integrated approach for the simultaneous provision of thermal comfort and IAQ. However, indoor CO2 levels were a poor predictor of tra c related pollutants, such as indoor NO2 levels, which were signi cantly associated with the high asthma prevalence reported in this study (OR: 1.11, 95% CI: 1.04-1.19). Exposure to tra c-related pollution levels was additionally associated with increased IAQ dissatisfaction, and higher prevalence and incidence of Sick Building Syndrome SBS symptoms. SBS describes a constellation of nonspeci c health symptoms including mucosal, dermal, respiratory and general, that have no clear aetiology and are attributable to exposure to a particular building environment. Recommendations for future research The methodological framework used in this study could be potentially applied to large scale investigations enhancing our understanding of the factors a ecting indoor pollution levels in educational settings. More research is necessary to validate the predictive model of satisfaction with IAQ in di erent climatic and geographical areas. Implications for policy This study shows that complaints about poor air quality and health symptoms were related to de ciencies in the indoor school environment, and identi ed that management and operation of classrooms are key in creating healthy and comfortable school buildings. Greening programmes around school buildings, simple passive measures of the building envelope, altering ventilation strategies among seasons, and timely control of ventilation may improve perceived IAQ and alleviate SBS symptoms. Together with increasing average and background ventilation rates, elimination of indoor sources that impact IAQ is necessar

Long-term, continuous air quality monitoring in a cross-sectional study of three UK non-domestic buildings

Long-term, continuous air quality monitoring has been carried out alongside seasonal passive sampling within a case study a hospital, school and office building, representing a cross-section of the UK non-domestic sector. This approach aimed at adopting state of the art sensor technology to provide a greater understanding of the variations in indoor air quality over time and how these variations relate to both building operation and occupant behavior. The results highlight how the relationship between indoor and outdoor air evolves considerably on both short and long-term basis, with varying behaviors then seen across different sources of pollutants. The mechanically ventilated hospital and school buildings demonstrate the effectiveness of particulate filters, with very low internal concentrations of PM2.5. However, high ventilation rates, combined with the absence of any filtration of NO2, resulted in the hospital having the highest indoor concentrations of NO2 and the highest associated indoor-outdoor ratio. Morning and evening traffic related peaks in NO2 can be observed indoors, with their penetration dependent upon the delivered ventilation rates. This demonstrates the impact of adopting high ventilation rates during peak traffic, and the consequences of CO2 based demand-controlled ventilation systems in polluted urban areas without full filtration. The naturally ventilated office then demonstrates significant seasonal variations, with increased ventilation openings resulting in indoor NO2 concentrations in the summer exceeding those in the winter, despite significant reductions in ambient levels. Conversely, concentrations of indoor pollutants are seen to reduce with increasing ventilation rates, demonstrating the complex balance between the dilution of indoor pollutants and penetration of outdoor sources. Despite significant reductions from the winter to the summer (21.6–11.2 μg/m3), all formaldehyde measurements in the naturally ventilated office exceeded guideline values, indicating improved guidance and product labelling schemes may be required to achieve these guideline concentrations and reduce associated health risks

Indoor school environments, physical activity, sitting behaviour and pedagogy: a scoping review

Physical activity levels in children are low and sitting time high, despite the health benefits of regular physical activity and limited sitting. Children spend a large proportion of their time at school, hence school-based interventions targeting physical activity and sitting behaviour may be important. Whilst some aspects of school buildings, their layout and furniture may influence children's physical activity and sitting, these effects could be intertwined with pedagogical approaches. This scoping review aims to identify gaps in the research literature regarding the influence of the indoor school environment on pedagogical approaches and on physical activity and sitting. In primary schools, it was found that physical activity can be integrated into lessons with some benefits on academic behaviour and possibly academic performance. Overall, however, the role of the indoor built environment is poorly investigated, although a handful of studies suggest that a radical change in primary school classrooms may increase physical activity and that stand-biased desks may be promising. This study provides a contribution to the emerging research fields of ‘active design’ from the perspective of indoor school design, highlighting a dearth of research, especially on sitting and for secondary education, and a lack of relevant conceptual frameworks

Introduction to Special Issue - In-depth study of air pollution sources and processes within Beijing and its surrounding region (APHH-2 Beijing)

Abstract. The Atmospheric Pollution and Human Health in a Chinese Megacity (APHH-Beijing) programme is an international collaborative project focusing on understanding the sources, processes and health effects of air pollution in the Beijing megacity. APHH-Beijing brings together leading China and UK research groups, state-of-the-art infrastructure and air quality models to work on four research themes: (1) sources and emissions of air pollutants; (2) atmospheric processes affecting urban air pollution; (3) air pollution exposure and health impacts; and (4) interventions and solutions. Themes 1 and 2 are closely integrated and support Theme 3, while Themes 1-3 provide scientific data for Theme 4 to develop cost-effective air pollution mitigation solutions. This paper provides an introduction to (i) the rationale of the APHH-Beijing programme, and (ii) the measurement and modelling activities performed as part of it. In addition, this paper introduces the meteorology and air quality conditions during two joint intensive field campaigns - a core integration activity in APHH-Beijing. The coordinated campaigns provided observations of the atmospheric chemistry and physics at two sites: (i) the Institute of Atmospheric Physics in central Beijing, and (ii) Pinggu in rural Beijing during 10 November – 10 December 2016 (winter) and 21 May- 22 June 2017 (summer). The campaigns were complemented by numerical modelling and automatic air quality and low-cost sensor observations in the Beijing megacity. In summary, the paper provides background information on the APHH-Beijing programme, and sets the scene for more focussed papers addressing specific aspects, processes and effects of air pollution in Beijing

Whey protein lowers blood pressure and improves endothelial function and lipid biomarkers in adults with prehypertension and mild hypertension: results from the chronic Whey2Go randomized 1,2 controlled trial

Background: Cardiovascular diseases (CVDs) are the greatest cause of death globally, and their reduction is a key public-health target. High blood pressure (BP) affects 1 in 3 people in the United Kingdom, and previous studies have shown that milk consumption is associated with lower BP. Objective: We investigated whether intact milk proteins lower 24-h ambulatory blood pressure (AMBP) and other risk markers of CVD. Design: The trial was a double-blinded, randomized, 3-way–crossover, controlled intervention study. Forty-two participants were randomly assigned to consume 2 × 28 g whey protein/d, 2 × 28 g Ca caseinate/d, or 2 × 27 g maltodextrin (control)/d for 8 wk separated by a 4-wk washout. The effects of these interventions were examined with the use of a linear mixed-model ANOVA. Results: Thirty-eight participants completed the study. Significant reductions in 24-h BP [for systolic blood pressure (SBP): −3.9 mm Hg; for diastolic blood pressure (DBP): −2.5 mm Hg; P = 0.050 for both)] were observed after whey-protein consumption compared with control intake. After whey-protein supplementation compared with control intake, peripheral and central systolic pressures [−5.7 mm Hg (P = 0.007) and −5.4 mm Hg (P = 0.012), respectively] and mean pressures [−3.7 mm Hg (P = 0.025) and −4.0 mm Hg (P = 0.019), respectively] were also lowered. Flow-mediated dilation (FMD) increased significantly after both whey-protein and calcium-caseinate intakes compared with control intake [1.31% (P < 0.001) and 0.83% (P = 0.003), respectively]. Although both whey protein and calcium caseinate significantly lowered total cholesterol [−0.26 mmol/L (P = 0.013) and −0.20 mmol/L (P = 0.042), respectively], only whey protein decreased triacylglycerol (−0.23 mmol/L; P = 0.025) compared with the effect of the control. Soluble intercellular adhesion molecule 1 and soluble vascular cell adhesion molecule 1 were reduced after whey protein consumption (P = 0.011) and after calcium-caseinate consumption (P = 0.039), respectively, compared with after control intake. Conclusions: The consumption of unhydrolyzed milk proteins (56 g/d) for 8 wk improved vascular reactivity, biomarkers of endothelial function, and lipid risk factors. Whey-protein supplementation also lowered 24-h ambulatory SBP and DBP. These results may have important implications for public health. This trial was registered at clinicaltrials.gov as NCT02090842

Personal exposure to air pollution and respiratory health of COPD patients in London

Previous studies have investigated the effects of air pollution on chronic obstructive pulmonary disease (COPD) patients using either fixed site measurements or a limited number of personal measurements, usually for one pollutant and a short time period. These limitations may introduce bias and distort the epidemiological associations as they do not account for all the potential sources or the temporal variability of pollution.We used detailed information on individuals' exposure to various pollutants measured at fine spatio-temporal scale to obtain more reliable effect estimates. A panel of 115 patients was followed up for an average continuous period of 128 days carrying a personal monitor specifically designed for this project that measured temperature, PM10, PM2.5, NO2, NO, CO and O3 at one-minute time resolution. Each patient recorded daily information on respiratory symptoms and measured peak expiratory flow (PEF). A pulmonologist combined related data to define a binary variable denoting an "exacerbation". The exposure-response associations were assessed with mixed-effects models.We found that gaseous pollutants were associated with a deterioration in patients' health. We observed an increase of 16.4% (95% confidence interval: 8.6-24.6%), 9.4% (5.4-13.6%) and 7.6% (3.0-12.4%) in the odds of exacerbation for an interquartile range increase in NO2, NO and CO respectively. Similar results were obtained for cough and sputum. O3 was found to have adverse associations with PEF and breathlessness. No association was observed between particles and any outcome.Our findings suggest that, when considering total personal exposure to air pollutants, mainly the gaseous pollutants affect COPD patients' health

Global associations between air pollutants and Chronic Obstructive Pulmonary Disease (COPD) exacerbations: a systematic review

Background: COPD exacerbations (AECOPD) affect lung function decline and quality of life. The effect of exposure to different air pollutants on AECOPD is unclear. Aim: We systematically reviewed the literature examining associations between air pollutants and hospital admissions for AECOPD. Methods: MEDLINE, EMBASE, BIOSIS & Science Citation Index were searched until September 2015. Inclusion criteria focused on studies presenting solely a COPD outcome defined by hospital admissions, and a measure of gaseous air pollutants and particle fractions. The association between each pollutant with COPD admissions was investigated in meta-analyses using random-effects models. Analyses were stratified by geographical clusters to investigate the evidence worldwide. Results: 46 studies were included and results showed marginal positive associations. The number of included studies was small with high heterogeneity between them and there was evidence of small-study bias. Geographical clustering of the effects of pollution on COPD hospital admissions was evident and reduced heterogeneity significantly. The most consistent association was between a 1mg/m3 increase in carbon monoxide levels with COPD related admissions; Odds Ratio: 1.2 (95%CI: 1.01-1.03). Conclusions: There is mixed evidence on the effects of pollution on AECOPD. Limitations of previous studies include the low spatio-temporal resolution of pollutants, inadequate control for confounding factors, and the use of aggregated health data that ignore personal characteristics. The need for personal exposure monitoring in a large number of geographical locations is evident

The economic benefits of reducing the levels of nitrogen dioxide (NO2) near primary schools: The case of London.

Providing a healthy school environment is a priority for child health. The aim of this study is to develop a methodology that allows quantification of the potential economic benefit of reducing indoor exposure to nitrogen dioxide (NO2) in children attending primary schools. Using environmental and health data collected in primary schools in London, this study estimates that, on average, 82 asthma exacerbations per school can be averted each year by reducing outdoor NO2 concentrations. The study expands upon previous analyses in two ways: first it assesses the health benefits of reducing children's exposure to indoor NO2 while at school, second it considers the children's perspective in the economic evaluation. Using a willingness to pay approach, the study quantifies that the monetary benefits of reducing children's indoor NO2 exposure while at school would range between £2.5 k per school if a child's perspective based on child's budget is adopted up to £60 k if a parent's perspective is considered. This study highlights that designers, engineers, policymakers and stakeholders need to consider the reduction of outdoor pollution, and particularly NO2 levels, near primary schools as there may be substantial health and monetary benefits

Seasonal variations and the influence of ventilation rates on IAQ: A case study of five low-energy London apartments

The indoor air quality (IAQ) of five low-energy London apartments has been assessed through the measurement of 16 key pollutants, using continuous and diffusive methods across heating and non-heating seasons. This case study approach aimed to assess the presence of pollutants within low-energy apartments and to better understand the role of ventilation and seasonal variations in indoor air quality. The results indicate strong seasonal variations, driven by increased natural ventilation rates over the summer monitoring period. A combined metric for indoor and outdoor pollutants ( Itot) suggests that the IAQ in the winter ( Itot = 17.7) is more than twice as bad as that seen in the summer ( Itot = 8.6). Formaldehyde concentrations were lower in the non-heating season, indicating increased ventilation rates more than offset increased off-gassing, in contrast to findings in other studies. However, increased summertime ventilation rates were observed to increase the proportion of outdoor pollutants entering the internal environment. This resulted in higher indoor concentrations of NO2 in the summer than the winter, despite significant reductions in outdoor concentrations. These results demonstrate the impact of ventilation practices upon IAQ, the influence of occupant actions and the complex relationship ventilation rates play in balancing indoor and outdoor sources of air pollution. </jats:p

Recruitment of patients with Chronic Obstructive Pulmonary Disease (COPD) from the Clinical Practice Research Datalink (CPRD) for research.

Databases of electronic health records (EHR) are not only a valuable source of data for health research but have also recently been used as a medium through which potential study participants can be screened, located and approached to take part in research. The aim was to assess whether it is feasible and practical to screen, locate and approach patients to take part in research through the Clinical Practice Research Datalink (CPRD). This is a cohort study in primary care. The CPRD anonymised EHR database was searched to screen patients with Chronic Obstructive Pulmonary Disease (COPD) to take part in a research study. The potential participants were contacted via their General Practitioner (GP) who confirmed their eligibility. Eighty two practices across Greater London were invited to the study. Twenty-six (31.7%) practices consented to participate resulting in a pre-screened list of 988 patients. Of these, 632 (63.7%) were confirmed as eligible following the GP review. Two hundred twenty seven (36%) response forms were received by the study team; 79 (34.8%) responded 'yes' (i.e., they wanted to be contacted by the research assistant for more information and to talk about enrolling in the study), and 148 (65.2%) declined participation. This study has shown that it is possible to use EHR databases such as CPRD to screen, locate and recruit participants for research. This method provides access to a cohort of patients while minimising input needed by GPs and allows researchers to examine healthcare usage and disease burden in more detail and in real-life settings