The clustering of health-related behaviours in a British population sample: testing for cohort differences

Research findings indicate that health-related behaviours (HRBs) do not co-occur within individuals by chance and therefore cluster. This study uses Latent Profile Analysis (LPA), to identify the clustered patterns and prevalence of four HRBs: smoking, alcohol, diet, physical activity. We used data, collected from participants in their early 30s, from two British cohorts born in 1958 and 1970 (N=21,019). Multi-group LPA models were run separately by gender testing for cohort differences in HRB cluster patterns. For both genders three clusters emerged: 'Risky' (1-9%), 'Moderate Smokers' (20-30%) and 'Mainstream' (68-77%). HRBs amongst members of the 'Mainstream' cluster were more beneficial than HRBs amongst members of the other two clusters, characterised as not smoking, frequent fruit and vegetable consumption, less frequent consumption of chips and fried food and being more physically active. Nevertheless, frequent consumption of sweet foods was common in the 'Mainstream' cluster. There was a large shift in membership to the 'Mainstream' cluster for men and women born in 1970. Amongst women members of the 'Mainstream' cluster, a higher proportion of those born in 1970 appeared to have drunk alcohol above the contemporaneous UK recommended limits but consumed sweet foods less frequently, than those born in 1958. In summary our findings provide additional evidence of HRB clustering, identifying largely consistent HRBs cluster patterns across cohort and gender groups, with some differences in prevalence. This evidence of HRB clustering across time and by gender provides a person-centred understanding that can inform interventions to improve HRBs

Social influences on health-related behaviour clustering during adulthood in two British birth cohort studies

Building upon evidence linking socio-economic position (SEP) in childhood and adulthood with health-related behaviours (HRB) in adulthood, we examined how pre-adolescent SEP predicted membership of three HRB clusters: “Risky”, “Moderate Smokers” and “Mainstream” (the latter pattern consisting of more beneficial HRBs), that were detected in our previous work. Data were taken from two British cohorts (born in 1958 and 1970) in pre-adolescence (age 11 and 10, respectively) and adulthood (age 33 and 34). SEP constructs in pre-adolescence and adulthood were derived through Confirmatory Factor Analysis. Conceptualised paths from pre-adolescent SEP to HRB cluster membership via adult SEP in our path models were tested for statistical significance separately by gender and cohort. Adult SEP mediated the path between pre-adolescent SEP and adult HRB clusters. More disadvantaged SEP in pre-adolescence predicted more disadvantaged SEP in adulthood which was associated with membership of the “Risky” and “Moderate Smokers” clusters compared to the “Mainstream” cluster. For example, large positive indirect effects between pre-adolescent SEP and adult HRB via adult SEP were present (coefficient 1958 Women = 0.39; 1970 Women = 0.36, 1958 Men = 0.51; 1970 Men = 0.39; p < 0.01) when comparing “Risky” and “Mainstream” cluster membership. Amongst men we found a small significant direct association (p < 0.001) between pre-adolescent SEP and HRB cluster membership. Our findings suggest that associations between adult SEP and HRBs are not likely to be pre-determined by earlier social circumstances, providing optimism for interventions relevant to reducing social gradients in HRBs. Observing consistent findings across the cohorts implies the social patterning of adult lifestyles may persist across time

The relationship between vapour pressure excess and air change rates in bedrooms : a pilot study

Air change rates can be measured using tracer gas techniques which can be costly and intrusive. Moisture data is more accessible, and there is a relationship between moisture conditions and ventilation. This study aims to investigate the relationship between vapour pressure excess and air change rates in bedrooms. The CO2 decay method was used to estimate air change rates when bedrooms were unoccupied in the morning. The relationship between the average hourly change in vapour pressure excess and the air change rate was examined. Results showed a very weak to no correlation between the variables possibly due to moisture buffering and airflow from other rooms

Investigating social influences on and changes in health-related-behaviour clustering during mid-adulthood, using data from two British birth cohort studies

INTRODUCTION: This thesis examines how four health-related behaviours (HRBs) – smoking, alcohol, diet, physical activity – cluster within individuals during mid-adulthood, the relationship between socio-economic position (SEP) in pre-adolescence and mid-adulthood and HRB cluster membership in mid-adulthood and the extent to which mid-adulthood SEP influences change in HRB cluster membership during mid-life. METHODS: The research used datasets from two British birth cohort studies: The National Child Development Study (born in 1958) and the British Birth Cohort study (born in 1970). Latent variable modelling was employed to: (i) identify cross-sectional membership of clusters, who shared patterns of HRBs: (ii) examine changes in cluster membership during mid-life: and iii) validate the relationship between SEP in pre-adolescence and mid-adulthood and HRB cluster membership. RESULTS: Three distinct clustered patterns of HRBs were identified and subsequently labelled: ‘Risky’ (1–9%), ‘Moderate Smokers’ (20–30%) and ‘Mainstream’ (68–77%). The Mainstream cluster was characterised by more health-promoting behavioural patterns, i.e. not smoking, frequent fruit and vegetable consumption, less frequent consumption of chips and fried food, being more physically active, although frequent consumption of sweet foods was common. HRB cluster patterns were largely consistent across cohort and gender groups, with some differences in prevalence. More disadvantaged SEP in pre-adolescence predicted more disadvantaged SEP in mid-adulthood which increased the probability of membership of the ‘Risky’ and ‘Moderate Smokers’ clusters compared to the ‘Mainstream’ cluster. HRB cluster membership was found to be relatively stable during mid-life, although there was evidence of transitions to more health-promoting clusters. These transitions were not influenced by mid-adulthood SEP. DISCUSSION: Consistent findings for the two cohorts imply HRB clustering and their social patterning persists across time and provides a person-centred understanding that can inform interventions to improve HRBs. The contemporaneous influence of mid-adulthood SEP on cluster membership provides optimism, suggesting that mid-adulthood lifestyles may be modifiable

Challenges in developing a moisture metric to assess air change rates

Air change rates are difficult to measure in naturally ventilated buildings. There is incentive to develop alternative techniques to measure air change rates. Using a moisture metric is a possibility, but this is challenging as it requires the ability to quantify processes that affect the moisture balance in a room. This paper consolidates literature about how the moisture balance can be understood in field studies in terms of moisture generation, moisture buffering, and ventilation. Moisture generation rates have been reported in literature with some disparity. Moisture buffering is difficult to account for due to the complexity of the process in real buildings. Ventilation can be measured using tracer gas techniques, but these often provide a ‘snapshot’ of the air change rate which varies both spatially and temporally in buildings. However, a promising approach has been identified whereby moisture and ventilation conditions are examined over a longer period of time i.e. weeks

Comparing relationships between health-related behaviour clustering and episodic memory trajectories in the United States of America and England: a longitudinal study

BACKGROUND: Health-related behaviours (HRBs) cluster within individuals. Evidence for the association between HRB clustering and cognitive functioning is limited. We aimed to examine and compare the associations between three HRB clusters: "multi-HRB cluster", "inactive cluster" and "(ex-)smoking cluster" (identified in previous work based on HRBs including smoking, alcohol consumption, physical activity and social activity) and episodic memory trajectories among men and women, separately, in the United States of America (USA) and England. METHODS: Data were from the waves 10-14 (2010-2018) of the Health and Retirement Study in the USA and the waves 5-9 (2010-2018) of the English Longitudinal Study of Ageing in England. We included 17,750 US and 8,491 English participants aged 50 years and over. The gender-specific HRB clustering was identified at the baseline wave in 2010, including the multi-HRB (multiple positive behaviours), inactive and ex-smoking clusters in both US and English women, the multi-HRB, inactive and smoking clusters in US men, and only the multi-HRB and inactive clusters in English men. Episodic memory was measured by a sum score of immediate and delayed word recall tests across waves. For within country associations, a quadratic growth curve model (age-cohort model, allowing for random intercepts and slopes) was applied to assess the gender-stratified associations between HRB clustering and episodic memory trajectories, considering a range of confounding factors. For between country comparisons, we combined country-specific data into one pooled dataset and generated a country variable (0 = USA and 1 = England), which allowed us to quantify between-country inequalities in the trajectories of episodic memory over age across the HRB clusters. This hypothesis was formally tested by examining a quadratic growth curve model with the inclusion of a three-way interaction term (age × HRB clustering × country). RESULTS: We found that within countries, US and English participants within the multi-HRB cluster had higher scores of episodic memory than their counterparts within the inactive and (ex-)smoking clusters. Between countries, among both men and women within each HRB cluster, faster declines in episodic memory were observed in England than in the USA (e.g., b England versus the USA for men: multi-HRB cluster = -0.05, 95%CI: -0.06, -0.03, b England versus the USA for women: ex-smoking cluster = -0.06, 95%CI: -0.07, -0.04). Additionally, the range of mean memory scores was larger in England than in the USA when comparing means between two cluster groups, including the range of means between inactive and multi-HRB cluster for men (b England versus the USA = -0.56, 95%CI: -0.85, -0.27), and between ex-smoking and multi-HRB cluster for women (b England versus the USA = -1.73, 95%CI: -1.97, -1.49). CONCLUSIONS: HRB clustering was associated with trajectories of episodic memory in both the USA and England. The effect of HRB clustering on episodic memory seemed larger in England than in the USA. Our study highlighted the importance of being aware of the interconnections between health behaviours for a better understanding of how these behaviours affect cognitive health. Governments, particularly in England, could pay more attention to the adverse effects of health behaviours on cognitive health in the ageing population

Ventilation Performance and Hygrothermal Conditions in New-build UK Housing

Providing a high quality indoor environment is important to protect occupant’s health and well-being, particularly in the home where we spend a significant amount of time. This paper explores indoor environmental conditions in mechanically and naturally ventilated new-build low-energy housing in the UK. Indoor air temperature, relative humidity and carbon dioxide data were collated and analysed from 53 dwellings across 20 different new-build demonstration projects (consisting of public and private developments). The results raise concerns regarding ventilation performance in new-build homes, particularly homes with natural/mechanical extract ventilation (MEV). Significantly less variation of temperature and relative humidity levels were observed in homes with balanced mechanical ventilation with heat recovery systems (p=<0.001), suggesting these systems may help to provide a more stable indoor hygrothermal environment. Average indoor air relative humidity levels were consistently higher in MVHR dwellings. The findings suggest that the type of ventilation strategy can play a significant role in regulating indoor relative humidity and air temperature in new- build thermally efficient homes

Design factors affecting the passive release of tracer gas for ventilation measurements

The ventilation rate is an important parameter for assessing indoor air quality and energy efficiency. In occupied buildings, ventilation measurements utilising passive methods are preferable to active methods due to their simplicity and less intrusive nature. The perfluorocarbon tracer method can be used to measure long-term ventilation rates for this purpose. This method requires the passive release of a tracer gas which is often a liquid chemical diffusing out of a vial. The tracer gas emission rate is a key parameter of the vial design as if it is too low, the sampler will not be able to detect the tracer gas. If the emission rate is too high, the sampler can become saturated. Both scenarios will lead to inaccurate ventilation results. There is wide variability in vial design but little information about the relative impact of each design factor. Thus, the aim of this study was to compare the emission rate of a common tracer gas, perfluoromethylcyclohexane, using different vials designs i.e. capping styles, septa materials, and fill levels. Samples were kept in an incubator and gravimetric analysis was carried out using a semi-microbalance (resolution: 0.01 mg). The results demonstrate that the emission rate is significantly affected by capping style but not by fill level

Characterising the actual performance of domestic mechanical ventilation and heat recovery systems

This paper describes the findings and recommendations of a meta-study examining the actual in-use performance of whole-house mechanical ventilation heat recovery systems (MVHR) installed in 54 low energy dwellings in the UK, as part of a national research programme. The performance of the systems is assessed using monitored data on indoor air quality (temperature, relative humidity, CO2) and energy use, cross-related with actual experiences of operating these systems through resident surveys. Design/research team interviews were also used to ascertain the reasons for selecting MVHR as a ventilation strategy for a housing development. Cross-analysis of the quantitative and qualitative data helps to identify the key features of MVHR systems with respect to quality of design, installation and commissioning procedures. Overall the study indicates that the rationale behind the use of MVHR systems is borne out – the rates of ventilation as evidenced very generally by CO2 levels are better, and the energy use overall is lower. However the study also highlights the prevalence of sub-optimal systems and the possible implications on both energy efficiency and indoor air quality. This would lead to houses being naturally ventilated, but relying entirely on opening windows where there is no provision for background ventilation. In some spaces where this is not possible (for example due to external factors such as noise or security), or where there is less adaptive behaviour (for example bedrooms overnight), very poor levels of ventilation are experienced. In general the energy consumption in houses with MVHR systems was lower, but this needs to be contextualised – 77% of the MVHR dwellings with energy data were of Passivhaus construction, which in general have lower consumption within the domestic sample (albeit with MVHR as a key component). In some cases it was found that MVHR systems were selected to achieve compliance with the Code for Sustainable Homes, without much understanding of required air-tightness of the building envelope or the maintenance requirements of these systems. Key recommendations include better understanding of the design issues to ensure good airflow and avoid installation problems associated with ductwork; designing in maintenance requirements including unit location, filter cleaning and replacement; ensuring good communication of the design details with installers and commissioners in conjunction with better quality control onsite; along with improved handover processes and occupant guidance

Meta-analysis of indoor temperatures in new-build housing

Despite growing concerns about overheating, a lack of evidence exists on the scale of the problem, particularly in contemporary UK housing. This paper presents the results of a meta-analysis of indoor temperatures in selected low-energy housing. Temperature data recorded at five-minute intervals in 60 dwellings across 19 demonstration projects (2012–14) were collated and analysed to investigate the prevalence of overheating. Findings evidence high summertime temperatures, with 27% of living rooms exceeding 28°C during August. Based on the Chartered Institution of Building Services Engineers (CIBSE) threshold of 5% annual occupied hours > 25°C, 57% of bedrooms and 75% of living rooms were classified as having overheated. Overall, 30% of living rooms exceeded the adaptive comfort threshold of > 3% occupied hours ΔT ≥ 1 K. The results suggest a fundamental relationship between ventilation and indoor temperatures. The higher minimum and average summertime temperatures observed in mechanical ventilation with heat recovery (MVHR) homes (p < 0.05) and lower temperature range (p < 0.001) suggest the need for greater attention to adequate summertime ventilation provision in airtight homes. The results demonstrate a high prevalence of overheating in exemplary housing, indicating the need for greater efforts to ensure the effective implementation of strategies to minimize overheating and improve ventilation in low-energy homes