Healthy Cities of Tomorrow: the Case for Large Scale Built Environment-Health Studies

Exploring the nexus of urban form, transport, environment and health in large-scale urban studies: A state-of-the-art scoping review

BACKGROUND

As the world becomes increasingly urbanised, there is recognition that public and planetary health relies upon a ubiquitous transition to sustainable cities. Disentanglement of the complex pathways of urban design, environmental exposures, and health, and the magnitude of these associations, remains a challenge. A state-of-the-art account of large-scale urban health studies is required to shape future research priorities and equity- and evidence-informed policies.

OBJECTIVES

The purpose of this review was to synthesise evidence from large-scale urban studies focused on the interaction between urban form, transport, environmental exposures, and health. This review sought to determine common methodologies applied, limitations, and future opportunities for improved research practice.

METHODS

Based on a literature search, 2958 articles were reviewed that covered three themes of: urban form; urban environmental health; and urban indicators. Studies were prioritised for inclusion that analysed at least 90 cities to ensure broad geographic representation and generalisability. Of the initially identified studies, following expert consultation and exclusion criteria, 66 were included.

RESULTS

The complexity of the urban ecosystem on health was evidenced from the context dependent effects of urban form variables on environmental exposures and health. Compact city designs were generally advantageous for reducing harmful environmental exposure and promoting health, with some exceptions. Methodological heterogeneity was indicative of key urban research challenges; notable limitations included exposure and health data at varied spatial scales and resolutions, limited availability of local-level sociodemographic data, and the lack of consensus on robust methodologies that encompass best research practice.

CONCLUSION

Future urban environmental health research for evidence-informed urban planning and policies requires a multi-faceted approach. Advances in geospatial and AI-driven techniques and urban indicators offer promising developments; however, there remains a wider call for increased data availability at local-levels, transparent and robust methodologies of large-scale urban studies, and greater exploration of urban health vulnerabilities and inequities.

Association of greenspace and natural environment with brain volumes mediated by lifestyle and biomarkers among urban residents

OBJECTIVES

To examine the associaiton between environmental measures and brain volumes and its potential mediators.

STUDY DESIGN

This was a prospective study.

METHODS

Our analysis included 34,454 participants (53.4% females) aged 40-73 years at baseline (between 2006 and 2010) from the UK Biobank. Brain volumes were measured using magnetic resonance imaging between 2014 and 2019.

RESULTS

Greater proximity to greenspace buffered at 1000 m at baseline was associated with larger volumes of total brain measured 8.8 years after baseline assessment (standardized β (95% CI) for each 10% increment in coverage: 0.013(0.005,0.020)), grey matter (0.013(0.006,0.020)), and white matter (0.011(0.004,0.017)) after adjustment for covariates and air pollution. The corresponding numbers for natural environment buffered at 1000 m were 0.010 (0.004,0.017), 0.009 (0.004,0.015), and 0.010 (0.004,0.016), respectively. Similar results were observed for greenspace and natural environment buffered at 300 m. The strongest mediator for the association between greenspace buffered at 1000 m and total brain volume was smoking (percentage (95% CI) of total variance explained: 7.9% (5.5-11.4%)) followed by mean sphered cell volume (3.3% (1.8-5.8%)), vitamin D (2.9% (1.6-5.1%)), and creatinine in blood (2.7% (1.6-4.7%)). Significant mediators combined explained 18.5% (13.2-25.3%) of the association with total brain volume and 32.9% (95% CI: 22.3-45.7%) of the association with grey matter volume. The percentage (95% CI) of the association between natural environment and total brain volume explained by significant mediators combined was 20.6% (14.7-28.1%)).

CONCLUSIONS

Higher coverage percentage of greenspace and environment may benefit brain health by promoting healthy lifestyle and improving biomarkers including vitamin D and red blood cell indices.

Education is power: preserving cognition in the UK biobank

Introduction

Dementia is a debilitating syndrome characterized by the gradual loss of memory and cognitive function. Although there are currently limited, largely symptomatic treatments for the diseases that can lead to dementia, its onset may be prevented by identifying and modifying relevant life style risk factors. Commonly described modifiable risk factors include diet, physical inactivity, and educational attainment. Importantly, however, to maximize the utility of our understanding of these risk factors, tangible and meaningful changes to policy must also be addressed.

Objectives

Here, we aim to identify the mechanism(s) by which educational attainment influences cognition.

Methods

We investigated data from 502,357 individuals (Mage = 56.53, SDage = 8.09, 54.40% female) from the UK Biobank cohort via Structural Equation Modelling to illustrate links between predictor variables (i.e., Townsend Deprivation Index, coastal distance, greenspace, years of education), covariates (i.e., participant age) and cognitive function as outcome variables (i.e., pairs-matching, trail-making task B, fluid intelligence).

Results

Our model demonstrated that higher education was associated with better cognitive performance (ps < 0.001), and this relationship was mediated by indices of deprivation, and coastal distance.

Conclusion

Accordingly, our model evinces the mediating effect of socioeconomic and environmental factors on the relationship between years of education and cognitive function. These results further demonstrate the utility and necessity of adapting public policy to encourage equitable access to education and other supports in deprived areas.

Associations of Urban Built Environment with Cardiovascular Risks and Mortality: a Systematic Review

With rapid urbanization, built environment has emerged as a set of modifiable factors of cardiovascular disease (CVD) risks. We conducted a systematic review to synthesize evidence on the associations of attributes of urban built environment (e.g. residential density, land use mix, greenness and walkability) with cardiovascular risk factors (e.g. hypertension and arterial stiffness) and major CVD events including mortality. A total of 63 studies, including 31 of cross-sectional design and 32 of longitudinal design conducted across 21 geographical locations and published between 2012 and 2023 were extracted for review. Overall, we report moderately consistent evidence of protective associations of greenness with cardiovascular risks and major CVD events (cross-sectional studies: 12 of 15 on hypertension/blood pressure (BP) and 2 of 3 on arterial stiffness; and longitudinal studies: 6 of 8 on hypertension/BP, 7 of 8 on CVD mortality, 3 of 3 on ischemic heart disease mortality and 5 of 8 studies on stroke hospitalization or mortality reporting significant inverse associations). Consistently, walkability was associated with lower risks of hypertension, arterial stiffness and major CVD events (cross-sectional studies: 11 of 12 on hypertension/BP and 1 of 1 on arterial stiffness; and longitudinal studies: 3 of 6 on hypertension/BP and 1 of 2 studies on CVD events being protective). Sixty-seven percent of the studies were rated as "probably high" risk of confounding bias because of inability to adjust for underlying comorbidities/family history of diseases in their statistical models. Forty-six percent and 14% of the studies were rated as "probably high" risk of bias for exposure and outcome measurements, respectively. Future studies with robust design will further help elucidate the linkages between urban built environment and cardiovascular health, thereby informing planning policies for creating healthy cities.

Impact of urban green space on self-rated health: Evidence from Beijing

As a crucial component of urban green space (UGS), urban parks have been found to be closely associated with the health of urban residents. Drawing on a large-scale survey, "International First-class Harmonious and Livable Capital", in Beijing conducted in 2018, this paper examines the impact of subjective and objective characteristics of UGS on residents' self-rated health (SRH) by using a binary logistic regression model. The results indicate that the overall SRH status of urban residents in Beijing is relatively good, with 73.8% of the respondents reporting good SRH. The perceived quality of UGS and objectively measured accessibility to UGS are positively associated with residents' SRH, but the subjective indicator of UGS has a greater impact on SRH than the objective indicator of UGS. In terms of influencing mechanisms, social interaction and air quality perception were the two major mediators of UGS that affected residents' SRH. The heterogeneity analysis suggests that objective accessibility to different types of urban parks has mixed effects on residents' SRH. Access to high-quality parks is positively associated with residents' SRH, whereas access to common parks has a negative impact on residents' SRH. Our findings provide important policy implications for optimizing urban park design and improving the quality of urban park provision according to human needs in the Beijing Metropolitan Area.

Climate to COVID, global to local, policies to people: a biopsychosocial ecological framework for syndemic prevention and response in behavioral medicine

Land development, pollution, and waste have affected natural environments, contributing to hurricanes, wildfires, and pandemic infectious diseases like COVID-19. Globalized corporate food systems that produce ultra-refined foods with low nutritional value contribute to both environmental conditions and health conditions like obesity and undernutrition. This has the greatest impact on communities already suffering from elevated health risks driven by economic inequities rooted in racism. These interacting environmental, health, and social conditions represent a syndemic. We outline practical suggestions to address this syndemic of environmental degradation, pandemic infectious disease, chronic disease, undernutrition, and inequity through research and practice at many levels, including individual behavior, local communities, and regional, national and global policy. Collaboration with communities is central to simultaneously tackling interconnected human and environmental health threats. For example, community-led groups have increased access to healthy food in response to pandemic conditions. Building on behavioral medicine's rich foundation of ecological models, communities have partnered with local researchers to address the needs of equitable public transport and reduction of greenhouse gas emissions through multilevel research and practice. Policymakers, researchers, practitioners, and community members should collaborate with each other and across disciplines to find lasting, multiduty solutions to improve physical, psychosocial, and planetary health.

Developing a Health-Spatial Indicator System for a Healthy City in Small and Midsized Cities

A recent examination of the significant role of public health has prompted calls to re-investigate how the urban environment affects public health. A vital part of the solution includes Healthy City initiatives that have been the subject of extensive policies, implications, and practices globally. However, the existing literature mainly focuses on big cities and metropolitan areas, while investigations into small and midsized cities (SMCs) are lacking, and thus reflect the underlying issues of health inequity. This study develops an indicator system for evaluating Healthy City initiatives in SMCs, linking urban design and public health, supported by the analyzed opinions from experts collected using both questionnaires and interviews. The indicator system includes six primary dimensions and 37 variables: urban form and transportation (UFT); health-friendly service (HFS); environmental quality and governance (EQG); community and facility (CF); green and open space (GOS); and ecological construction and biodiversity (ECB). A fuzzy synthetic evaluation technique was used to assess the relative importance of factors, emphasizing the importance of UFT, HFS, and EQG, with importance indexes of 0.175, 0.174, and 0.174, respectively. This indicator system is helpful for SMCs seeking to construct a Healthy City in the future, and is based on urban design and governance inputs and for enhancing the Healthy City knowledge base of cities of varied scales.

Investigating the Association between Environmental Quality Characteristics and Mental Well-Being in Public Open Spaces

The issues related to the urban environment and mental well-being have become increasingly important in recent decades. Although this association has been mainly investigated in developed countries, there is limited knowledge on whether similar results can be acquired in the urban environments of developing countries like Iran. This study intends to present a new dynamic and active approach to determine the environmental quality characteristics that influence the mental well-being of urban residents and to engage people to healthy urban public environments. In this respect, the research is directed by both qualitative and quantitative surveys in the public open spaces of Kermanshah, Iran. Firstly, the data are collected by Grounded Theory (GT) to identify significant environmental quality characteristics related to mental well-being by applying 24 semi-structured interviews. Secondly, the questionnaire survey based on Structural Equation Modeling (SEM) is applied to examine the association between each characteristic of the developed conceptual framework. The results reveal that the environmental quality characteristics of public open spaces, directly and indirectly, relate to users’ mental well-being. It should be noted that the public open spaces with unique functional and intrinsic features seem to have different impacts on mental well-being.

Assessing Trade-Offs and Optimal Ranges of Density for Life Expectancy and 12 Causes of Mortality in Metro Vancouver, Canada, 1990-2016

Background: Understanding and managing the impacts of population growth and densification are important steps for sustainable development. This study sought to evaluate the health trade-offs associated with increasing densification and to identify the optimal balance of neighbourhood densification for health. Methods: We linked population density with a 27-year mortality dataset in Metro Vancouver that includes census-tract levels of life expectancy (LE), cause-specific mortalities, and area-level deprivation. We applied two methods: (1) difference-in-differences (DID) models to study the impacts of densification changes from the early 1990s on changes in mortality over a 27-year period; and (2) smoothed cubic splines to identify thresholds of densification at which mortality rates accelerated. Results: At densities above ~9400 persons per km², LE began to decrease more rapidly. By cause, densification was linked to decreased mortality for major causes of mortality in the region, such as cardiovascular diseases, neoplasms, and diabetes. Greater inequality with increasing density was observed for causes such as human immunodeficiency virus and acquired immunodeficiency syndrome (HIV/AIDS), sexually transmitted infections, and self-harm and interpersonal violence. Conclusions: Areas with higher population densities generally have lower rates of mortality from the major causes, but these environments are also associated with higher relative inequality from largely preventable causes of death.

Scaling of mortality in 742 metropolitan areas of the Americas

We explored how mortality scales with city population size using vital registration and population data from 742 cities in 10 Latin American countries and the United States. We found that more populated cities had lower mortality (sublinear scaling), driven by a sublinear pattern in U.S. cities, while Latin American cities had similar mortality across city sizes. Sexually transmitted infections and homicides showed higher rates in larger cities (superlinear scaling). Tuberculosis mortality behaved sublinearly in U.S. and Mexican cities and superlinearly in other Latin American cities. Other communicable, maternal, neonatal, and nutritional deaths, and deaths due to noncommunicable diseases were generally sublinear in the United States and linear or superlinear in Latin America. Our findings reveal distinct patterns across the Americas, suggesting no universal relation between city size and mortality, pointing to the importance of understanding the processes that explain heterogeneity in scaling behavior or mortality to further advance urban health policies.

The Built Environment and Health in Low- and Middle-Income Countries: a Review on Quantitative Health Impact Assessments

PURPOSE OF REVIEW

Features and attributes of the built environment (BE) impact positively and negatively on health, especially in cities facing unprecedented urban population growth and mass motorization. A common approach to assess the health impacts of built environment is health impact assessment (HIA), but it is rarely used in low- and middle-income countries (LMICs) where urbanization rates are fastest. This article reviews selected HIA case studies from LMICs and reports the methods and tools used to support further implementation of quantitative HIAs in cities of LMICs.

RECENT FINDINGS

In total, 24 studies were reviewed across Algeria, Brazil, China, India, Iran, Kenya, Thailand, Turkey, and Mauritius. HIAs examine specific pathways through which the built environment acts: air pollution, noise, physical activity, and traffic injury. Few HIAs of BE addressed more than one exposure pathway at a time, and most studies focused on air pollution across the sectors of transport and energy. A wide number of tools were used to conduct exposure assessment, and different models were applied to assess health impacts of different exposures. Those HIAs rely on availability of local concentration data and often use models that have set exposure-response functions (ERFs). ERFs were not adapted to local populations except for HIAs conducted in China. HIAs of BE are being successfully conducted in LMICs with a variety of tools and datasets. Scaling and expanding quantitative health impact modeling in LMICs will require further study on data availability, adapted models/tools, low technical capacity, and low policy demand for evidence from modeling studies. As case studies with successful use of evidence from modeling emerge, the uptake of health impact modeling of BE is likely to increase in favor of people and planet.

Business Data Categorization and Refinement for Application in Longitudinal Neighborhood Health Research: a Methodology

Retail environments, such as healthcare locations, food stores, and recreation facilities, may be relevant to many health behaviors and outcomes. However, minimal guidance on how to collect, process, aggregate, and link these data results in inconsistent or incomplete measurement that can introduce misclassification bias and limit replication of existing research. We describe the following steps to leverage business data for longitudinal neighborhood health research: re-geolocating establishment addresses, preliminary classification using standard industrial codes, systematic checks to refine classifications, incorporation and integration of complementary data sources, documentation of a flexible hierarchical classification system and variable naming conventions, and linking to neighborhoods and participant residences. We show results of this classification from a dataset of locations (over 77 million establishment locations) across the contiguous U.S. from 1990 to 2014. By incorporating complementary data sources, through manual spot checks in Google StreetView and word and name searches, we enhanced a basic classification using only standard industrial codes. Ultimately, providing these enhanced longitudinal data and supplying detailed methods for researchers to replicate our work promotes consistency, replicability, and new opportunities in neighborhood health research.

Residential greenness and indicators of stress and mental well-being in a Canadian national-level survey

BACKGROUND

Residential proximity to greenness in urban areas has been shown to confer a number of health benefits, including improved mental health. We investigated whether greenness was associated with self-reported stress, distress, and mental health among adult participants of multiple cycles of a national Canadian health survey, and whether these associations varied by sex, age, income, and neighbourhood characteristics.

METHODS

Our study population included 397,900 participants of the Canadian Community Health Survey, 18 years of age or older, who lived in census metropolitan areas between 2000 and 2015. We used the Normalized Difference Vegetation Index (NDVI) to characterize participants' exposure to greenness within 250 m, 500 m, and 1 km buffers from a representative location of their postal code. Health outcomes included: self-reported perceptions of life stress, psychological distress, and self-rated mental health. We used multiple regression models, adjusted for relevant individual and neighbourhood-level variables to estimate associations (and 95% confidence intervals) between each outcome and exposure to greenness.

FINDINGS

In models with all participants, we observed 6% lower odds of poor self-rated mental health per increase in the interquartile range (i.e., 0.12) of NDVI within a 500 m buffer. Across the three outcomes, we found substantial heterogeneity in effect size across categories of sex, age, and community-level indicators of deprivation and urban form. For example, each incremental increase in greenness exposure was associated with a reduction of 0.61 (95% CI: 0.81 to -0.51) on the K10 psychological distress score among those living in the active core of cities, and with an increase of 0.07 (95% CI: 0.03-0.12) on this score among those living in the most suburban areas.

CONCLUSIONS

Our results indicate that the potential benefits of residential greenness on mental health vary across personal and neighbourhood-level characteristics and are sensitive to how the outcome is measured. Additional research is needed to understand which features of greenness are most relevant to different sub-groups of the population to maximize these health benefits.

Does Compact Built Environment Help to Reduce Obesity? Influence of Population Density on Waist-Hip Ratio in Chinese Cities

This study aimed to identify the non-linear association between population density and obesity in China and to provide empirical evidence for the public health orientated guideline of urban planning. By conducting a longitudinal study with data collected from the China Health and Nutrition Survey (CHNS) between 2004 and 2011, we applied fixed-effect models to assess the non-linear association between the compact built environment and waist–hip ratio (WHR), controlling for sex, age, nationality, education, employment status, marital status, household size, household income, and residents’ attitudes. Our findings reveal that the built environment is one of the key determinants of obesity. The U-shaped influence of population density on WHR was observed. Moreover, influence differs according to sex and weight status. Our findings indicate healthy city planning has the potential to improve the built environment to reduce obesity risk and promote public health.

The nature of cities and the Covid-19 pandemic

The virtual issue will only include the main essay.

Recent Literature about Urban Sprawl: A Renewed Relevance of the Phenomenon from the Perspective of Environmental Sustainability

The urban sprawl phenomenon has attracted the attention of social researchers since the mid-20th century. It seemed that all relevant aspects had been extensively studied and that it would be difficult to produce new studies with significant contributions. However, in the last decade, we have witnessed a revival of the literature on urban sprawl for three main reasons: (i) the existence of new methodologies to measure the phenomenon based on digital cartography and geo-referenced information, (ii) new hypotheses about the relevance of the formation of metropolitan areas not institutionally integrated into urban sprawl in many places and, mainly, (iii) the role of urban density in the environmental sustainability of cities. The recent literature on this third aspect has grown the most and around which it seems that new and interesting lines of future research will develop. The objective of this work is to present a synthetic review of the most recent literature on urban sprawl as of the end of the second decade of the XXI century. This review can serve to recapitulate the growing consensus that is being formed on the lower environmental sustainability of low-density cities and diffuse limits.

Dynamic Urban Environmental Exposures on Depression and Suicide (NEEDS) in the Netherlands: a protocol for a cross-sectional smartphone tracking study and a longitudinal population register study

INTRODUCTION

Environmental exposures are intertwined with mental health outcomes. People are exposed to the environments in which they currently live, and to a multitude of environments along their daily movements and through their residential relocations. However, most research assumes that people are immobile, disregarding that such dynamic exposures also serve as stressors or buffers potentially associated with depression and suicide risk. The aim of the Dynamic Urban Environmental Exposures on Depression and Suicide (NEEDS) study is to examine how dynamic environmental exposures along people's daily movements and over their residential histories affect depression and suicide mortality in the Netherlands.

METHODS AND ANALYSIS

The research design comprises two studies emphasising the temporality of exposures. First, a cross-sectional study is assessing how daily exposures correlate with depression. A nationally representative survey was administered to participants recruited through stratified random sampling of the population aged 18-65 years. Survey data were enriched with smartphone-based data (eg, Global Positioning System tracking, Bluetooth sensing, social media usage, communication patterns) and environmental exposures (eg, green and blue spaces, noise, air pollution). Second, a longitudinal population register study is addressing the extent to which past environmental exposures over people's residential history affect suicide risk later in life. Statistical and machine learning-based models are being developed to quantify environment-health relations.

ETHICS AND DISSEMINATION

Ethical approval (FETC17-060) was granted by the Ethics Review Board of Utrecht University, The Netherlands. Project-related findings will be disseminated at conferences and in peer-reviewed journal papers. Other project outcomes will be made available through the project's web page, http://www.needs.sites.uu.nl.

The impact of the built environment on health behaviours and disease transmission in social systems

The environment plays an important role in disease dynamics and in determining the health of individuals. Specifically, the built environment has a large impact on the prevention and containment of both chronic and infectious disease in humans and in non-human animals. The effects of the built environment on health can be direct, for example, by influencing environmental quality, or indirect by influencing behaviours that impact disease transmission and health. Furthermore, these impacts can happen at many scales, from the individual to the society, and from the design of the plates we eat from to the design of cities. In this paper, we review the ways that the built environment affects both the prevention and the containment of chronic and infectious disease. We bring examples from both human and animal societies and attempt to identify parallels and gaps between the study of humans and animals that can be capitalized on to advance the scope and perspective of research in each respective field. By consolidating this literature, we hope to highlight the importance of built structures in determining the complex dynamics of disease and in impacting the health behaviours of both humans and animals.This article is part of the theme issue 'Interdisciplinary approaches for uncovering the impacts of architecture on collective behaviour'.

Residential greenness and prevalence of major depressive disorders: a cross-sectional, observational, associational study of 94 879 adult UK Biobank participants

BACKGROUND

Increased urbanisation and the associated reduced contact of individuals with natural environments have led to a rise in mental disorders, including depression. Residential greenness, a fundamental component of urban design, has been shown to reduce the public health burden of mental disorders. The present study investigates the association between residential green exposure and prevalence of major depressive disorders using a large and diverse cross-sectional dataset from the UK Biobank.

METHODS

In this cross-sectional, observational, associational study, we used baseline data from the UK Biobank cohort of participants aged 37-73 years from across the UK. Environmental exposure data were derived from a modelled and linked built environment database. Residential greenness was assessed with a 0·5 m resolution Normalised Difference Vegetation Index, which is derived from spectral reflectance measurements in remotely sensed colour infrared data and measured within geocoded dwelling catchments. Other environment metrics included street-level movement density, terrain, and fine particulate exposures. A series of logistic models examined associations between residential greenness and odds of major depressive disorder after adjusting for activity-influencing environments and individual covariates.

FINDINGS

Of 122 993 participants with data on major depressive disorder, the study analytical sample comprised 94 879 (77·1%) participants recruited across ten UK Biobank assessment centres between April 29, 2009, and Oct 1, 2010. A protective effect of greenness on depression was consistently observed, with 4·0% lower odds of major depressive disorder per interquartile increment in Normalised Difference Vegetation Index greenness (odds ratio 0·960, 95% CI 0·93-0·99; p=0·0044). Interaction analyses indicated that the beneficial effects of greenness were more pronounced among women, participants younger than 60 years, and participants residing in areas with low neighbourhood socioeconomic status or high urbanicity.

INTERPRETATION

The results point to the benefits of well designed green environments on mental health. Further longitudinal studies are needed to decipher causal pathways. In the UK, policies aimed at optimising allocation and design of green spaces might help preserve psychological ecosystem services, thereby, improving the mental wellbeing of populations and enhancing the mental capital of cities.

FUNDING

University of Hong Kong, UK Biobank, and the UK Economic & Social Research Council.

Neighbourhood walkability and incidence of hypertension: Findings from the study of 429,334 UK Biobank participants

BACKGROUND

With an estimated one billion hypertension cases worldwide, the role of the built environment in its prevention and control is still uncertain. The present study aims to examine the associations between neighbourhood walkability and hypertension in a large and diverse population-based cohort.

MATERIALS AND METHODS

We examined the association between neighbourhood walkability and blood pressure outcomes for N = 429,334 participants drawn from the UK Biobank and aged 38-73 years. Neighbourhood walkability was objectively modelled from detailed building footprint-level data within multi-scale functional neighbourhoods (1.0-, 1.5- and 2.0-kilometer street catchments of geocoded dwelling). A series of linear and modified Poisson regression models were employed to examine the association between walkability and outcomes of diastolic blood pressure (DBP in mmHg), systolic blood pressure (SBP in mmHg) and prevalent hypertension adjusting for socio-demographic, lifestyle and related physical environmental covariates. We also examined the relationship between walkability and change in blood pressure for a sub-sample of participants with follow-up data and tested for interaction effects of age, sex, employment status, neighbourhood SES, residential density and green exposure.

RESULTS

Neighbourhood walkability within one-kilometer street catchment was beneficially associated with all the three blood pressure outcomes, independent of all other factors. Each interquartile increment in walkability was associated with the lower blood pressure outcomes of DBP (β = -0.358, 95% CI: -0.42, -0.29 mmHg), SBP (β = -0.833, 95% CI: -0.95, -0.72 mmHg) as well as reduced hypertension risk (RR = 0.970, 95% CI: 0.96, 0.98). The results remained consistent across spatial and temporal scales and were sensitive to sub-groups, with pronounced protective effects among female participants, those aged between 50 and 60 years, in employment, residing in deprived, high density and greener areas.

CONCLUSION

This large population-based cohort found evidence of protective association between neighbourhood walkability and blood pressure outcomes. Given the enduring public health impact of community design on individual behaviour and lifestyle, of particular interest, are the targetted upstream-level interventions in city design aimed at optimizing walkability. Further long term studies are required to assess its sustained effects upon hypertension prevention and control.

Toward dynamic urban environmental exposure assessments in mental health research

It is increasingly recognized that mental disorders are affected by both personal characteristics and environmental exposures. The built, natural, and social environments can either contribute to or buffer against metal disorders. Environmental exposure assessments related to mental health typically rely on neighborhoods within which people currently live. In this article, I call into question such neighborhood-based exposure assessments at one point in time, because human life unfolds over space and across time. To circumvent inappropriate exposure assessments and to better grasp the etiologies of mental disease, I argue that people are exposed to multiple health-supporting and harmful exposures not only during their daily lives, but also over the course of their lives. This article aims to lay a theoretical foundation elucidating the impact of dynamic environmental exposures on mental health outcomes. I examine, first, the possibilities and challenges for mental health research to integrate people's environmental exposures along their daily paths and, second, how exposures over people's residential history might affect mental health later in life. To push the borders of scientific inquiries, I stress that only such mobility-based approaches facilitate an exploration of exposure duration, exposure sequences, and exposure accumulation.

Residential greenness and adiposity: Findings from the UK Biobank

BACKGROUND

With the rapid urbanization and prevailing obesity pandemic, the role of residential green exposures in obesity prevention has gained renewed focus. The study investigated the effects of residential green exposures on adiposity using a large and diverse population sample drawn from the UK Biobank.

MATERIALS AND METHODS

This was a population based cross-sectional study of 333,183 participants aged 38-73years with individual-level data on residential greenness and built environment exposures. Residential greenness was assessed through 0.50-metre resolution normalized difference vegetation index (NDVI) derived from spectral reflectance measurements in remotely sensed colour infrared data and measured around geocoded participants' dwelling. A series of continuous and binary outcome models examined the associations between residential greenness and markers of adiposity, expressed as body-mass index (BMI) in kg/m², waist circumference (WC) in cm, whole body fat (WBF) in kg and obesity (BMI≥30kg/m²) after adjusting for other activity-influencing built environment and individual-level confounders. Sensitivity analyses involved studying effect modification by gender, age, urbanicity and SES as well as examining relationships between residential greenness and active travel behaviour.

RESULTS

Residential greenness was independently and consistently associated with lower adiposity, the association being robust to adjustments. An interquartile increment in NDVI greenness was associated with lower BMI (β_BMI=-0.123kg/m², 95% CI: -0.14, -0.10kg/m²), WC (β_WC=-0.551cm, 95% CI: -0.61, -0.50cm), and WBF (β_WBF=-0.138kg, 95% CI: -0.18, -0.10kg) as well as a reduced relative risk of obesity (RR=0.968, 95% CI: 0.96, 0.98). Residential greenness was beneficially related with active travel, being associated with higher odds of using active mode for non-work travel (OR=1.093, 95% CI: 1.08, 1.11) as well as doing >30min walking (OR=1.039, 95% CI: 1.03, 1.05).

CONCLUSION

Residing in greener areas was associated with healthy weight outcomes possibly through a physical activity-related mechanism. Green allocation and design may act as upstream-level public health interventions ameliorating the negative health externalities of obesogenic urban environments. Further prospective studies are needed to identify potential causal pathways and thereby effectively guide such interventions.