Green space and mortality following ischemic stroke

Inequalities in residential green space and trajectory of cardiometabolic multimorbidity: Different associations by sex and socioeconomic status

Residential green space has the potential to benefit cardiometabolic health. However, little is known about its impacts on cardiometabolic multimorbidity (CMM). Furthermore, the capacity of access to green space to reduce health inequalities during the development of CMM is unclear, and longitudinal evidence is urgently needed. Hence, a large prospective study based on the UK Biobank was conducted. CMM was defined as the coexistence of at least two conditions including type 2 diabetes, ischemic heart disease, and stroke. Multi-state models were used to assess the impacts of green space on the transitions of CMM, from free of cardiometabolic disease to first cardiometabolic disease (FCMD), subsequently to CMM, and finally death. This study included 328,260 participants with a median follow-up of 12.5 years. The benefits of access to green space were observed for transitions from baseline to FCMD, from baseline to death, and from FCMD to death, with HRs of 0.975 (95 % CI: 0.959, 0.991), 0.956 (95 % CI: 0.931, 0.982) and 0.943 (95 % CI: 0.897, 0.990) per IQR increase in the percentage of green space, respectively. Although access to green space benefited early transitions related to FCMD, its protective role was not found in the progression from FCMD to CMM and finally death. Furthermore, access to green space was associated with a reduction in health inequalities influenced by sex and socioeconomic status in the earliest transition from healthy to FCMD. Future policies should prioritize green space investments to sustainably enhance cardiometabolic health and improve health inequalities.

Exposure to greenness modifies the association between extreme temperature events and ischemic stroke recurrence in Tianjin, China

Few studies have found an association between extreme temperature events and an increased risk of recurrent ischemic stroke (IS). We examined associations between extreme temperature events (heat waves, cold spells) and recurrent IS risk in Tianjin, China (2019-2020), using a time-stratified case-crossover design, while evaluating greenness's moderating role. Significant heat wave effects peaked at lag 8, with severe intensity events increasing IS recurrence risk by 39.8% (OR = 1.398, 95% CI:1.032-1.894). Cold spell impacts peaked at lag 3, with moderate intensity cold spells elevating risk by 20.3% (OR = 1.203, 95% CI: 1.052-1.377) and severe intensity cold spells elevating risk by 98.2% (OR = 1.982, 95% CI: 1.407-2.791). Greenness modified these associations: low-greenness areas strengthened heat wave effects(lag9:OR = 2.309,95%CI:1.024-5.209) but weakened cold spell impacts(OR = 1.557,95%CI:1.037-2.340), whereas high-greenness areas attenuated heat wave links(lag8:OR = 1.402,95%CI:1.022-1.924) and nullified cold spell associations. Age and sex disparities emerged - younger individuals and males showed higher susceptibility to heat waves, while older individuals and males were more vulnerable to cold spells. The findings highlight greenness as a potential modifier of extreme temperature events-related IS recurrence risks and underscore demographic-specific vulnerabilities.

Association Between Residential Greenness and Risk of Stroke by Ecoregions: The REGARDS Study

BACKGROUND

Living in areas with more greenness has been associated with beneficial health outcomes. However, few studies have examined associations of greenness with incidence of stroke, and it is unclear how these associations may vary with the type of vegetation and surrounding ecology. This study evaluated associations between greenness and incidence of stroke by the major ecological regions in the United States.

METHODS AND RESULTS

We assessed the incidence of stroke in 27 369 participants from the REGARDS (Reasons for Geographic and Racial Differences in Stroke) study, a prospective cohort recruited across the contiguous United States. Greenness was estimated by the normalized difference vegetation index and enhanced vegetation index (EVI) at multiple buffers around home addresses. Participants were assigned to ecoregions using their baseline residence. We estimated the association between residential greenness and incidence of stroke using covariate-adjusted Cox proportional hazards models. Models were stratified by ecoregions to assess how associations varied by areas with unique vegetation and ecology. We observed 1581 incident cases of stroke during the study period. In the full study population, there was suggestive evidence of a protective association between greenness and stroke incidence (hazard ratio [HR], 0.989 [95% CI, 0.946-1.033]) for a 0.1 increase in normalized difference vegetation index within 250 m. Similar results were obtained using enhanced vegetation index and larger radii. In our analysis by ecoregions, we found greenness was associated with lower stroke risk in the Eastern Temperate Forests region (HR, 0.946 [95% CI, 0.898-0.997]), but higher risk in the Great Plains (HR, 1.442 [95% CI, 1.124-1.849]) and Mediterranean California regions (HR, 1.327 [95% CI, 1.058-1.664]).

CONCLUSIONS

Vegetation may lower the risk of stroke; however, benefits may be limited to certain contexts of the natural environment.

Effects of Home Neighborhood Tree Canopy Coverage on Mental Health Outcomes: A Traumatic Brain Injury Model Systems Investigation

OBJECTIVE

Explore the relationship between tree canopy coverage (TCC) in one's home neighborhood and mental health outcomes, and how these relationships differ by home neighborhood factors, among persons with traumatic brain injury (TBI) in the United States.

SETTING

Community.

PARTICIPANTS

Enrolled in the TBI Model Systems National Database with completed follow-up interview after January 1, 2017.

DESIGN

Secondary analysis of cross-sectional data.

MAIN MEASURES

Neighborhood (census tract) Percent TCC, depressive (Patient Health Questionnaire-9) and anxiety (General Anxiety Disorder-7) symptoms (scores ≥10 on each measure), personal/demographic (age, sex, education, homebound status), and neighborhood factors (type, socioeconomic disadvantage).

RESULTS

Separate negative binomial regression models were constructed for the 2 mental health outcomes (depression and anxiety symptoms). Covariates in final models were age, sex, neighborhood type, Functional Independence Measure (FIM) total (concurrent), driving status, homebound status, and neighborhood-level socioeconomic disadvantage. The interaction between Percent TCC and neighborhood type (but not homebound status) was significant for depression and anxiety symptoms. The nature of the significant interaction was such that, for both mental health outcomes, those living in rural neighborhoods with higher Percent TCC were more likely to have moderate to severe mental health symptoms. However, this effect was attenuated after adding neighborhood level socioeconomic disadvantage, suggesting that part of the effect may be due to socioeconomic characteristics of rural versus other neighborhoods.

CONCLUSIONS

After adjusting for SDoH, the direct effect of TCC on mental health after TBI was small and opposite the direction hypothesized (higher TCC associated with poorer mental health), particularly for those living in rural neighborhoods potentially more likely to experience socioeconomic disadvantage. Our findings highlight the importance of evaluating interactions between different aspects of the social (eg, SDoH), natural (eg, greenspace), and built (eg, neighborhood type) environment to provide a comprehensive understanding of factors affecting health after TBI.

Green space is associated with new-onset stroke among Chinese middle-aged and older adults: data from China Health and Retirement Longitudinal Study (CHARLS)

Background and aims

The relationship between green space and new-onset stroke is inconclusive. This study aimed to investigate the association between green space and stroke risk among Chinese middle-aged and older adults.

Methods

Data were taken from participants aged ≥45 years in the China Health and Retirement Longitudinal Study (CHARLS). Baseline data were collected in 2011 and new-onset stroke data were gathered during follow-up in 2013, 2015, 2018, and 2020. Multivariate Cox regression models were constructed to investigate the association between green space and stroke risk. Subgroup analysis was also performed.

Results

A total of 13,696 participants with a mean age of 59.3 ± 9.3 years were included. After a mean follow-up duration of 6.32 years, there were 728 stroke events during a total of 86,530 person-years of follow-up. The study found a L-shaped relationship between green space and the risk of new-onset stroke in participants. By using a two-piecewise linear regression model, we calculated that the inflection point for the per capita park green area was 10.61 square meters per person (log-likelihood ratio test p = 0.041). On the left of the inflection point, we observed a negative relationship between green space and the incidence of stroke (HR: 0.89, 95% CI: 0.84-0.94, p = 0.0001). On the right side of the inflection point, however, the relationship tended to be saturated (HR: 0.97, 95% CI: 0.94-1.01, p = 0.2111).

Conclusion

Our study found that the relationship between green space and the risk of new-onset stroke follows a L-shaped curve. A lower amount of green space is associated with an increased risk of new-onset stroke. These findings require confirmation in future studies.

Interplay Between Residential Nature Exposure and Walkability and Their Association with Cardiovascular Health

Background

Green space has been linked with cardiovascular (CV) health. Nature access and quality may have significant impact on CV risk factors and health.

Objectives

The authors aimed to investigate the relationship between NatureScore, a composite score for natural environment exposure and quality of green spaces, with CV risk factors and atherosclerotic cardiovascular diseases (ASCVD).

Methods

A cross-sectional study including one million adult patients from the Houston Methodist Learning Health System Outpatient Registry (2016-2022). NatureScore is a composite measure of natural environment exposure and quality (0-100) calculated for each patient based on residential address. NatureScores was divided into 4 categories: nature deficient/light (0-39), nature adequate (40-59), nature rich (60-79), and nature utopia (80-100). CV risk factors included hypertension, diabetes, dyslipidemia, and obesity.

Results

Among 1.07 million included patients (mean age 52 years, female 59%, Hispanic 16%, Non-Hispanic Black 14%), median NatureScore was 69.4. After adjusting for neighborhood walkability, patients living in highest NatureScore neighborhoods had lower prevalence of CV risk factors (OR: 0.91, 95% CI: 0.90-0.93) and ASCVD (OR: 0.96, 95% CI: 0.93-0.98) than those in lowest NatureScore neighborhoods. A significant interaction existed between NatureScore and Walkability (P < 0.001), where those in high NatureScore (≥60) high walkability (≥40) areas had lower prevalence of CV risk factors (OR: 0.93, 95% CI: 0.90-0.97, P < 0.001) and were more likely to have optimal CV risk profile (relative risk ratio: 1.09, 95% CI: 1.04-1.14, P = 0.001).

Conclusions

These findings suggest that while green spaces benefit health, their accessibility through walkable environments is crucial for cardiovascular disease protection.

The mortality impacts of greening Italy

Green spaces have been shown to be beneficial to humans, but quantifying these benefits is a challenge for epidemiology. In this health impact assessment study, we exploit satellites to estimate for the whole of Italy the number of deaths that could be prevented in the 49 million adult population by greening residential areas. The exposure was assessed by calculating the normalized difference vegetation index at 10-m resolution within a 300-m distance from homes in 7904 municipalities. In this study we estimate, by achieving nationwide the level of residential greenness currently reached by the 25% of the population, a total of 28,433 (95% confidence interval: 21,400-42,350) preventable deaths and 279,324 (210,247-415,980) preventable years of life lost in Italy in 2022, representing the 5% of the total mortality burden. More green means fewer deaths, thus strong action is needed to increase the amount and accessibility of green spaces in all human settlements.

The impact of green space on nonaccidental and cause-specific mortality in the Adventist Health Study-2 population

Background

There is growing interest in evaluating the long-term health effects of neighborhood environments, particularly green space. However, only a limited body of research further incorporates multiple ambient air pollutants.

Methods

This study looked at the relationship between green space, as measured by the Normalized Difference Vegetation Index, and mortality adjusted by key confounders in the Adventist Health Study-2, a longitudinal cohort study from 2002 to 2015, across the contiguous United States (N = 67,400). We used Cox proportional hazard regression models to assess the risk of nonaccidental, cardiovascular disease (CVD), ischemic heart disease (IHD), and respiratory disease mortality from green space around subjects' home address under multiple covariate and pollutant adjustments.

Results

We found a 0.1 unit increase in the Normalized Difference Vegetation Index was associated with nonaccidental (hazard ratio [HR]: 0.96 [95% confidence interval (CI): 0.93, 0.99]), CVD (HR: 0.94 [95% CI: 0.90, 0.98]), and IHD (HR: 0.87 [95% CI: 0.81, 0.94]) mortality, with the greatest precision in fully adjusted three-pollutant models using the 1000-m buffer. Effect estimates were strengthened in urban areas, when incorporating seasons, and for females. However, all associations between green space and respiratory mortality were null.

Conclusion

This study supports evidence that increased neighborhood green space is inversely associated with nonaccidental, CVD, and IHD mortality, where the inclusion of multiple environmental covariates had a greater impact on effect estimate magnitude and precision than adjustment by individual lifestyle and health factors.

Modifying effects of green space on the relationships between air pollution and ischemic cerebrovascular event recurrence in Tianjin, China

This study aimed to explore how air pollution and green space influence ICE recurrence and whether they might interact with each other. A case-cross design was used in this study, which was carried out in Tianjin, China. A total of 8306 patients with recurrent ICE were collected from 2019 to 2020. The maximum effects of PM2.5, PM10, SO2, NO2, CO were 1.012 (95%CI: 1.004, 1.019), 1.010 (95%CI: 1.004, 1.016), 1.035 (95%CI: 0.982, 1.091), 1.067 (95%CI: 1.043, 1.091) and 1.012 (95%CI: 1.004, 1.021)  , respectively, and the risk was higher in males and in the 50-60 age group. In the stratification of greening, it was found that air pollution except O3 had the highest risk of ICE recurrence for those with lower green space. Our study found that air pollution (except O3) can increase the risk of ICE recurrence, and this risk can be reduced by increasing green space.

Green space and stroke: A scoping review of the evidence

BACKGROUND

Global industrialisation and urbanisation has led to an increased interest in the link between the environment and health. Stroke is a major cause of morbidity and mortality, and there is increased evidence that environmental factors may affect both the incidence and severity of stroke. This review summarises the evidence for relationship between green space exposure and stroke incidence and outcomes.

METHODS

We conducted a literature search in Medline and Scopus until 1 August 2023, and screened references of relevant articles. Selected articles were appraised for their relevance, and critically reviewed. The findings were thematically categorised.

RESULTS

Of the 1342 papers identified, 27 were included. These involved a mix of study designs (cohort, cross-sectional, quasi-experimental, time stratified case crossover and ecological). There was consistent evidence indicating a protective association between green space exposure and disability and stroke-related death with mortality hazard ratios between 0.66 and 0.95. Most studies also showed that green space was inversely associated with stroke risk, with risk estimates from studies showing a protective effect ranging between 0.4 and 0.98; however, results were more mixed and some did not reach statistical significance. The moderating effects of green spaces on ambient temperatures, noise and air pollution, and psychosocial health plus greater enjoyment and opportunity for exercise and enrichment of the human microbiome may underly these associations.

CONCLUSION

There is likely some protective effect of green space on stroke, with the benefits most convincingly shown for post-stroke outcomes. More research is recommended to confirm the protective association between green space exposure and reduced stroke risk.

Environmental factors and stroke: Risk and prevention

Stroke is a leading cause of death and adult disability globally. In addition to traditional risk factors, environmental risk factors have emerged over the recent past and are becoming increasingly important. The disproportionate rise of stroke incidence in low- and middle-income countries has been attributed, at least in part, to environmental factors. This narrative review provides details on the interplay between the environment and health generally and stroke specifically, covering topics including air pollution, atmospheric brown clouds, desert dust storms, giant wildfires, chemical contamination, biological aggressors, urbanization, and climate change. It also covers some beneficial environmental effects such as can be harnessed from the exposure to green spaces. It concludes with a summary of pragmatic actions that can be taken to help address some of these challenges at individual, community, and political advocacy levels.

A health data led approach for assessing potential health benefits of green and blue spaces: Lessons from an Irish case study

Research producing evidence-based information on the health benefits of green and blue spaces often has within its design, the potential for inherent or implicit bias which can unconsciously orient the outcomes of such studies towards preconceived hypothesis. Many studies are situated in proximity to specific or generic green and blue spaces (hence, constituting a green or blue space led approach), others are conducted due to availability of green and blue space data (hence, applying a green or blue space data led approach), while other studies are shaped by particular interests in the association of particular health conditions with presence of, or engagements with green or blue spaces (hence, adopting a health or health status led approach). In order to tackle this bias and develop a more objective research design for studying associations between human health outcomes and green and blue spaces, this paper discussed the features of a methodological framework suitable for that purpose after an initial, year-long, exploratory Irish study. The innovative approach explored by this study (i.e., the health-data led approach) first identifies sample sites with good and poor health outcomes from available health data (using data clustering techniques) before examining the potential role of the presence of, or engagement with green and blue spaces in creating such health outcomes. By doing so, we argue that some of the bias associated with the other three listed methods can be reduced and even eliminated. Finally, we infer that the principles and paradigm adopted by the health data led approach can be applicable and effective in analyzing other sustainability problems beyond associations between human health outcomes and green and blue spaces (e.g., health, energy, food, income, environment and climate inequality and justice etc.). The possibility of this is also discussed within this paper.

Impact of native-plants policy scenarios on premature mortality in Denver: A quantitative health impact assessment

BACKGROUND

Cities often use non-native plants such as turf grass to expand green space. Native plants, however, may require less water and maintenance and have co-benefits for local biodiversity, including pollinators. Previous studies estimating mortality averted by adding green space have not considered the provision of native plants as part of the greening policies.

AIM

We aim to estimate premature deaths that would be prevented by the implementation of native-plants policy scenarios in the City of Denver, Colorado, USA.

METHODS

After conducting interviews with local expert stakeholders, we designed four native-plants policy scenarios: (1) greening 30% of all city census-block groups to the greenness level of native plants, (2) adding 200-foot native-plants buffers around riparian areas, (3) constructing large water retention ponds landscaped with native plants, and (4) greening parking lots. We defined the normalized difference vegetation index (NDVI) corresponding to native plants by measuring the NDVI at locations with known native or highly diverse vegetation. Using a quantitative health-impact assessment approach, we estimated premature mortality averted under each scenario, comparing alternative NDVI with the baseline value.

RESULTS

In the most ambitious scenario, we estimated that 88 (95% uncertainty interval (UI): 20, 128) annual premature deaths would be prevented by greening 30% of the area of census block groups with native plants. We estimated that greening 30% of parking-lot surface with native plants would prevent 14 annual deaths (95% UI: 7, 18), adding the native buffers around riparian areas would prevent 13 annual deaths (95% UI: 2, 20), and adding the proposed stormwater retention ponds would prevent no annual deaths (95% UI: 0, 1).

CONCLUSION

Using native plants to increase green spaces has the potential to prevent premature deaths in the City of Denver, but results were sensitive to the definition of native plants and the policy scenario.

Global association of greenness exposure with risk of nervous system disease: A systematic review and meta-analysis

Nervous system disease (NSD) is a global health burden with increasing prevalence in the last 30 years. There is evidence that greenness can improve nervous system health through a variety of mechanisms; however, the evidence is inconsistent. In the present systematic review and meta-analysis, we examined the relationship between greenness exposure and NSD outcomes. Studies on the relationship between greenness and NSD health outcomes published till July 2022 were searched in PubMed, Cochrane, Embase, Scopus, and Web of Science. In addition, we searched the cited literature and updated our search on Jan 20, 2023, to identify any new studies. We included human epidemiological studies that assess the association of greenness exposure with the risk of NSD. Greenness exposure was measured using NDVI (the normalized difference vegetation index) and the outcome was the mortality or morbidity of NSD. The pooled relative risks (RRs) were estimated using a random effects model. Of 2059 identified studies, 15 studies were included in our quantitative evaluation, in which 11 studies found a significant inverse relationship between the risk of NSD mortality or incidence/prevalence and an increase in surrounding greenness. The pooled RRs for cerebrovascular diseases (CBVD), neurodegenerative diseases (ND), and stroke mortality were 0.98 (95 % CI: 0.97, 1.00), 0.98 (95 % CI: 0.98, 0.99), and 0.96 (95 % CI: 0.93, 1.00), respectively. The pooled RRs for PD incidence and stroke prevalence/incidence were 0.89 (95 % CI: 0.78, 1.02) and 0.98 (95 % CI: 0.97, 0.99), respectively. The confidence of evidence for ND mortality, stroke mortality, and stroke prevalence/incidence was downgraded to "low", while CBVD mortality and PD incidence were downgraded to "very low" due to inconsistency. We found no evidence of publication bias and the sensitivity analysis results of all subgroups are robust except for the stroke mortality subgroup. This is the first comprehensive meta-analysis of greenness exposure and NSD outcomes in which an inverse relationship was observed. It is necessary to conduct further research to ascertain the role greenness exposure plays in various NSDs and the management of greenness should be considered a public health strategy.

Associations of greenspace use and proximity with self-reported physical and mental health outcomes during the COVID-19 pandemic

Research has shown that the COVID-19 pandemic affected individual's mental and physical health. The aim of this study was to estimate associations between greenspace use and proximity with perceived mental and physical health during the COVID-19 pandemic. We surveyed metropolitan Philadelphia residents, October 20-December 1, 2020, about walking time to the nearest greenspace from their home, frequency of greenspace use in the past 30 days, change in frequency of greenspace use during the COVID-19 pandemic, and perceived physical and mental health outcomes. We ran unadjusted and adjusted log-binomial regression models to derive Risk Ratio (RR) and 95% Confidence Intervals (CI) estimates of associations of loneliness, physical and mental health outcomes with: (1) self-reported walking time to nearest greenspace; (2) reported greenspace use frequency; and (3) changes in greenspace use frequency. Of 485 survey participants, 244 (51.4%) reported feeling lonelier, 147 (31.37%) reported higher perceived stress, 261 (54.9%) reported worsened mental health, and 137 (28.7%) reported worsened physical health during vs. before the start of pandemic-restrictions in mid-March of 2020. After adjustment for gender, age, and change in financial status, RR estimates suggested modest protective associations between visiting greenspaces more frequently during vs. before the pandemic and worsened mental (RR: 0.84, 95% CI: 0.70-1.00), and physical health (RR 0.77, 95% CI: 0.56-1.10), and loneliness (RR: 0.91, 95% CI: 0.75-1.1) and perceived stress (RR 0.83, 95% CI: 0.61-1.13). Shorter walking distances to the nearest greenspace were associated with reduced risk of reporting worsened physical health and higher perceived stress; however, living shorter walking distances from greenspace were not associated with protection against worsened mental health or loneliness. These results suggest that active greenspace use may provide mental and physical health protection, particularly during a stressful public health crisis.

Increasing diversity in connectomics with the Chinese Human Connectome Project

Cultural differences and biological diversity play important roles in shaping human brain structure and function. To date, most large-scale multimodal neuroimaging datasets have been obtained primarily from people living in Western countries, omitting the crucial contrast with populations living in other regions. The Chinese Human Connectome Project (CHCP) aims to address these resource and knowledge gaps by acquiring imaging, genetic and behavioral data from a large sample of participants living in an Eastern culture. The CHCP collected multimodal neuroimaging data from healthy Chinese adults using a protocol comparable to that of the Human Connectome Project. Comparisons between the CHCP and Human Connectome Project revealed both commonalities and distinctions in brain structure, function and connectivity. The corresponding large-scale brain parcellations were highly reproducible across the two datasets, with the language processing task showing the largest differences. The CHCP dataset is publicly available in an effort to facilitate transcultural and cross-ethnic brain-mind studies.

Epigenetics: a new warrior against cardiovascular calcification, a forerunner in modern lifestyle diseases

Arterial and aortic valve calcifications are the most prevalent pathophysiological conditions among all the reported cases of cardiovascular calcifications. It increases with several risk factors like age, hypertension, external stimuli, mechanical forces, lipid deposition, malfunction of genes and signaling pathways, enhancement of naturally occurring calcium inhibitors, and many others. Modern-day lifestyle is affected by numerous environmental factors and harmful toxins that impair our health rather than providing benefits. Applying the combinatorial approach or targeting the exact mechanism could be a new strategy for drug designing or attenuating the severity of calcification. Most of the non-communicable diseases are life-threatening; thus, altering the phenotype and not the genotype may reveal the gateway for fighting with upcoming hurdles. Overall, this review summarizes the reason behind the generation of arterial and aortic valve calcification and its related signaling pathways and also the detrimental effects of calcification. In addition, the individual process of epigenetics and how the implementation of this process becomes a novel approach for diminishing the harmful effect of calcification are discussed. Noteworthy, as epigenetics is linked with genetics and environmental factors necessitates further clinical trials for complete and in-depth understanding and application of this strategy in a more specific and prudent manner.

The ‘Rippling’ Waves of Wellbeing: A Mixed Methods Evaluation of a Surf-Therapy Intervention on Patients with Acquired Brain Injury

Dominant psychological models of wellbeing neglect the role that nature connection and other key factors, such as positive health behaviours and behaviour change, play in determining wellbeing. The present mixed-methods evaluation explores the impact of ”Surf-Ability”, an adapted surf therapy intervention delivered in collaboration with a UK neurorehabilitation service, on individuals with acquired brain injury (ABI) as part of an effort to design interventions based on advances in wellbeing science. Following five surf-therapy sessions, within-subjects analysis (n= 15) revealed significant improvements on the Warwick–Edinburgh mental wellbeing scale (t (15) = −2.164, p = 0.048), as well as in anxiety and happiness as measured via a brief visual analogue. No significant changes occurred in the Hospital Anxiety and Depression Scale (HADS) or resting heart rate variability (HRV). A ripple effects mapping (REM) session at 6–10 months follow-up (n = 6) revealed that the physical and psychological experience of a nature-based challenge initiated a mindset shift in participants, which ultimately led to them adopting wellbeing-promoting long-term behaviour changes. These changes occurred at the scale of (1) individual wellbeing—increased mindfulness and physical activity; (2) collective wellbeing—improved relationships, community participation and contribution to organisations; and (3) planetary wellbeing—connection to nature. These findings align with the GENIAL theoretical framework, which defines wellbeing from a biopsychosocial ecological perspective across multiple levels of scale. The findings support the need for healthcare providers—including neurorehabilitation services—to enhance interventions for patients by incorporating novel factors that improve wellbeing, such as nature-connection.

Green areas and students' academic performance in the Federal District, Brazil: An assessment of three greenness metrics

Most of the epidemiological investigations looking at the health benefits of green spaces have measured the level of green areas by using only one approach, mainly the Normalized Difference Index - NDVI (a satellite-derived indicator). We hypothesized a difference in the association between health and green space depending on the metric used to measure green exposure. This study considers students' academic performance as a proxy of cognitive abilities (a health indicator). We estimated the relationship between green areas and students' academic performance in the Federal District (FD), Brazil, with three different greenness metrics: NDVI, distance to green spaces (m) - obtained from land use data, and quantity of green spaces (m²) - also from land use data. We assessed student-level academic performance data provided by the Department of the Education in the FD. The data includes students from the public schools in the FD for 256 schools (all the public schools in the FD) and 344,175 students (all the students enrolled in the public schools in the FD in 2017-2020).). For the first metric represented by the distance to green spaces, we estimated the straight-line distance between each school and the nearest green area. For NDVI and quantity of green spaces, we estimated the area of all green spaces within buffers of 500 m, 750 m, and 1 km around the schools. We applied a cross-sectional study design using mixed-effects regression models to analyze the association exposure to green areas around schools and student-level academic performance. Our results confirmed our hypothesis showing that the impact of green areas on students' performance varied significantly depending on the type of green metric. After adjustments for the covariates, we estimated that NDVI is positively associated with school-level academic performance, with an estimated coefficient of 0.91 (95%CI: 0.83; 0.99) for NDVI values at a school's centroid. Distance to green areas was negatively associated with academic performance [-2.09 × 10^-5 (95CI: 3.91 × 10^-5; -2.84 × 10^-6]. The quantity of green areas was estimated with mixed results (direction of the association), depending on the buffer size. Results from this paper suggest that epidemiological investigations must consider the different effects of greenness measures when looking at the association between green space and academic performance. More studies on residual confounding from this association with a different study design are needed to promote public health by making schools healthier.

Mortality risk associated with greenness, air pollution, and physical activity in a representative U.S. cohort

Several cohort studies suggest greenness is associated with decreased mortality risk. Potential confounding by or interactions between physical activity and air pollution remains unclear. This study evaluates associations of greenness, air pollution, and physical activity with mortality risk and investigates confounding and effect modification across these key risk factors. National Health Interview Survey (NHIS) data covering 1997-2014 were linked to the National Death Index to generate a cohort of 403,748 individuals with 39,528 deaths. Greenness, represented by census-tract Normalized Difference Vegetation Index (NDVI) for the seasonal period of May-October, was averaged over the years 2003-2016. Air pollution was estimated by census-tract level PM_2.5 concentrations from 1999 to 2015. Cox Proportional Hazard Models were used to estimate hazard ratios (HR) for differences in greenness, air pollution, and physical activity. Alternative models that evaluated potential confounding and stratified models that evaluated effect modification were examined. Mortality risks were associated with PM_2.5 (HR = 1.14, 95% CI: 1.09-1.19 per 10 μg/m³) and physical inactivity (1.49, 1.44-1.54 relative to sufficiently active), but not with greenness (1.01, 0.99-1.03 per IQR). The PM_2.5-mortality association was mitigated at high levels of greenness (1.05, 0.91-1.22). There was no strong evidence of confounding between air pollution, physical activity, and greenness. However, stratified analysis suggested effect modification for PM_2.5 and NDVI by physical activity. A significant protective greenness-mortality association was observed for only highly active individuals (0.91, 0.86-0.96). Also, relatively high PM_2.5-mortality HRs were observed for more physically active individuals (1.25, 1.12-1.40). PM_2.5 air pollution and physical inactivity are robustly associated with mortality risk. Greenness may be most beneficial and air pollution relatively harmful to highly active individuals. This analysis provides evidence that, in addition to not smoking, being physically active and living in a clean, green environment contributes to improved health and reduced risk of mortality.

Empirical dynamic modeling of the association between ambient PM2.5 and under-five mortality across 2851 counties in Mainland China, 1999-2012

BACKGROUND

Ambient fine particulate matter (PM_2.5) pollution has been associated with mortality from various diseases, however, its association with under-five mortality rate (U5MR) has remained largely unknown.

METHODS

Based on the U5MR data across 2851 counties in Mainland China from 1999 to 2012, we employed approximate Bayesian latent Gaussian models to assess the association between ambient PM_2.5 and U5MR at the county level for the whole nation and sub-regions. GDP growth rate, normalized difference vegetation index (NDVI), temperature, and night-time light were included as covariates using a smoothing function. We further implemented an empirical dynamic model (EDM) to explore the potential causal relationship between PM_2.5 and U5MR.

RESULTS

We observed a declining trend in U5MR in most counties throughout the study period. Spatial heterogeneity in U5MR was observed. Nationwide analysis suggested that each 10 µg/m³ increase in annual concentration of PM_2.5 was associated with an increase of 1.2 (95% CI: 1.0 - 1.3) per 1000 live births in U5MR. Regional analyses showed that the strongest positive association was located in the Northeastern part of China [1.8 (95% CI: 1.4 - 2.1)]. The EDM showed a significant causal association between PM_2.5 and U5MR, with an embedding dimension of 5 and 7, and nonlinear values θ of 4 and 6, respectively.

CONCLUSION

China exhibited a downward trend in U5MR from 1999 to 2012, with spatial heterogeneity observed across the country. Our analysis reveals a positive association between PM_2.5 and U5MR, which may support a causal relationship.

Associations Between Residential Greenspace, Socioeconomic Status, and Stroke: A Matched Case-Control Study

PURPOSE

Studies have shown increased residential greenspace is associated with improved outcome following stroke. This study sought to determine if residential greenspace is an independent stroke risk factor.

METHODS

A retrospective 1:4 matched case-control study involving 1174 stroke and 4696 control patients over a 3-year period from Milwaukee County, Wisconsin, was conducted. Greenspace was determined using normalized difference vegetation index (NDVI) for a 250-meter radius surrounding a subject's residence. The area deprivation index (ADI) for the census block tract of a subject's residence was obtained from the Neighborhood Atlas® (University of Wisconsin School of Medicine and Public Health). Relationship between greenspace, ADI, and stroke was determined using conditional logistic regression. Relationships among NDVI, state and national ADI, and proximity to public parks were determined using Spearman's rank-order correlation.

RESULTS

NDVI and stroke risk were inversely correlated (odds ratio [OR]: 0.33, 95% CI: 0.111-0.975; P=0.045), with 19% lowered odds of stroke for patients living in the highest greenspace quartile compared to the lowest quartile (OR: 0.81, 95% CI: 0.672-0.984; P=0.045). Patients living in the most deprived ADI quartile had 28% greater stroke risk than those living in the least deprived ADI quartile (OR: 1.28, 95% CI: 1.02-1.6; P=0.029). Non-Hispanic Black patients lived in residential areas with lower greenspace (P<0.001) and neighborhoods of greater state and national ADI (P<0.001 for both) than non-Hispanic White patients.

CONCLUSIONS

In Milwaukee County, living with greater surrounding greenspace or areas of lower deprivation is associated with lower odds of stroke. NDVI represents an independent risk factor for stroke, not simply a proxy for socioeconomic status.

Air pollution and surrounding greenness in relation to ischemic stroke: A population-based cohort study

BACKGROUND

Evidence for the association between environmental exposures and ischemic stroke (IS) is limited and inconsistent. We aimed to assess the relationship between exposure to air pollutants, residential surrounding greenness, and incident IS, and to identify population subgroups particularly sensitive to these exposures.

METHODS

We used data from administrative health registries of the public healthcare system in Catalonia, Spain to construct a cohort of individuals aged 18 years and older without a previous stroke diagnosis at 1st January 2016 (n = 3 521 274). We collected data on sociodemographic characteristics and cerebrovascular risk factors, and derived exposure at the participant's residence to ambient levels of fine particulate matter (PM_2.5), black carbon (BC), nitrogen dioxide (NO₂), and Normalized Difference Vegetation Index (NDVI) in a 300 m buffer as an indicator of greenness. The primary outcome was IS diagnosis at any point during the follow-up. We used Cox proportional hazards models to estimate associations between environmental exposures and incident IS and stratified analyses to investigate effect modification.

RESULTS

Between 1st January 2016 and 31st December 2017, 10 865 individuals were admitted to public hospitals with an IS diagnosis. Median exposure levels were: 17 µg/m³ PM_2.5, 35 µg/m³ NO₂, 2.28 µg/m³ BC and 0.27 NDVI. Individuals with higher residential exposure to air pollution were at greater risk of IS: HR 1·04 (95% CI:0·99-1·10) per 5 µg/m³ of PM_2.5; HR 1.05 (95% CI:1·00-1·10) per 1 µg/m³ of BC; HR 1·04 (95% CI:1·03-1·06) per 10 µg/m³ of NO₂. Conversely, individuals with higher residential surrounding green space, had lower risk of IS (HR 0·84; CI 95%:0·7-1.0). There was no evidence of effect modification by individual characteristics.

CONCLUSIONS

Higher incidence of IS was observed in relation to long-term exposures to air pollution, particularly NO₂, in a region that meets European health-based air quality standards. Residential surrounding greenness was associated with lower incidence of IS.

Socioeconomic Disparities in Hypertension by Levels of Green Space Availability: A Cross-Sectional Study in Philadelphia, PA

Green spaces have been proposed as equigenic factors, potentially mitigating health disparities. We used data from the 3887 participants residing in Philadelphia who participated in the Public Health Management Corporation’s Southeastern Pennsylvania Household Health Survey in 2014–2015 to assess whether socioeconomic disparities in hypertension are modified by availability of neighborhood-level green spaces. Socioeconomic status (SES) was measured using individual-level education and neighborhood-level median household income. Green space availability was measured using surrounding percent tree canopy cover, mean normalized difference vegetation index (NDVI), and proximity to nearest park. Using logistic regression models adjusted for age, sex, and race/ethnicity, we found that adults with higher educational attainment had significantly lower levels of hypertension (OR = 0.63, 0.57, and 0.36 for high school, some college, and college graduates, respectively, as compared to those with less than high school education), and this pattern was similar for median household income (higher prevalence in lower income areas). We found no significant interaction between education and percent tree canopy cover (p = 0.83), meaning that educational disparities in hypertension were similar across all levels of green space availability. These results held when using mean NDVI or distance to nearest park as availability measures, or when considering neighborhood-level median household income as the socioeconomic measure, although the specific patterns and significance of interactions varied by exposure and modifier. While socioeconomic disparities in hypertension are strong for adults residing in Philadelphia, green spaces did not seem to modify them.

Community planning for a "healthy built environment" via a human-environment nexus? A multifactorial assessment of environmental characteristics and age-specific stroke mortality in Hong Kong

With the prevalence of stroke rising due to both aging societies and more people getting strokes at a younger age, a comprehensive investigation into the relationship between urban characteristics and age-specific stroke mortality for the development of a healthy built environment is necessary. Specifically, assessment of various dimensions of urban characteristics (e.g. short-term environmental change, long-term environmental conditions) is needed for healthy built environment designs and protocols. A multifactorial assessment was conducted to evaluate associations between environmental and sociodemographic characteristics with age-stroke mortality in Hong Kong. We found that short-term (and temporally varying) daily PM₁₀, older age and being female were more strongly associated with all types of stroke deaths compared to all-cause deaths in general. Colder days, being employed and being married were more strongly associated with hemorrhagic stroke deaths in general. Long-term (and spatially varying) regional-level air pollution were more strongly associated with non-hemorrhagic stroke deaths in general. These associations varied by age. Employment (manual workers) and low education were risk factors for stroke mortality at younger ages (age <65). Greenness and open space did not have a significant association with stroke mortality. Since a significant connection was expected, this leads to questions about the health-inducing efficacy of Hong Kong's compact open spaces (natural greenery being limited to steep slopes, and extensive impervious surfaces on public open spaces). In conclusion, urban plans and designs for stroke mortality prevention should implement age-specific health care to neighborhoods with particular population segments.

Urban forest biodiversity and cardiovascular disease: Potential health benefits from California's street trees

Enhanced immune functioning in response to biodiversity may explain potential health benefits from exposure to green space. Using unique data on urban forest biodiversity at the zip code level for California measured from 2014 to 2019 we test whether greater diversity of street trees is associated with reduced death from cardiovascular disease. We find that urban forests with greater biodiversity measured via the Shannon Index at the genus level are associated with a lower mortality rate for heart disease and stroke. Our estimates imply that increasing the Shannon Index by one standard deviation (0.64) is associated with a decrease in the mortality rate of 21.4 per 100,000 individuals for heart disease or 13% and 7.7 per 100,000 individuals for stroke or 16%. Our estimates remain robust across several sensitivity checks. A policy simulation for tree planting in Los Angeles based on our estimates suggests that if these relationships were causal, investment in planting for a more biodiverse set of street trees would be a cost-effective way to reduce mortality related to cardiovascular disease in urban areas.

Do we know enough to quantify the impact of urban green spaces on mortality? An analysis of the current knowledge

OBJECTIVES

The addition of green spaces (GS) in cities is perceived as an efficient solution to combat climate change and biodiversity loss while also improving human health. Quantitative health impact assessment (QHIA) is a powerful tool to assess the health benefits of GS and support policy-making decisions. In France, a preliminary analysis of the literature led to the decision of developing guidance for QHIA applied to GS and mortality. This paper focuses on the choice of exposure-response functions (ERF) for those QHIA.

STUDY DESIGN

Literature review and analysis of the key steps of QHIA.

METHODS

Articles providing ERF for all-cause, cardiovascular and respiratory mortality in relation to GS were identified through a literature review and ranked based on a quality score. ERF from the articles with the highest scores was pooled in meta-analyses.

RESULTS

In total, 13 ERF were selected for all-cause mortality, 10 for cardiovascular mortality and 5 for respiratory mortality. Meta-risk for a 0.1 increase in the normalised differential vegetation index were, 0.96 (95% confidence interval [CI] 0.94; 0.97), 0.98 (95% CI 0.96; 0.99) and 0.97 (95% CI 0.92; 1.02) for all-cause, cardiovascular and respiratory mortality, respectively.

CONCLUSIONS

While current knowledge makes it possible to use QHIA on GS and mortality, interdisciplinary research is still needed to clarify the shape of the relationship and its temporality and to assess exposure in a meaningful way for decision-making.

Estimating multiple greenspace exposure types and their associations with neighbourhood premature mortality: A socioecological study

BACKGROUND

Greenspace exposures are often measured using single exposure metrics, which can lead to conflicting results. Existing methodologies are limited in their ability to estimate greenspace exposure comprehensively. We demonstrate new methods for estimating single and combined greenspace exposure metrics, representing multiple exposure types that combine impacts at various scales. We also investigate the association between those greenspace exposure types and premature mortality.

METHODS

We used geospatial data and spatial analytics to model and map greenspace availability, accessibility and eye-level visibility exposure metrics. These were harmonised and standardised to create a novel composite greenspace exposure index (CGEI). Using these metrics, we investigated associations between greenspace exposures and years of potential life lost (YPLL) for 1673 neighbourhoods applying spatial autoregressive models. We also investigated the variations in these associations in conjunction with levels of socioeconomic deprivation based on the index of multiple deprivations.

RESULTS

Our new CGEI metric provides the opportunity to estimate spatially explicit total greenspace exposure. We found that a 1-unit increase in neighbourhood CGEI was associated with approximately a 10-year reduction in YPLL. Meaning a 0.1 increment or 10% increase in the CGEI is associated with an approximately one year lower premature mortality value. A single 1-unit increase in greenspace availability was associated with a YPLL reduction of 9.8 years, whereas greenness visibility related to a reduction of 6.14 years. We found no significant association between greenspace accessibility and YPLL. Our results further identified divergent trends in the relations between greenspace exposure types (e.g. availability vs. accessibility) and levels of socioeconomic deprivation (e.g. least vs. most).

CONCLUSION

Our methods and metrics provide a novel approach to the assessment of multiple greenspace exposure types, and can be linked to the broader exposome framework. Our results showed that a higher composite greenspace exposure is associated with lower premature mortality.

Resilience and Equity in a Time of Crises: Investing in Public Urban Greenspace Is Now More Essential Than Ever in the US and Beyond

The intersecting negative effects of structural racism, COVID-19, climate change, and chronic diseases disproportionately affect racial and ethnic minorities in the US and around the world. Urban populations of color are concentrated in historically redlined, segregated, disinvested, and marginalized neighborhoods with inadequate quality housing and limited access to resources, including quality greenspaces designed to support natural ecosystems and healthy outdoor activities while mitigating urban environmental challenges such as air pollution, heat island effects, combined sewer overflows and poor water quality. Disinvested urban environments thus contribute to health inequity via physical and social environmental exposures, resulting in disparities across numerous health outcomes, including COVID-19 and chronic diseases such as cancer and cardiovascular diseases (CVD). In this paper, we build off an existing conceptual framework and propose another conceptual framework for the role of greenspace in contributing to resilience and health equity in the US and beyond. We argue that strategic investments in public greenspaces in urban neighborhoods impacted by long term economic disinvestment are critically needed to adapt and build resilience in communities of color, with urgency due to immediate health threats of climate change, COVID-19, and endemic disparities in chronic diseases. We suggest that equity-focused investments in public urban greenspaces are needed to reduce social inequalities, expand economic opportunities with diversity in workforce initiatives, build resilient urban ecosystems, and improve health equity. We recommend key strategies and considerations to guide this investment, drawing upon a robust compilation of scientific literature along with decades of community-based work, using strategic partnerships from multiple efforts in Milwaukee Wisconsin as examples of success.

The influence of urban, socio-economic, and eco-environmental aspects on COVID-19 cases, deaths and mortality: A multi-city case in the Atlantic Forest, Brazil

Urban, socio-economic and eco-environmental influences on people's health are widely studied and well-known. Their relation to COVID-19, however, is still a novel research topic. Thus, we investigated if COVID-19 parameters are higher in cities with higher urbanization, worst socio-economic conditions, and less vegetation cover, considering 3,052 municipalities in the Atlantic Forest, Brazil. Brazil is the second country most affected by COVID-19, and the Atlantic Forest is its most urbanized, populous, and deforested region. Indexes were created through multivariate principal components analysis using secondary official data: population, demographic density, absolute built area, and relative built area as urbanization parameters; average per capita income, relative people vulnerable to poverty, illiteracy rate of the population aged 18 or over, and human development index (HDI) as socio-economic parameters; and absolute and relative vegetation cover, absolute and relative forest cover as eco-environmental parameters. These indexes were correlated with absolute and relative confirmed COVID-19 cases, absolute and relative confirmed deaths, and mortality rate via Spearman's and Kendall's coefficients. Strong correlations (>0.50) were found between COVID-19 and urbanization. Socio-economic and eco-environmental aspects, although weaker predictors of COVID-19, presented meaningful relations with the health parameters. This study contributes to the evidence regarding COVID-19 incidence in the Brazilian population.

Particulate air pollution and survival after stroke in older adults: A retrospective cohort study in Korea

Although many studies have evaluated the effects of ambient particulate matter with diameters of less than 2.5 μm (PM_2.5) on stroke mortality in the general population, little is known about the mortality effects of PM_2.5 in post-stroke populations. Therefore, a retrospective cohort was constructed using information from the health insurance database to evaluate whether exposure to PM_2.5 is associated with increased mortality in aged stroke survivors residing in seven Korean metropolitan cities. A total of 45,513 older adults (≥65 years) who visited emergency rooms due to stroke and who were discharged alive between 2008 and 2016 were followed up. By using district-level modeled PM_2.5 concentrations and a time-varying Cox proportional hazard model, associations between 1-month and 2-month moving average PM_2.5 exposures and mortality in stroke survivors were evaluated. The annual average concentration of PM_2.5 was 27.9 μg/m³ in the seven metropolitan cities, and 14,880 subjects died during the follow-up period. A 10 μg/m³ increase in the 1-month and 2-month moving average PM_2.5 exposures was associated with mortality hazard ratios of 1.07 (95% confidence interval: 1.05, 1.09) and 1.06 (95% confidence interval: 1.03, 1.08), respectively. The effects of PM_2.5 were similar across types of stroke (ischemic and hemorrhagic), age groups (65-74, 75-84, and ≥85), and income groups (low and high) but were greater in women than in men. This study highlights the adverse health effects of ambient PM_2.5 in post-stroke populations. Active avoidance behaviors against PM_2.5 are recommended for aged stroke survivors.

Moving Beyond Disciplinary Silos Towards a Transdisciplinary Model of Wellbeing: An Invited Review

The construct of wellbeing has been criticised as a neoliberal construction of western individualism that ignores wider systemic issues such as inequality and anthropogenic climate change. Accordingly, there have been increasing calls for a broader conceptualisation of wellbeing. Here we impose an interpretative framework on previously published literature and theory, and present a theoretical framework that brings into focus the multifaceted determinants of wellbeing and their interactions across multiple domains and levels of scale. We define wellbeing as positive psychological experience, promoted by connections to self, community and environment, supported by healthy vagal function, all of which are impacted by socio-contextual factors that lie beyond the control of the individual. By emphasising the factors within and beyond the control of the individual and highlighting how vagal function both affects and are impacted by key domains, the biopsychosocial underpinnings of wellbeing are explicitly linked to a broader context that is consistent with, yet complementary to, multi-levelled ecological systems theory. Reflecting on the reciprocal relationships between multiple domains, levels of scale and related social contextual factors known to impact on wellbeing, our GENIAL framework may provide a foundation for a transdisciplinary science of wellbeing that has the potential to promote the wellbeing of individuals while also playing a key role in tackling major societal challenges.

Associations of air pollution and greenness with mortality in Greece: An ecological study

BACKGROUND

Epidemiological studies have documented the adverse effects of long-term exposure to fine particulate matter (PM_2.5) on health, while there has been less research on the effects of nitrogen dioxide (NO₂), black carbon (BC) and especially ozone (O₃). Furthermore, there is limited evidence for the synergistic effects of exposure to pollutants and greenness. We investigated the association of long-term exposure to air pollution and greenness with natural-cause, cardiovascular and respiratory mortality in Greece using an ecological study design.

METHODS

Mortality and socioeconomic data were obtained from 1035 municipal units from the 2011 census data. Annual average PM_2.5, NO₂, BC and O₃ concentrations for 2010 were derived from 100 × 100 m surfaces predicted by hybrid LUR models. The normalized difference vegetation index was used to assess greenness. We applied Poisson regression models on standardized mortality rates adjusted for socioeconomic indicators and lung cancer rates, accounting for spatial autocorrelation. The analysis was conducted initially for the whole country and then separately for urban and rural areas. We assessed interactions between pollutants and greenness and applied two-exposure models.

RESULTS

An interquartile range (IQR) increase in PM_2.5, NO₂ and BC was associated with increases in natural-cause mortality (Relative Risk (RR) 1.09, 95% confidence interval (CI): 1.08, 1.11; RR 1.03 (95% CI: 1.03, 1.04) and RR 1.02 (95% CI: 1.02, 1.03), respectively), while PM_2.5 and NO₂ were also associated with cause-specific mortality. Greenness was associated with lower natural-cause (RR 0.95, 95% CI: 0.94, 0.96 per IQR) and cause-specific mortality. For all outcomes we estimated a protective association with O₃ (natural-cause mortality RR 0.79, 95% CI: 0.76, 0.82 per IQR). All associations were stronger in urban areas. We estimated negative statistically significant interactions between air pollution and greenness for respiratory morality and positive ones for cardiovascular mortality. Estimates were mostly robust to co-exposure adjustment.

CONCLUSIONS

Our findings support associations of air pollution and greenness with mortality, both in urban and rural areas of Greece. Further research is needed to elaborate on the synergies in cause-specific mortality. Our results on the interactions between pollutants and greenness may imply differential biological mechanisms for cause-specific mortality and warrant further investigation.

Associations between Nature Exposure and Health: A Review of the Evidence

There is extensive empirical literature on the association between exposure to nature and health. In this narrative review, we discuss the strength of evidence from recent (i.e., the last decade) experimental and observational studies on nature exposure and health, highlighting research on children and youth where possible. We found evidence for associations between nature exposure and improved cognitive function, brain activity, blood pressure, mental health, physical activity, and sleep. Results from experimental studies provide evidence of protective effects of exposure to natural environments on mental health outcomes and cognitive function. Cross-sectional observational studies provide evidence of positive associations between nature exposure and increased levels of physical activity and decreased risk of cardiovascular disease, and longitudinal observational studies are beginning to assess long-term effects of nature exposure on depression, anxiety, cognitive function, and chronic disease. Limitations of current knowledge include inconsistent measures of exposure to nature, the impacts of the type and quality of green space, and health effects of duration and frequency of exposure. Future directions include incorporation of more rigorous study designs, investigation of the underlying mechanisms of the association between green space and health, advancement of exposure assessment, and evaluation of sensitive periods in the early life-course.

Socioeconomic status as an effect modifier of the association between built environment and mortality in elderly Hong Kong Chinese: A latent profile analysis

BACKGROUND

Previous studies have focused on associations between individual built environment (BE) characteristics and mortality, and found the BE-mortality associations differed by socioeconomic status (SES). Different individual BE characteristics may have different impacts on health and thus could interact. Combinations of BE characteristics may be a better approach to explore the BE-mortality associations.

OBJECTIVES

This study aimed to investigate the associations of BE pattern with mortality in a prospective cohort of elderly Hong Kong Chinese (Mr. OS and Ms. OS Study), and assess whether the BE-mortality association differed by SES.

METHODS

Between 2001 and 2003, 3944 participants aged 65-98 years at baseline were included in the present analysis. BE characteristics were assessed via Geographic Information System. Data on all-cause and cause-specific mortality were obtained from the Hong Kong Government Death Registry. Latent profile analysis was used to derive BE class, and the Cox proportional hazards model was used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs).

RESULTS

Three BE classes were identified. During a total of 53276 person-years of follow-up, 1632 deaths were observed. There were no significant associations of BE class with all-cause and cause-specific mortality. However, we found the associations of BE class with all-cause mortality were modified by SES. In comparison with Class 3 (characterized by greater green space), HRs (95%CIs) were 0.72 (0.54, 0.97) for Class 1 (characterized by greater commercial land use) and 0.77 (0.64, 0.94) for Class 2 (characterized by greater residential land use) among low-SES participants. The associations were stronger among high-SES participants, with 0.55 (0.33, 0.89) for Class 1 and 0.68 (0.48, 0.97) for Class 2. In contrast, Class 2 (HR 1.18, 95%CI 1.01-1.39) had a higher mortality risk compared with Class 3 among middle-SES participants.

CONCLUSIONS

Our findings provide new evidence on the role of SES as an effect modifier of BE pattern and mortality. BE pattern has a varied effect on mortality risk for different SES groups.

Association of neighborhood greenness exposure with cardiovascular diseases and biomarkers

AIM

Living in areas with neighborhood greenness may be associated with the incidence of cardiovascular diseases (CVDs). However, little evidence in this regard has emerged from developing countries. In the present study, we examined neighborhood greenness associated with CVDs and the lipid accumulation product (LAP) and pulse pressure (PP) in China.

METHODS

We undertook our analysis using a community cross-sectional survey conducted in Longzihu District of Bengbu from July to August 2015. We measured triglyceride levels, waist circumference, and blood pressure. To assess exposure to neighborhood greenness, we used the average normalized difference vegetation index (NDVI) at 1,000-, 1,500-, and 2,000-m buffers in the participant community. We employed generalized mixed models to determine the association among neighborhood greenness, CVDs, LAP, and PP. We conducted stratified analysis by age, gender, income, and education. We assessed the potential mediating effects of road proximity and physical activity on greenness and CVDs, PP, and LAP.

RESULTS

The highest tertiles of NDVI_1500-m were steadily and significantly associated with lower odds of CVDs prevalence: the adjusted OR of such prevalence was 0.612 (95% CI, 0.462-0.811); higher NDVI was significantly associated with lower PP levels. The NDVI was strongly associated with CVDs prevalence among participants who were male and had high income. Ambient road proximity significantly mediated 9.7% of the estimated association between greenness and PP, there was no evidence of mediation effects for physical activity.

CONCLUSIONS

Higher neighborhood greenness could have a beneficial effect on CVDs and biomarkers. There were higher associations between residential greenness and CVDs among male and higher-income individuals; road proximity partially mediated the observed association between greenness and PP.

Green Space and Health Equity: A Systematic Review on the Potential of Green Space to Reduce Health Disparities

Disadvantaged groups worldwide, such as low-income and racially/ethnically minoritized people, experience worse health outcomes than more privileged groups, including wealthier and white people. Such health disparities are a major public health issue in several countries around the world. In this systematic review, we examine whether green space shows stronger associations with physical health for disadvantaged groups than for privileged groups. We hypothesize that disadvantaged groups have stronger protective effects from green space because of their greater dependency on proximate green space, as they tend to lack access to other health-promoting resources. We use the preferred reporting items for systematic reviews and meta-analyses (PRISMA) method and search five databases (CINAHL, Cochrane, PubMed, Scopus, and Web of Science) to look for articles that examine whether socioeconomic status (SES) or race/ethnicity modify the green space-health associations. Based on this search, we identify 90 articles meeting our inclusion criteria. We find lower-SES people show more beneficial effects than affluent people, particularly when concerning public green spaces/parks rather than green land covers/greenness. Studies in Europe show stronger protective effects for lower-SES people versus higher-SES people than do studies in North America. We find no notable differences in the protective effects of green space between racial/ethnic groups. Collectively, these results suggest green space might be a tool to advance health equity and provide ways forward for urban planners, parks managers, and public health professionals to address health disparities.

Residing in urban areas with higher green space is associated with lower mortality risk: A census-based cohort study with ten years of follow-up

BACKGROUND

Epidemiological studies suggest that residing close to green space reduce mortality rates. We investigated the relationship between long-term exposure to residential green space and non-accidental and cardio-respiratory mortality.

METHODS

We linked the Belgian 2001 census to population and mortality register follow-up data (2001-2011) among adults aged 30 years and older residing in the five largest urban areas in Belgium (n = 2,185,170 and mean follow-up time 9.4 years). Residential addresses were available at baseline. Exposure to green space was defined as 1) surrounding greenness (2006) [normalized difference vegetation index (NDVI) and modified soil-adjusted vegetation index (MSAVI2)] within buffers of 300 m, 500 m, and 1000 m; 2) surrounding green space (2006) [Urban Atlas (UA) and CORINE Land Cover (CLC)] within buffers of 300 m, 500 m, and 1000 m; and 3) perceived neighborhood green space (2001). Cox proportional hazards models with age as the underlying time scale were used to probe into cause-specific mortality (non-accidental, respiratory, COPD, cardiovascular, ischemic heart disease (IHD), and cerebrovascular). Models were adjusted for several sociodemographic variables (age, sex, marital status, country of birth, education level, employment status, and area mean income). We further adjusted our main models for annual mean (2010) values of ambient air pollution (PM_2.5, PM₁₀, NO₂ and BC, one at a time), and we additionally explored potential mediation with the aforementioned pollutants.

RESULTS

Higher degrees of residential green space were associated with lower rates of non-accidental and respiratory mortality. In fully adjusted models, hazard ratios (HR) per interquartile range (IQR) increase in NDVI 500 m buffer (IQR: 0.24) and UA 500 m buffer (IQR: 0.31) were 0.97 (95%CI 0.96-0.98) and 0.99 (95%CI 0.98-0.99) for non-accidental mortality, and 0.95 (95%CI 0.93-0.98) and 0.97 (95%CI 0.96-0.99) for respiratory mortality. For perceived neighborhood green space, HRs were 0.93 (95%CI 0.92-0.94) and 0.94 (95%CI 0.91-0.98) for non-accidental and respiratory mortality, respectively. The observed lower mortality risks associated with residential exposure to green space were largely independent from exposure to ambient air pollutants.

CONCLUSION

We observed evidence for lower mortality risk in associations with long-term residential exposure to green space in most but not all studied causes of death in a large representative cohort for the five largest urban areas in Belgium. These findings support the importance of the availability of residential green space in urban areas.

Identification and Estimation of Causal Effects Using a Negative-Control Exposure in Time-Series Studies With Applications to Environmental Epidemiology

The initial aim of environmental epidemiology is to estimate the causal effects of environmental exposures on health outcomes. However, due to lack of enough covariates in most environmental data sets, current methods without enough adjustments for confounders inevitably lead to residual confounding. We propose a negative-control exposure based on a time-series studies (NCE-TS) model to effectively eliminate unobserved confounders using an after-outcome exposure as a negative-control exposure. We show that the causal effect is identifiable and can be estimated by the NCE-TS for continuous and categorical outcomes. Simulation studies indicate unbiased estimation by the NCE-TS model. The potential of NCE-TS is illustrated by 2 challenging applications: We found that living in areas with higher levels of surrounding greenness over 6 months was associated with less risk of stroke-specific mortality, based on the Shandong Ecological Health Cohort during January 1, 2010, to December 31, 2018. In addition, we found that the widely established negative association between temperature and cancer risks was actually caused by numbers of unobserved confounders, according to the Global Open Database from 2003-2012. The proposed NCE-TS model is implemented in an R package (R Foundation for Statistical Computing, Vienna, Austria) called NCETS, freely available on GitHub.

The Effect of Surrounding Greenness on Type 2 Diabetes Mellitus: A Nationwide Population-Based Cohort in Taiwan

This study determines whether surrounding greenness is associated with the incidence of type 2 diabetes Mellitus (T2DM) in Taiwan. A retrospective cohort study determines the relationship between surrounding greenness and the incidence of T2DM during the study period of 2001–2012 using data from the National Health Insurance Research Database. The satellite-derived normalized difference vegetation index (NDVI) from the global MODIS database in the NASA Earth Observing System is used to assess greenness. Cox proportional hazard models are used to determine the relationship between exposure to surrounding greenness and the incidence of T2DM, with adjustment for potential confounders. A total of 429,504 subjects, including 40,479 subjects who developed T2DM, were identified during the study period. There is an inverse relationship between exposure to surrounding greenness and the incidence of T2DM after adjustment for individual-level covariates, comorbidities, and the region-level covariates (adjusted HR = 0.81, 95% CI: 0.79–0.82). For the general population of Taiwan, greater exposure to surrounding greenness is associated with a lower incidence of T2DM.

Increasing Green Infrastructure in Cities: Impact on Ambient Temperature, Air Quality and Heat-Related Mortality and Morbidity

Urban vegetation provides undeniable benefits to urban climate, health, thermal comfort and environmental quality of cities and represents one of the most considered urban heat mitigation measures. Despite the plethora of available scientific information, very little is known about the holistic and global impact of a potential increase of urban green infrastructure (GI) on urban climate, environmental quality and health, and their synergies and trade-offs. There is a need to evaluate globally the extent to which additional GI provides benefits and quantify the problems arising from the deployment of additional greenery in cities which are usually overlooked or neglected. The present paper has reviewed and analysed 55 fully evaluated scenarios and case studies investigating the impact of additional GI on urban temperature, air pollution and health for 39 cities. Statistically significant correlations between the percentage increase of the urban GI and the peak daily and night ambient temperatures are obtained. The average maximum peak daily and night-time temperature drop may not exceed 1.8 and 2.3 °C respectively, even for a maximum GI fraction. In parallel, a statistically significant correlation between the peak daily temperature decrease caused by higher GI fractions and heat-related mortality is found. When the peak daily temperature drops by 0.1 °C, then the percentage of heat-related mortality decreases on average by 3.0% The impact of additional urban GI on the concentration of urban pollutants is analysed, and the main parameters contributing to decrease or increase of the pollutants’ concentration are presented.

Effect of nature exposure on perceived and physiologic stress: A systematic review

OBJECTIVE

The purpose of this systematic review is to evaluate the effect nature exposure has on stress as measured by physiologic markers and self-report.

DESIGN

Researchers searched PubMed and JSTOR. Randomized control trials and cross-sectional studies were included if they met the following criteria: 1) included a clinical cohort and controls, and the intervention was nature exposure, either real or simulated; (2) utilized measurements of sympathetic activity or perceived stress; (3) study population consisted of greater than thirty male and female volunteers. Twelve studies were included for data extraction and review.

SETTING

Researchers conducted this review at University of South Florida Morsani College of Medicine.

MAIN OUTCOME MEASURES

Researchers measured perceived stress through the Perceived Stress Scale (PSS) and Depression, Anxiety, and Stress Scale (DASS). Physiologic stress was measured by salivary cortisol, blood pressure (BP), subgenual prefrontal cortex (sgPFC) activation on functional magnetic resonance imaging (fMRI), skin conductance level (SCL), heart rate variability (HRV), muscle tension, heart period, pulse transit time, amygdala and pregenual anterior cingulate cortex (pACC) activation on fMRI, respiratory sinus arrhythmia (RSA), and pre-ejection period (PEP).

RESULTS

This review found an inverse relationship between nature exposure and various physiologic markers of stress in all 7 studies measuring physiologic stress. Perceived stress was also affected by higher exposure to nature as indicated by lower self-reports on the PSS and DASS in 5 out of 6 studies measuring perceived stress.

CONCLUSIONS

Nature exposure has been widely shown to have a positive effect in reducing stress, both perceived and physiologic.

Association Between Residential Greenness, Cardiometabolic Disorders, and Cardiovascular Disease Among Adults in China

IMPORTANCE

Living in areas with more vegetation (referred to as residential greenness) may be associated with cardiovascular disease (CVD), but little data are available from low- and middle-income countries. In addition, it remains unclear whether the presence of cardiometabolic disorders modifies or mediates the association between residential greenness and CVD.

OBJECTIVE

To evaluate the associations between residential greenness, cardiometabolic disorders, and CVD prevalence among adults in China.

DESIGN, SETTING, AND PARTICIPANTS

This analysis was performed as part of the 33 Communities Chinese Health Study, a large population-based cross-sectional study that was conducted in 33 communities (ranging from 0.25-0.64 km2) in 3 cities within the Liaoning province of northeastern China between April 1 and December 31, 2009. Participants included adults aged 18 to 74 years who had resided in the study area for 5 years or more. Greenness levels surrounding each participant's residential community were assessed using the normalized difference vegetation index and the soil-adjusted vegetation index from 2010. Lifetime CVD status (including myocardial infarction, heart failure, coronary heart disease, cerebral thrombosis, cerebral hemorrhage, cerebral embolism, and subarachnoid hemorrhage) was defined as a self-report of a physician diagnosis of CVD at the time of the survey. Cardiometabolic disorders, including hypertension, diabetes, dyslipidemia, and overweight or obese status, were measured and defined clinically. Generalized linear mixed models were used to evaluate the association between residential greenness levels and CVD prevalence. A 3-way decomposition method was used to explore whether the presence of cardiometabolic disorders mediated or modified the association between residential greenness and CVD. Data were analyzed from October 10 to May 30, 2020.

MAIN OUTCOMES AND MEASURES

Lifetime CVD status, the presence of cardiometabolic disorders, and residential greenness level.

RESULTS

Among 24 845 participants, the mean (SD) age was 45.6 (13.3) years, and 12 661 participants (51.0%) were men. A total of 1006 participants (4.1%) reported having a diagnosis of CVD. An interquartile range (1-IQR) increase in the normalized difference vegetation index within 500 m of a community was associated with a 27% lower likelihood (odds ratio [OR], 0.73; 95% CI, 0.65-0.83; P < .001) of CVD prevalence, and an IQR increase in the soil-adjusted vegetation index within 500 m of a community was associated with a 26% lower likelihood (OR, 0.74; 95% CI, 0.66-0.84; P < .001) of CVD prevalence. The presence of cardiometabolic disorders was found to mediate the association between residential greenness and CVD, with mediation effects of 4.5% for hypertension, 4.1% for type 2 diabetes, 3.1% for overweight or obese status, 12.7% for hypercholesterolemia, 8.7% for hypertriglyceridemia, and 11.1% for high low-density lipoprotein cholesterol levels.

CONCLUSIONS AND RELEVANCE

In this cross-sectional study, higher residential greenness levels were associated with lower CVD prevalence, and this association may be partially mediated by the presence of cardiometabolic disorders. Further studies, preferably longitudinal, are warranted to confirm these findings.

Planning for Supportive Green Spaces in the Winter City of China: Linking Exercise of Elderly Residents and Exercise Prescription for Cardiovascular Health

The elderly population have a high incidence of cardiovascular disease and are the main users of green spaces, such as city parks. Creating supportive green spaces for exercise for the elderly is of great significance to promote their cardiovascular health. The winter cities have a severely cold climate and high incidence of cardiovascular disease, while the elderly, especially those with cardiovascular disease, face more challenges when participating in exercise in the green spaces. In the context of the winter cities, the kinds of exercise the elderly participate in are more conducive to their cardiovascular health, and determining the factors of the green spaces that are supportive for exercise for cardiovascular health in the winter are of particular interest. Taking Harbin, a typical winter city in China, as an example, this study aims to identify the exercise characteristics of elderly residents in the green spaces in winter, to link them with the principles and contents of exercise prescription for cardiovascular health, to identify the deficient factors of the green spaces in supporting exercise for cardiovascular health, and to put forward optimization design implications. Mixed qualitative methods including interviews, a questionnaire, and field observation were used to identify special behavioral characteristics and spatial factors involving winter exercise in the green spaces among the elderly. The results showed that: (1) about 42.4% of the participants had a gap with the principles of exercise prescription for cardiovascular health. Their exercise items were generally consistent with the principle of low-intensity exercise, but some of them had the problems regarding early exercise time and insufficient exercise duration and frequency. (2) Insufficient supportive factors of the green spaces mainly included facilities allocation, comfort, safety, accessibility, and air quality. Facilities allocation involved walking paths, rehabilitation facilities, auxiliary facilities, and guidance facilities; comfort involved sunlight conditions of the exercise areas; safety involved slippery roads and sites with ice and snow and medical accidents; accessibility involved the proximity, the safety of connecting roads, and the movement of the elderly; air quality involved the planting of evergreen trees. Accordingly, the design implications were given in order to bridge the supportive gap of the green spaces for exercise for cardiovascular health in the elderly population.

Residential Greenness and Cardiovascular Disease Incidence, Readmission, and Mortality

BACKGROUND

Living in greener areas of cities was linked to increased physical activity levels, improved mental well-being, and lowered harmful environmental exposures, all of which may affect human health. However, whether living in greener areas may be associated with lower risk of cardiovascular disease incidence, progression, and premature mortality is unclear.

OBJECTIVES

We conducted a cohort study to examine the associations between residential green spaces and the incidence of acute myocardial infarction (AMI) and heart failure (HF), post-AMI and HF hospital readmissions, and mortality.

METHODS

We simultaneously followed four large population-based cohorts in Ontario, Canada, including the entire adult population, adults free of AMI and HF, and survivors of AMI or HF from 2000 to 2014. We estimated residential exposure to green spaces using satellite-derived observations and ascertained health outcomes using validated disease registries. We estimated the associations using spatial random-effects Cox proportional hazards models. We conducted various sensitivity analyses, including further adjusting for property values and performing exploratory mediation analysis.

RESULTS

Each interquartile range increase in residential greenness was associated with a 7% [95% confidence interval (CI): 4%, 9%] decrease in incident AMI and a 6% (95% CI: 4%, 7%) decrease in incident HF. Residential greenness was linked to a ∼10% decrease in cardiovascular mortality in both adults free of AMI and HF and the entire adult population. These associations remained consistent in sensitivity analyses and were accentuated among younger adults. Additionally, we estimated that the decreases in AMI and HF incidence associated with residential greenness explained ∼53% of the protective association between residential greenness and cardiovascular mortality. Conversely, residential greenness was not associated with any delay in readmission or mortality among AMI and HF patients.

CONCLUSIONS

Living in urban areas with more green spaces was associated with improved cardiovascular health in people free of AMI and HF but not among individuals who have already developed these conditions. https://doi.org/10.1289/EHP6161.

Urban green space and the risks of dementia and stroke

INTRODUCTION

It is unknown whether urban green space is associated with reduced risk of major neurological conditions, especially dementia and stroke.

METHODS

Retrospective, population-based cohorts were created for each study outcome, including 1.7 and 4.3 million adults in Ontario, Canada for dementia and stroke, respectively. Residential green space was quantified using the satellite-derived Normalized Difference Vegetation Index. Incidence was ascertained using health administrative data with validated algorithms. Mixed-effects Cox models were used to estimate hazard ratios per interquartile range increase in green space exposure.

RESULTS

Between 2001 and 2013, 219,013 individuals were diagnosed with dementia and 89,958 had a stroke. The hazard ratio per interquartile range increase in green space was 0.97 (95% CI: 0.96-0.98) for dementia and 0.96 (0.95-0.98) for stroke. Estimates remained generally consistent in sensitivity analyses.

DISCUSSION

Increased exposure to urban green space was associated with reduced incidence of dementia and stroke. To our knowledge, this is the first population-based cohort study to assess these relationships.

The contribution of residential greenness to mortality among men with prostate cancer: a registry-based cohort study of Black and White men

Black men with prostate cancer (CaP) experience excess mortality compared with White men. Residential greenness, a health promoting contextual factor, could explain racial disparities in mortality among men with CaP.

Health impact assessment of Philadelphia's 2025 tree canopy cover goals

BACKGROUND

Cities across the world are undertaking ambitious projects to expand tree canopy by increasing the number of trees planted throughout public and private spaces. In epidemiological studies, greenspaces in urban environments have been associated with physical and mental health benefits for city dwellers. Greenworks Philadelphia is a plan to increase tree cover across Philadelphia (PA, USA) by the year 2025. We aimed to assess whether an increase in tree canopy or greenspace in Philadelphia could decrease mortality.

METHODS

We did a greenspace health impact assessment to estimate the annual premature mortality burden for adult residents associated with projected changes in tree canopy cover in Philadelphia between 2014 and 2025. Using up-to-date exposure-response functions, we calculated the number of preventable annual premature deaths city-wide, and for areas of lower versus higher socioeconomic status, for each of three tree canopy scenarios: low, moderate and ambitious. The ambitious scenario reflected the city's goal of 30% tree canopy cover in each of the city's neighbourhoods; and low and moderate scenarios were based on the varying levels of plantable space across neighbourhoods.

FINDINGS

We estimated that 403 (95% interval 298-618) premature deaths overall, including 244 (180-373) premature deaths in areas of lower socioeconomic status, could be prevented annually in Philadelphia if the city were able to meet its goal of increasing tree canopy cover to 30%.

INTERPRETATION

Bringing all of Philadelphia, and particularly its poorer neighbourhoods, up to the 30% goal of tree canopy cover is not without challenge. Nevertheless, policies are warranted that value urban greening efforts as health-promoting and cost-saving measures.

FUNDING

Spanish Ministry of Science, Innovation and Universities, and Generalitat de Catalunya.

CHIMGEN: a Chinese imaging genetics cohort to enhance cross-ethnic and cross-geographic brain research

The Chinese Imaging Genetics (CHIMGEN) study establishes the largest Chinese neuroimaging genetics cohort and aims to identify genetic and environmental factors and their interactions that are associated with neuroimaging and behavioral phenotypes. This study prospectively collected genomic, neuroimaging, environmental, and behavioral data from more than 7000 healthy Chinese Han participants aged 18-30 years. As a pioneer of large-sample neuroimaging genetics cohorts of non-Caucasian populations, this cohort can provide new insights into ethnic differences in genetic-neuroimaging associations by being compared with Caucasian cohorts. In addition to micro-environmental measurements, this study also collects hundreds of quantitative macro-environmental measurements from remote sensing and national survey databases based on the locations of each participant from birth to present, which will facilitate discoveries of new environmental factors associated with neuroimaging phenotypes. With lifespan environmental measurements, this study can also provide insights on the macro-environmental exposures that affect the human brain as well as their timing and mechanisms of action.

Interaction between residential greenness and air pollution mortality: analysis of the Chinese Longitudinal Healthy Longevity Survey

BACKGROUND

Both air pollution and green space have been shown to affect health. We aimed to assess whether greenness protects against air pollution-related mortality.

METHODS

We used data from the 2008 wave of the Chinese Longitudinal Healthy Longevity Survey. We calculated contemporaneous normalised difference vegetation index (NDVI) in the 500 m radius around each participant's residence. Fine particulate matter (PM_2·5) concentration was calculated using 3-year average concentrations in 1 km × 1 km grid resolution. We used Cox proportional hazards models to estimate the effects of NDVI, PM_2·5, and their interaction on all-cause mortality, adjusted for a range of covariates.

FINDINGS

The cohort contained 12 873 participants, totalling 47 884 person-years. There were 7426 deaths between 2008 and 2014. The mean contemporaneous NDVI was 0·42 (SD 0·21), and the mean 3-year average PM_2·5 was 49·63 μg/m³ (13·72). In the fully adjusted model, the mortality hazard ratio for each 0·1-unit decrease in contemporaneous NDVI was 1·08 (95% CI 1·03-1·13), each 10 μg/m³ increase in PM_2·5 was 1·13 (1·09-1·18), and the interaction term was 1·01 (1·00-1·02) with a p value of 0·027. We observed non-linear associations in our stratified analyses: people living in urban areas were more likely to benefit from greenness, and people living in rural areas were more likely to be harmed by air pollution.

INTERPRETATION

Our study showed some indication of a synergistic effect of greenness and air pollution, suggesting that green space planning and air pollution control can jointly improve public health.

FUNDING

Bill & Melinda Gates Foundation, National Institutes of Health, National Key R&D Program of China, National Natural Science Foundation of China.