Greenspace Metrics Research Articles

Satellite-Based and Street-View Green Space and Adiposity in US Children

Green space may be associated with obesity outcomes in children by promoting physical activity and reducing stress. However, previous studies have mostly used a single measure of green space and body mass index (BMI) as the sole indicator of adiposity. To examine associations of the satellite-based normalized difference vegetation index (NDVI) and street-view imagery-based green space metrics with comprehensive adiposity measures in children. The Project Viva cohort study observed participants from mid-childhood (mean [SD] age, 8.0 [0.8] years) and early adolescence (mean [SD] age, 13.3 [1.0] years) through late adolescence (mean [SD] age, 17.8 [0.7] years) between January 1, 2007, and December 31, 2021. This analysis included children with data on green space and adiposity measures. Data were analyzed from January 1 to June 30, 2024. Green space metrics (ie, percentage of trees, grass, and other green space) using street-view imagery and deep learning algorithms along with the NDVI were linked with participants' home addresses during mid-childhood and early adolescence. Body mass index (calculated as weight in kilograms divided by height in meters squared) and waist circumference z scores were calculated from anthropometric measurements during early and late adolescence. The total fat mass index (FMI; calculated as fat mass in kilograms divided by height in meters squared) and trunk FMI were obtained using dual-energy x-ray absorptiometry. Separate linear regression models adjusted for a child's age, sex, individual and neighborhood socioeconomic status, and population density estimated prospective associations of the NDVI and street-view green space (in mid-childhood or early adolescence) with 4 adiposity measures (in early or late adolescence). The sample included 843 children (mean [SD] age at mid-childhood, 7.9 [0.8] years; 423 girls [50.2%]) at baseline. After adjustment for confounders, a higher NDVI (per 1-SD increase) within 270 m in early adolescence was associated with lower z scores for BMI (-0.16 [95% CI, -0.27 to -0.04]) and waist circumference (-0.13 [95% CI, -0.23 to -0.03]), as well as a lower total FMI (-0.62 [95% CI, -1.02 to -0.23]) and trunk FMI (-0.33 [95% CI, -0.55 to -0.12]) in late adolescence. Higher percentages of street-view other green space (flowers, plants, and fields), but not street-view trees and grass, within 500 m in early adolescence were associated with lower BMI z scores (-0.09 [95% CI, -0.18 to -0.01) in late adolescence. The NDVI and street-view green space exposure at mid-childhood were not associated with adiposity measures in early adolescence. This cohort study of US children suggests that higher levels of satellite-based NDVI greenness and percentages of street-level green space components (flowers, plants, and fields) were associated with lower adiposity. The findings support the exploration of increasing residential green space levels and adding specific green space components as an urban planning and public health intervention strategy to combat the prevalence of childhood obesity in the US.

A Systematic Review of the Associations Between Biodiversity and Children's Mental Health and Wellbeing.

There is a growing interest in how exposure to biodiversity influences mental health and wellbeing; however, few studies have focused on children. The aim of this review was to identify studies that used components of biodiversity and children's health outcomes to assess if there were any themes that could be used to inform urban design and understand the mechanisms behind associations. We used a PROSPERO registered protocol to identify eligible studies following pre-defined inclusion criteria. After searching five databases, 25 studies were included in the review. From these articles we extracted data on the biodiversity exposure and mental health and wellbeing outcomes. Five categories of biodiversity exposure were identified, including species diversity (n = 1; 4%), functional diversity (n = 6; 26%), ecological community (n = 9; 36%), green space metrics (n = 4; 16%), and high-level classifications (n = 6; 24%). Children's health and wellbeing were tabulated into seven categories: play (n = 10; 40%), wellbeing (n = 6; 24%), mental health and cognitive functioning (n = 5; 20%), attention deficit hyperactivity disorder (ADHD)-related behaviours (n = 4; 16%), preferences for nature (n = 3; 12%), academic achievement (n = 2; 8%), and restoration (n = 2; 8%). The high heterogeneity of biodiversity and health measures reduced our ability to identify relationships across studies and formally test for an exposure-dose response. Future research that uses standardised and transferable biodiversity measurements at multiple scales, has stronger reporting rigour, greater consideration of potential modifiers, and increased representation of studies from the Majority World are essential for building a stronger evidence base to deliver child-centred biodiverse landscapes.

Assessing greenspace and cardiovascular health through deep-learning analysis of street-view imagery in a cohort of US children

BackgroundAccurately capturing individuals' experiences with greenspace at ground-level can provide valuable insights into their impact on children's health. However, most previous research has relied on coarse satellite-based measurements. MethodsWe utilized CVH and residential address data from Project Viva, a US-based pre-birth cohort, tracking participants from mid-childhood to late adolescence (2007-21). A deep learning segmentation algorithm was applied to street-view images across the US to estimate % street-view trees, grass, and other greenspace (flowers, field, and plants). Exposure estimates were derived by linking street-view greenspace metrics to 500m of participants' residences during mid-childhood, early and late adolescence. CVH scores (range 0–100; higher indicate better CVH) were calculated using the American Heart Association's Life's Essential 8 algorithm at these three time points, incorporating four biomedical components (body weight, blood lipids, blood glucose, blood pressure) and four behavioral components (diet, physical activity, nicotine exposure, sleep). Linear regression models were used to examine cross-sectional and cumulative associations between street-view greenspace metrics and CVH scores. Generalized estimating equations models were used to examine associations between street-view greenspace metrics and changes in CVH scores across three timepoints. All models were adjusted for individual and neighborhood-level confounders. ResultsAdjusting for confounders, a one-SD increase in street-view trees within 500m of residence was cross-sectionally associated with a 1.92-point (95%CI: 0.50, 3.35) higher CVH score in late adolescence, but not mid-childhood or early adolescence. Longitudinally, street-view greenspace metrics at baseline (either mid-childhood or early adolescence) were not associated with changes in CVH scores at the same and all subsequent time points. Cumulative street-view greenspace metrics across the three time points were also not associated with CVH scores in late adolescence. Conclusion and RelevanceIn this US cohort of children, we observed few evidence of associations between street-level greenspace children's CVH, though the impact may vary with children's growth stage.

Place-Based Differences in the Association Between Greenspace and Suicide-Related Outcomes Among Young People

PurposeThis study investigated place-based differences in the association between greenspace and suicide-related outcomes (SROs) among young people, guided by the following two objectives: (1) Contextualize place-based differences in the association between greenspace and SRO prevalence among young people at the community level in five different urbanities (urban, suburban, micropolitan, small towns, and rural/isolated communities) and (2) identify which greenspace metrics (quantity, quality, or accessibility) are most protective for SROs at the community level. MethodsPublicly available greenspace datasets were used to derive greenspace quantity, quality, and accessibility metrics. SRO emergency department visits for young people were identified from 2016–2019 in North Carolina, USA. Generalized linear models investigated the association between greenspace metrics and community-level drivers of SRO prevalence. Shapely additive explanations confirmed the most important greenspace variables in accurately predicting community-level SRO prevalence. ResultsThe prevalence of SROs was highest in communities with the least amount of public greenspace; this association was most pronounced in suburban communities, with SROs 27% higher in suburban communities with low quantities of greenspace (PRRUrban: 1.11, confidence interval [CI]: 1.08–1.13; PRRSuburban: 1.27, CI: 1.10–1.46; PRRSmallTowns: 1.21, CI: 1.05–1.39), and in communities with the worst greenspace accessibility (i.e., furthest distance to nearest greenspace) (PRRUrban: 1.07, CI: 1.04–1.10; PRRRural&Isolated: 1.95, CI: 1.54–2.49). DiscussionOur analysis provides place-based, community-specific findings to guide targeted greenspace interventions aimed at addressing the rising prevalence of SROs among young people. Our findings suggest that greenspace quantity interventions may be most effective in urban, suburban, and small-town communities, and greenspace accessibility interventions may be most useful in urban and rural/isolated communities.

Fine particulate matter-sudden death association modified by ventricular hypertrophy and inflammation: a case-crossover study.

Sudden death accounts for approximately 10% of deaths among working-age adults and is associated with poor air quality. Objectives: To identify high-risk groups and potential modifiers and mediators of risk, we explored previously established associations between fine particulate matter (PM2.5) and sudden death stratified by potential risk factors. Sudden death victims in Wake County, NC, from 1 March 2013 to 28 February 2015 were identified by screening Emergency Medical Systems reports and adjudicated (n = 399). Daily PM2.5 concentrations for Wake County from the Air Quality Data Mart were linked to event and control periods. Potential modifiers included greenspace metrics, clinical conditions, left ventricular hypertrophy (LVH), and neutrophil-to-lymphocyte ratio (NLR). Using a case-crossover design, conditional logistic regression estimated the OR (95%CI) for sudden death for a 5 μg/m3 increase in PM2.5 with a 1-day lag, adjusted for temperature and humidity, across risk factor strata. Individuals having LVH or an NLR above 2.5 had PM2.5 associations of greater magnitude than those without [with LVH OR: 1.90 (1.04, 3.50); NLR > 2.5: 1.25 (0.89, 1.76)]. PM2.5 was generally less impactful for individuals living in areas with higher levels of greenspace. LVH and inflammation may be the final step in the causal pathway whereby poor air quality and traditional risk factors trigger arrhythmia or myocardial ischemia and sudden death. The combination of statistical evidence with clinical knowledge can inform medical providers of underlying risks for their patients generally, while our findings here may help guide interventions to mitigate the incidence of sudden death.

Assessing life expectancy disparities in Chicago with a deep dive into green space

BackgroundFew studies have examined the association between green space and life expectancy, and only one study has looked at that data for small areas in the United States. These studies have found a positive association between green space and life expectancy. This study investigates the association between green space and small-area life expectancy in Chicago, a city in the United States with distinct environmental and socioeconomic characteristics and the largest U.S. life expectancy gap between neighborhoods. MethodsWe conducted a spatial analysis using the green space metrics of normalized difference vegetation index (NDVI), park access, and tree canopy. Additionally, we included 18 lifestyle, environmental, and social covariates. Diagnostic analytics included multiple linear regression, Moran I test for spatial dependence, and principal component analysis with CAR Gaussian model. We performed a simulation to predict life expectancy gain if NDVI was brought to median levels. ResultsOur study revealed that after adjusting for covariates and spatial dependence (Moran I test p = 0.012) with a CAR Gaussian model, NDVI (credible interval = 0.292-0.894) demonstrated significance at a 5 % level, while tree canopy (credible interval = -0.404-0.109) and park access (credible interval = -0.258-0.161) did not. Excluding non-significant variables (tree canopy and park access) from the CAR Gaussian model, the median effect of NDVI on life expectancy was 0.491 (95 % credible interval: 0.24–0.718). Projecting this effect to tracts below the median NDVI predicted a gain of 476,000 years of life expectancy for Chicago residents. ConclusionThis study provides evidence that green space and LE are positively correlated, suggesting the potential to increase green space to address current LE gaps. Future research should investigate the mechanisms by which green space correlates to lifespan.

Pathways linking greenspace to behavioural problems in Polish children

BackgroundPrevious cross-sectional studies have found a beneficial relationship between greenspace and children's behaviour. Nevertheless, evidence on the mechanisms underlying this association remains scant. We examined whether the availability of greenspace was related to fewer behavioural problems in Polish children and investigated potential mechanisms. MethodsData were obtained from the case-control NeuroSmog study, in which children with and without attention deficit hyperactivity disorder (ADHD) were tested from October 2020 to September 2022. The analytic sample comprised 679 children aged 10–13 years. Parents reported internalizing, externalizing, and total behavioural problems using the Child Behaviour Check List (CBCL), as well as information about the presence of a domestic garden and potential mediators: greenspace perception, neighbourhood social cohesion, and physical activity. Tree and grass covers were extracted in 500 m and 1 km buffers around lifelong residences. Structural equation modelling (SEM) was used to examine the psychosocial pathways linking the greenspace metrics to behavioural problems. ResultsGreenspace was only indirectly related to fewer behavioural problems. Specifically, tree cover was related to greater levels of physical activity which, in turn, was related to fewer internalizing and total behavioural problems. Tree cover and presence of garden were related to greenspace perception which, in turn, was associated with higher neighbourhood social cohesion which, in turn, was linked to fewer behavioural problems. The patterns of associations in children without ADHD were very similar to those in the full sample except that the associations from garden to greenspace perception and from physical activity to total behavioural problems were no longer significant. The only association persisted among girls was from neighbourhood social cohesion to behavioural problems and among boys were from tree cover to physical activity and tree cover and garden to greenspace perception. ConclusionTrees and garden, but not grass, are linked to fewer behavioural problems through greenspace perception, neighbourhood social cohesion, and physical activity in Polish children.

Associations of neighborhood greenspace, and active living environments with autism spectrum disorders: A matched case-control study in Ontario, Canada

BackgroundIncreasing evidence links early life residential exposure to natural urban environmental attributes and positive health outcomes in children. However, few studies have focused on their protective effects on the risk of autism spectrum disorder (ASD). The aim of this study was to investigate the associations of neighborhood greenspace, and active living environments during pregnancy with ASD in young children (≤6 years). MethodsWe conducted a population-based matched case-control study of singleton term births in Ontario, Canada for 2012–2016. The ASD and environmental data was generated using the Ontario Autism Spectrum Profile, the Better Outcomes Registry & Network Ontario, and Canadian Urban Environmental Health Research Consortium. We employed conditional logistic regressions to estimate the odds ratio (OR) between ASD and environmental factors characterizing selected greenspace metrics and neighborhoods conducive to active living (i.e., green view index (GVI), normalized difference vegetation index (NDVI), tree canopy, park proximity and active living environments index (ALE)). ResultsWe linked 8643 mother-child pairs, including 1554 cases (18%). NDVI (OR 1.034, 0.944–1.024, per Inter Quartile Range [IQR] = 0.08), GVI (OR 1.025, 95% CI 0.953–1.087, per IQR = 9.45%), tree canopy (OR 0.992, 95% CI 0.903–1.089, per IQR = 6.24%) and the different categories of ALE were not associated with ASD in adjusted models for air pollution. In contrast, living closer to a park was protective (OR 0.888, 0.833–0.948, per 0.06 increase in park proximity index), when adjusted for air pollution. ConclusionsThis study reported mixed findings showing both null and beneficial effects of green spaces and active living environments on ASD. Further investigations are warranted to elucidate the role of exposure to greenspaces and active living environments on the development of ASD.

Abstract MP76: Street View Greenspace Exposures and Cardiovascular Health Among Children - Evidence From Project Viva

Introduction: Research on greenspace and cardiovascular health (CVH) in children is limited, and most previous studies rely on coarse satellite-based measurements of greenspace, which do not capture exposure as individuals experience it. Street View imagery (SVI) enables measurement of greenspace from a ground-level perspective and captures specific elements of greenspace that may be most relevant to health. This study aimed to examine associations of SVI-based greenspace with CVH in children in Project Viva, an eastern Massachusetts-based cohort. Methods: Using data from 1,163 children, we applied deep learning segmentation algorithms to SVI from 2007-2010 to derive metrics of greenspace (%of trees, or grass) within a 500m radius of participants’ residential addresses obtained during mid-childhood (mean age 7.9y). At mid-childhood and early adolescence (mean age 13.2y), we calculated CVH scores (range 0-100 units; higher scores represent better CVH) using the American Heart Association’s Life’s Essential 8 algorithm, based on 4 biomedical measures (body mass index, blood lipids, blood glucose, and blood pressure) and 4 behavioral measures (heart healthy levels of diet, physical activity, avoidance of nicotine, and sleep). Using linear regression, we examined associations of mid-childhood SVI-based greenspace metrics with mid-childhood (cross-sectional) and early adolescence (longitudinal) CVH scores, adjusting for child’s sex, race and ethnicity, and age at outcome, as well as an index score of socioeconomic status comprising individual and neighborhood metrics. Results: Among the 1163 participants, 65% were non-Hispanic White and 49% were female. The mean (SD) LE8 score was 83.3 (8.0) in mid-childhood and 81.7 (8.9) in early adolescence. In the unadjusted models, a higher %trees and grass per SD, as measured by SVI within children’s residence in mid-childhood, was associated with a higher overall CVH score (β 1.63 [95%CI: 0.93, 2.33] for trees; β 1.10 [95%CI: 0.36, 1.83] for grass). In longitudinal analyses, the results were similar (β 1.69 [95%CI: 0.87, 2.52] for trees; β 0.82 [95%CI: -0.01, 1.64] for grass). In fully-adjusted analyses, the cross-sectional and longitudinal results for %trees and grass were attenuated and not statistically significant. However, when CVH scores were disaggregated by behavioral and biomedical sub-scores, %trees was positively associated with behavioral sub-scores in cross-sectional fully-adjusted analyses at mid-childhood (β 0.89 [95%CI: 0.32, 1.46]). Conclusion: Among participants in Project Viva, SVI-based metrics of greenspace exposure in mid-childhood were cross-sectionally associated with behavioral factors promoting higher CVH. Greenspace may hold promise for improving children’s CVH through the behavioral pathway and should be considered in future health-promotion efforts.

Advancing Understanding on Greenspace and Mental Health in Young People.

Mental distress among young people has increased in recent years. Research suggests that greenspace may benefit mental health. The objective of this exploratory study is to further understanding of place-based differences (i.e., urbanity) in the greenspace-mental health association. We leverage publicly available greenspace data sets to operationalize greenspace quantity, quality, and accessibility metrics at the community-level. Emergency department visits for young people (ages 24 and under) were coded for: anxiety, depression, mood disorders, mental and behavioral disorders, and substance use disorders. Generalized linear models investigated the association between greenspace metrics and community-level mental health burden; results are reported as prevalence rate ratios (PRR). Urban and suburban communities with the lowest quantities of greenspace had the highest prevalence of poor mental health outcomes, particularly for mood disorders in urban areas (PRR: 1.19, 95% CI: 1.16-1.21), and substance use disorders in suburban areas (PRR: 1.35, 95% CI: 1.28-1.43). In urban, micropolitan, and rural/isolated areas further distance to greenspace was associated with a higher prevalence of poor mental health outcomes; this association was most pronounced for substance use disorders (PRRUrban: 1.31, 95% CI: 1.29-1.32; PRRMicropolitan: 1.47, 95% CI: 1.43-1.51; PRRRural 2.38: 95% CI: 2.19-2.58). In small towns and rural/isolated communities, poor mental health outcomes were more prevalent in communities with the worst greenspace quality; this association was most pronounced for mental and behavioral disorders in small towns (PRR: 1.29, 95% CI: 1.24-1.35), and for anxiety disorders in rural/isolated communities (PRR: 1.61, 95% CI: 1.43-1.82). The association between greenspace metrics and mental health outcomes among young people is place-based with variations across the rural-urban continuum.

Associations between urban greenspace and depressive symptoms in Mexico's cities using different greenspace metrics

BackgroundGreenspace has been shown to be positively associated with mental wellbeing, but studies from the global South have been scarce. We advance the understanding of the relationship between greenspace and depressive symptoms by using multiple clearly defined metrics describing neighborhood greenness and urban parks in an understudied region with rapid urban growth. MethodsWe linked individual-level health survey data for urban residents in Mexico (n = 17,258 respondents in 84 cities) with measures of greenspace such as satellite-derived normalized difference vegetation index (NDVI), percent green area, urban parks characteristics, and kernel-density-derived continuous greenspace indicator. We estimated the odds ratios of experiencing depressive symptoms associated with greenspace at residential neighborhoods adjusted for individual and area-level characteristics. ResultsAmong the various measures of greenspace investigated, the amount of greenness measured by neighborhood NDVI was associated with smaller odds of depressive symptoms. An increase by one standard deviation in the median of annual maximum NDVI at neighborhood level is associated with 8.7 % (Odds Ratio [OR] = 0.913, 95 % CI 0.853–0.977) lower odds of experiencing depressive symptoms, adjusted for individual and area-level characteristics. We find some evidence that, when neighborhood-level greenness is accounted for, the broader availability of greenspace outside of the neighborhood may be associated with smaller odds of depressive symptoms. We found no statistically significant associations for the measures describing % greenspace in a neighborhood and urban parks, and the results were not sensitive to seasonal changes in greenness. Neighborhood-level particulate matter (PM2.5) may lessen the benefits of greenspace for depressive symptoms. ConclusionsHigher neighborhood-level greenness as measured by NDVI is associated with smaller odds of depressive symptoms in Mexico's cities, whereas many other metrics are not. The influence of the choice of greenspace metrics on the subsequent associations highlights the importance of clear operational definitions of greenspace and the need to consider multiple complementary greenspace metrics in greenspace-health research.

Greenspace and Land Cover Diversity During Pregnancy in a Rural Region, and Associations With Birth Outcomes.

Beneficial effects on health outcomes have been observed from exposure to spaces with substantial green vegetation ("greenspace"). This includes studies of greenspace exposure on birth outcomes; however, these have been conducted largely in urban regions. We characterized residential exposure to greenspace and land cover diversity during pregnancy in rural northern New England, USA, investigating whether variation in greenspace or diversity related to newborn outcomes. Five landscape variables (greenspace land cover, land cover diversity, impervious surface area, tree canopy cover, and the Normalized Difference Vegetation Index) were aggregated within six circular zones of radii from 100 to 3,000m around residential addresses, and distance to conservation land was measured, providing a total of 31 greenspace and diversity metrics. Four birth outcomes along with potentially confounding variables were obtained from 1,440 participants in the New Hampshire Birth Cohort Study. Higher greenspace land cover up to 3,000m was associated with larger newborn head circumference, while impervious surface area (non-greenspace) had the opposite association. Further, birth length was positively associated with land cover diversity. These findings support beneficial health impacts of greenspace exposure observed in urban regions for certain health outcomes, such as newborn head circumference and length but not others such as birthweight and gestational age. Further our results indicate that larger radius buffer zones may be needed to characterize the rural landscape. Vegetation indices may not be interchangeable with other greenspace metrics such as land cover and impervious surface area in rural landscapes.

Association between urban greenspace, tree canopy cover and intentional deaths: An exploratory geospatial analysis

Greenspaces can provide restorative experiences, offer opportunities for outdoor recreation, and reduce mental fatigue; all of which may improve community health and safety. Yet few studies have examined the neighborhood-level benefits of greenspace in reducing violent deaths. This study explored the association between three distinct greenspace metrics: public greenspace quantity, public greenspace accessibility, neighborhood tree canopy cover, and intentional deaths (i.e., homicides and suicides). Generalized linear models and spatial error models investigated the association between greenspace, tree canopy and intentional deaths in three geographically distinct cities in North Carolina, USA. Results revealed that increased neighborhood greenspace accessibility and tree canopy cover were associated with reduced intentional deaths in all three urban areas. Neighborhood greenspace accessibility was the most protective factor across all study areas. The association between neighborhood greenspace accessibility and intentional deaths was more significant for non-firearm deaths as compared to firearm deaths, indicating that weapon type may be an important consideration for neighborhood greenspace interventions. Compared to predominantly White neighborhoods, predominantly Black neighborhoods had higher rates of homicide in Asheville and Durham and higher rates of suicide in Charlotte. Future policy and research should focus on improving equitable access to existing and future greenspaces, especially in primarily Black neighborhoods.

The association of green space, tree canopy and parks with life expectancy in neighborhoods of Los Angeles

Substantial evidence suggests that access to urban green spaces and parks is associated with positive health outcomes, including decreased mortality. Few existing studies have investigated the association between green spaces and life expectancy (LE), and none have used small-area data in the U.S. Here we used the recently released U.S. Small-Area Life Expectancy Estimates Project data to quantify the relationship between LE and green space in Los Angeles County, a large diverse region with inequities in park access. We developed a model to quantify the association between green space and LE at the census tract level. We evaluated three green space metrics: normalized difference vegetation index (NDVI, 0.6-meter scale), percent tree canopy cover, and accessible park acres. We statistically adjusted for 15 other determinants of LE. We also developed conditional autoregressive models to account for spatial dependence. Tree canopy and NDVI were both significantly associated with higher LE. For an interquartile range (IQR) increase in each metric respectively, the spatial models demonstrated a 0.24 to 0.33-year increase in LE. Tree canopy and NDVI also modified the effect of park acreage on LE. ln areas with tree canopy levels below the county median, an IQR increase in park acreage was associated with an increase of 0.12 years. Although on an individual level these effects were modest, we predicted 155,300 years of LE gains across the population in LA County if all areas below median tree canopy were brought to the county median of park acres. If tree canopy or NDVI were brought to median levels, between 570,300 and 908,800 years of LE could be gained. The majority of potential gains are in areas with predominantly Hispanic/Latinx and Black populations. These findings suggest that equitable access to green spaces could result in substantial population health benefits.

Associations between Google Street View-derived urban greenspace metrics and air pollution measured using a distributed sensor network

With urbanisation occurring at an unprecedented rate worldwide, there is an urgent need to address air pollution-related health risks in urban areas. Although urban greenspace presents an opportunity to balance those risks, little research investigates the association between urban greenspace and air pollution. As such, in this first-of-a-kind study, we examined associations between street-level urban greenspace and air pollution metrics at multiple spatial scales using largescale Information Communications Technology (ICT) derived environmental datasets in an urban area. Urban greenspace was modelled using Google Street View images and computer vision methods in high spatial resolution and termed the Green View Index (GVI). Another greenspace metric, the Normalised Difference Vegetation Index, was quantified using Landsat satellite imagery and computational algorithms. Particulate matter (PM) air pollution of varying size fractions (PM2.5, PM10, PM1) was measured using a distributed network of air pollution sensors. Higher levels of urban greenspace were associated with decreases in PM air pollution. For example, an interquartile range (5.44) increase in GVI, within a buffer radius of 2000m around air pollution sensors, was significantly (p<0.01) associated with a 1.94μg/m3 [95% Confidence Interval: -3.03, -0.85] decrease in PM2.5. The findings will inform the planning and design of smart, sustainable and healthy future cities.

Investigation on sociodemographic and health inequity of greenspace using different greenspace indicators in 3 US urban communities

BACKGROUND AND AIM Study results are inconclusive regarding how greenspace exposure differs by sociodemographic status potentially due to lack of consideration of varying dimensions of greenspace. We investigated the inequity of greenspace and its health effects by sociodemographic status comparing various greenspace metrics. METHODS We used five metrics: vegetation levels measured by Enhanced Vegetation Index (EVI), percent greenspace, percent tree cover, percent tree cover along walkable roads, and percent people living &amp;#x3c;500m of a park entrance (park accessibility). We used data for 2008–2013 in Census block groups in 3 US regions: New Haven, Connecticut; Baltimore, Maryland; Durham, North Carolina. We examined associations between each greenspace metric and indicators of income, education, linguistic isolation, race/ethnicity, and age. Logistic regressions examined associations between these greenspace metrics and age-standardized mortality controlling for sociodemographic indicators. RESULTS The region with the highest greenspace differed across metrics. Average percent greenspace was highest in Durham and lowest in Baltimore. Average percent people living &amp;#x3c;500m of a park entrance and percent tree cover along walkable roads were highest in New Haven. An interquartile range (64.7%) increase in people of color was associated with a 6.2% (95%CI: 3.1–9.3) increase in park accessibility, whereas it was associated with 0.03–7.3% decreases in other greenspace metrics. A 15.5% increase in the lower-education population was associated with a 2.1% increase (95%CI: -0.3%–4.6%) in park accessibility but decreases with other greenspace metrics (0.02–5.0%). The odds ratios of having an all-cause standardized mortality rate &amp;#x2265;75th percentile were inversely associated with all greenspace metrics except for park accessibility (OR=1.40, 95% CI: 0.52–3.75). CONCLUSIONS Environmental justice concerns and health benefits of greenspace can differ by form of greenspace and socioeconomic status within communities. Comparisons of greenspace between different greenspace metrics should be incorporated in decision-making. KEYWORDS Environmental justice, greenspace, health inequity.

Comparing greenspace metrics and buffer methods in Metro Vancouver, Canada: Implications for environmental health research

BACKGROUND &amp;#x26; AIM: Access and exposure to greenspace has been shown to promote mental and physical health; however, not all studies have found these benefits, with some studies reporting no association and others reporting associations with adverse health outcomes. It has been suggested that the use of diverse greenspace metrics, the varied quality of these metrics, and the specific methods used to quantify exposure or access, may contribute to these inconsistent findings. This project sought to compare the results of using different metrics in Metro Vancouver, Canada. METHODS: Greenspace metrics were calculated from the centroid of each 6-digit postal code. Average buffer normalized differences vegetation index (NDVI), green landcover, tree canopy cover, and park count were calculated using circular and network buffers, at both 400m and 1000m. Pearson’s correlation coefficients were calculated to compare the results for each metric and method. RESULTS: The number of parks was only weakly positively correlated with each of the other three greenspace metrics for 1000m circular buffers (NDVI r = 0.12; green land cover r = 0.07; tree canopy r = 0.14, p &amp;#x3c; .01). For 1000m network buffers (NDVI r = -0.34; green landcover r = -0.12; tree canopy r = 0.05, p &amp;#x3c; .01) two of the correlations became negative. Circular and network buffer were most highly correlated for the tree canopy (1000m r = 0.92; 400m r = 0.86, p &amp;#x3c; .01), whereas park count had the weakest correlation (1000m r = 0.66; 400m r = 0.66, p &amp;#x3c; .01). CONCLUSIONS: The associations between greenspace metrics vary. Selection of buffering method may be particularly influential when using park count data. These findings support the importance of intentional selection of greenspace metric and measurement method in environmental epidemiological research. KEYWORDS: greenspace metrics, NDVI, tree canopy cover, parks, network buffers, and circular buffers

Early Life Exposure to Greenspace and Autism Spectrum Disorder and the Mediating Effects of Air Pollution in Ontario, Canada

BACKGROUND AND AIM Early life exposure to greenspace is associated with health benefits on childhood development, but the pathways of this relationship are not completely understood. This study aimed to evaluate early life exposure to different greenspace metrics on the development on autism spectrum disorder (ASD) and whether these associations are mediated by reductions in ambient air pollution. METHODS This case-control study included 1,801 ASD cases and 9002 controls less than 5 years of age identified from 2012 to 2017 using health administrative databases in the province of Ontario, Canada. Greenspace metrics were estimated using the Normalized Difference Vegetation Index (NDVI), Green View Index (GVI) and percent tree canopy coverage using values within 250 m of participants’ residential postal codes at birth. Conditional logistic regression was used to investigate associations between greenspace exposure and ASD while adjusting for maternal age, parity, maternal comorbidities, substance use (i.e. smoking and alcohol), socioeconomic status and urbanicity. We estimated the mediation effects of nitrogen dioxide (NO2), fine particulate matter (PM2.5), and ozone (O3) using causal mediation analyses. RESULTS In the adjusted model, we found that one interquartile range (IQR) increase in percentage tree canopy was associated with a 6% reduction in the odds of ASD (Odds ratio = 0.94; 95% CI: 0.90, 0.98). No associations were found for NDVI and GVI in relation to ASD. We found that 81.8% (77.6 – 85.9), 20.1% (16.6 – 23.6) and 13.6% (11.1 – 16.0) of the association between tree canopy exposure and ASD was mediated through reductions in NO2, PM2.5, and O3, respectively. CONCLUSIONS Early life exposure to greenspace might reduce the risk of ASD through reductions in ambient air pollution, in particular traffic pollution from NO2. Our findings may provide support to communities on the potential health benefits of greenspaces.

Quantification of green and walkable neighbourhoods across the distribution of social and material deprivation in Metro Vancouver, Canada

BACKGROUND &amp;#x26; AIM: Along with other environmental exposures, both neighbourhood walkability, and greenspace exposure and access have been linked to many diverse health benefits. Previous work has examined the spatial relationship of built and natural environments according to levels of neighbourhood deprivation; however, less is known about how these relationships may vary when different greenspace metrics are used. This work examines how normalized differences vegetation index (NDVI), tree canopy cover, green land cover, and park count metrics relate to walkability, and how these neighbourhood characteristics associate with both social and material deprivation. METHODS: Greenspace exposure was measured using NDVI, tree canopy cover, and green land cover, while park access was quantified by the number of designated public parks within 1000m and 400m network buffers for each six-digit postal-code centroid in Metro Vancouver, Canada. Local area deprivation was measured using the 2016 Material and Social Deprivation Index (MSDI). Pearson’s correlation coefficients were calculated to compare these neighbourhood characteristics. RESULTS: Walkability was positively associated with social deprivation (1000m r = 0.48; 400m r = 0.48, p &amp;#x3c; .01), while walkability has a weak inverse relationship with material deprivation (1000m r = -0.21, p &amp;#x3c; .01). Tree canopy was negatively related to both social (1000m r = -0.23, 400m r = -0.23, p &amp;#x3c; .01) and material deprivation (1000m r = -0.24, 400m r = -0.23, p &amp;#x3c; .01). In contrast, the relationship between park count and both deprivation measures was weak. CONCLUSION: In this study, areas with greater social and material deprivation tend to have less greenspace, but not necessarily less park access. The identification of neighbourhoods with higher material deprivation, low walkability, and low greenspace, may be prioritized by urban planners and decision makers as possible locations for additional greenspace allocation. KEYWORDS: greenspace, walkability, social deprivation, material deprivation

Investigation on urban greenspace in relation to sociodemographic factors and health inequity based on different greenspace metrics in 3 US urban communities

BackgroundStudy results are inconclusive regarding how access to greenspace differs by sociodemographic status potentially due to lack of consideration of varying dimensions of greenspace.ObjectiveWe investigated how provision of greenspace by sociodemographic status varies by greenspace metrics reflecting coverage and accessibility of greenspace.MethodsWe used vegetation levels measured by Enhanced Vegetation Index (EVI), percent of greenspace, percent tree cover, percent tree cover along walkable roads, and percent of people living ≤500 m of a park entrance (park accessibility). We considered data for 2008–2013 in Census block groups in 3 US regions: New Haven, Connecticut; Baltimore, Maryland; and Durham, North Carolina. We examined geographical distribution of greenspace metrics and their associations with indicators of income, education, linguistic isolation, race/ethnicity, and age. We used logistic regression to examine associations between these greenspace metrics and age-standardized mortality controlling for sociodemographic indicators.ResultsWhich region had the highest greenspace depended on the greenspace metric used. An interquartile range (33.6%) increase in low-income persons was associated with a 6.2% (95% CI: 3.1, 9.3) increase in park accessibility, whereas it was associated with 0.03 (95% CI: −0.035, −0.025) to 7.3% (95% CI: −8.7, −5.9) decreases in other greenspace metrics. A 15.5% increase in the lower-education population was associated with a 2.1% increase (95% CI: −0.3%, 4.6%) in park accessibility but decreases with other greenspace metrics (0.02 to 5.0%). These results were consistent across the 3 study areas. The odds of mortality rate more than the 75th percentile rate were inversely associated with all greenspace metrics except for annual average EVI (OR 1.27, 95% CI: 0.43, 3.79) and park accessibility (OR 1.40, 95% CI: 0.52, 3.75).SignificanceEnvironmental justice concerns regarding greenspace differ by the form of natural resources, and pathways of health benefits can differ by form of greenspace and socioeconomic status within communities.Impact statementComparisons of exposure to greenspace between different greenspace metrics should be incorporated in decision-making within local contexts.