Neighborhood Greenness Research Articles

Neighborhood Aesthetics as a Correlate of Physical and Mental Health

Background/Aim: Evidence of associations between nature and health is mounting. However, there is a need to deconstruct “natural space” to capture quality in addition to and the various ways they impact on health. In this paper, we test associations between a quality-based index of neighborhood aesthetics and satellite-observed measure of greenspace and their relationships to health. Method: Using a population-based sample of 2696 adults in four European cities from the PHENOTYPE study, we examined the association between quality-based index of neighborhood aesthetics (13 items on perceived amount, appeal and satisfaction of nearby green space; α=0.86) and the satellite-generated Normalized Difference Vegetation Index (NDVI) and mental and physical health. General health status was assessed using the Short-Form (SF)-36 question to self-rate health (5-point response scale: excellent to poor). Mental health was assessed using the SF-36 mental health subscale, including five items about the occurrence of symptoms in the past 4 weeks (e.g., nervousness, depression) (6-point response scale: all of the time to none of the time).Results: The results from multi-level analyses adjusted for demographic and socioeconomic factors showed that in the pooled analysis, the neighborhood aesthetics index was associated with better self-rated mental (β=0.32 (0.24, 0.40)) and physical health (odds ratio=1.05 (1.03, 1.08)) while satellite-observed neighborhood greenness was not. These results were consistent across the four cities, even though they differ in aesthetics ratings and green space availability.Conclusions: This research suggests that community planners and health professionals can target interventions that foster positive neighborhood aesthetic experiences as a way to initiate health promotive processes that lead to improved mental and physical health. Satellite-observed greenness may miss important elements of the nearby green environment when assessing association between green space and health. Rather, street-based directly observed data provide a more accurate picture of the street green environment that affects populations.

Modelling and mapping eye-level greenness visibility exposure using multi-source data at high spatial resolutions

The visibility of natural greenness is associated with several health benefits along multiple pathways, including stress recovery and attention restoration mechanisms. However, existing methodologies are inadequate for capturing eye-level greenness visibility exposure at high spatial resolutions for observers located on the ground. As a response, we developed an innovative methodological approach to model and map eye-level greenness visibility exposure for 5 m interval locations within a large study area. We used multi-source spatial data and applied viewshed analysis in conjunction with a distance decay model to compute a novel Viewshed Greenness Visibility Index (VGVI) at more than 86 million observer locations. We compared our eye-level visibility exposure map with traditional top-down greenness exposure metrics such as Normalised Differential Vegetation Index (NDVI) and a Street view based Green View Index (SGVI). Furthermore, we compared greenness visibility at street-only locations with total neighbourhood greenness visibility. We found strong to moderate correlations (r = 0.65–0.42, p < 0.05) between greenness visibility and mean NDVI, with a decreasing trend in correlation strength at increasing buffer distances from observer locations. Our findings suggest that top-down and eye-level measurements of greenness are two distinct metrics for assessing greenness exposure. Additionally, VGVI showed a strong correlation (r = 0.481, p < 0.01) with SGVI. Although the new VGVI has good agreement with existing street view based measures, we found that street-only greenness visibility values are not wholly representative of total neighbourhood visibility due to the under-representation of visible greenness in locations such as backyards and community parks. Our new methodology overcomes such underestimations, is easily transferable, and offers a computationally efficient approach to assessing eye-level greenness exposure.

Association Pathways Between Neighborhood Greenspaces and the Physical and Mental Health of Older Adults-A Cross-Sectional Study in Guangzhou, China.

According to the United Nations, the proportion of the older population is increasing at a faster rate than all other age groups. Hence, the well-being of older adults is a mounting concern worldwide in the current century. Using a single greenery metric, previous studies linked greenness to residents' well-being. This study aims to extend this field by focusing on the mental and physical well-being of older adults by using remote sensing and streetscape metrics in evaluating neighborhood greenness. We selected 20 residential neighborhoods in Guangzhou City, China as the cross-sectional case study areas. We investigated neighborhood normalized difference vegetation index (NDVI) collected using remote sensing images, streetscape greenery, and PM2.5 via field surveys. We assessed the health condition of 972 senior residents selected by multi-stage stratified probability proportionate to population size sampling technique (PPS) using a questionnaire survey. We adopted the structural equation model (SEM) in analyzing the pathways that link neighborhood greenness and the mental and physical health of older adults. We found that neighborhood greenness has a positive association with the physical activity by older adults that is positively linked to their physical health. Moreover, neighborhood greenness is positively related to regular social interactions among older adults that is positively linked to their mental health. These findings are consistent with those of previous studies. However, we obtained new results that were unique to China. We found that neighborhood greenness has no significant direct relationship with the physical and mental health of older adults and that social interactions of low-income senior groups are more substantially related to neighborhood greenness than the other groups. Therefore, community planning should emphasize the development of neighborhood greenness, such as parks and street trees, to provide natural spaces for social interactions and places for physical activities among older residents.

Establishing associations between residential greenness and markers of adiposity among middle-aged and older Chinese adults through multilevel structural equation models.

Residential greenness may prevent overweight/obesity, but the matter has not been investigated among middle-aged and older adults in China. This study 1) assessed associations between residential greenness and markers of adiposity among middle-aged and older Chinese adults and 2) investigated physical activity, sedentary behaviours, particulate matter (PM) with a diameter of <2.5μm (PM2.5) concentrations, and perennial mean temperature as mediators of the associations. We used data from the World Health Organization's Study on Global Ageing and Adult Health (SAGE) between 2007 and 2010. Overweight/obesity and abdominal obesity were measured by body mass index and waist circumference. Exposure to neighbourhood greenness was measured by the normalized difference vegetation index (NDVI). Multilevel structural equation models were fitted to investigate the associations between neighbourhood greenness, the four potential mediators, and the prevalence of overweight/obesity and central obesity. The results showed that greenness was inversely associated with the odds of overweight/obesity (odds=0.73, 95% confidence interval (CI) 0.58-0.92) and abdominal adiposity (odds=0.55, 95% CI 0.33-0.91). The greenness-overweight/obesity association varied significantly by sex and age, and the greenness-central obesity varied significantly by sex, age, and education. We found some indication that PM2.5 concentrations had a suppressive effect on the greenness-adiposity associations. There was no evidence that physical activity, sedentary behaviours, and perennial mean temperature mediated the associations between neighbourhood greenness and markers of adiposity. Exposure to higher levels of residential greenness was associated with lower odds of overweight/obesity and abdominal obesity among middle-aged and older Chinese adults. However, underlying mechanisms explaining these associations remain unclear requiring longitudinal studies and natural experiments.

Urbanization and greenness in HBSC survey: association with life satisfaction and health complaints

Abstract Background Several studies have shown that neighborhood greenness is associated with lower problematic behaviors in children and better perceived well being. While urbanization showed opposite results. The aim of the study was to assess the relationship between urbanization and greenness levels with perceived health, life satisfaction and health complaints on adolescents. Methods The study is based on data from 2018 Health Behavior in School-aged Children in the region of Piedmont(Italy), which involved 3022 11-,13-,15-year olds, sampled in 122 schools across the region. Every school was georeferenced. Greenneess was measured by Normalised Difference Vegetation Index (NDVI-satellite images) and urbanization by population density, traffic intensity (satellite measurements) and air pollution concentration (sampling stations). Health complaints were evaluated with a set of 8 psychosomatic symptoms(reported more than once a week). Life Satisfaction (LS) was measured by using the Cantril scale (low LS &amp;lt; 5, high LS &amp;gt; =6). Self-Rated Health was measured by means of a four points scale (fair or poor, good or excellent). Results More than 66% of adolescents reported frequent health complaints; 11% declared low life-satisfaction and 9% of adolescents scored poor or fair self-rated health. The proportion of the three variables increased with age in both genders, and was higher among girls. Gender differences increased from 11- to 15-years of age. Preliminary results showed a positive association between greenness and life satisfaction, urbanization and health complaints. Conclusions In times of increasing urbanization and reduced availability of green areas, characterizing the association between urbanization, greenness and perceived health is revealed to be the challenge for Public Health. Redefine the urban spaces accordingly requires collaboration between different disciplines. Coherently with the recent studies, communities can be actively involved through qualitative approaches. Key messages The topic of urban nature is becoming central for healthy and sustainable urban planning, not the least for population groups like adolescents and children. The relation between urbanization, with decreasing access to green spaces, and the impact on physical as well as mental health presents an important issue and a big challenge for Public Health.

Youth and weapons: Patterns, individual and neighborhood correlates of violent crime arrests in Miami-Dade County, Florida.

This study uses arrest data from the Miami-Dade County Police Department (n=13 districts) for 2014-2017 to identify census tracts in which weapon violence arrests among young people aged 10-24 is high, and models area-level predictors of the total number of violent weapons crimes by census tract (greenness and socioeconomic status indices, population density and weapon dealers), after adjusting for arrestee-level factors (age, race and gender). Combined, handguns and firearms accounted for 23.2% (n=1330) of all arrests (including murder and non-negligent manslaughter, rape, robbery, and aggravated assault). Arrests for weapon -related violent crime are concentrated in census tracts located in the north and south neighborhoods of Miami-Dade County. Findings indicate that arrestee factors and a neighborhood greenness index are more important than population density, weapon dealers and poverty in predicting arrests for weapon-related violent crime at the census tract level.

Neighborhood greenness associated with chronic obstructive pulmonary disease: A nationwide cross-sectional study in China

Differential findings have been reported on the association between neighborhood greenness and chronic obstructive pulmonary disease (COPD). The underlying reasons might be the different types of vegetation and the diagnosis methods used in different studies. In this nationwide cross-sectional study in China, we examined the linkage between neighborhood greenness and COPD prevalence among 66,752 adults aged 40 years and above. Neighborhood greenness was estimated using the normalized difference vegetation index (NDVI) based on satellite imagery within buffers of 100, 300, 500, 1000, 2000, 3000 and 5000 m of residential community of the participants. COPD was defined according to the 2017 Global Initiative for Chronic Obstructive Lung Disease lung function criteria. A two-level logistic regression model was applied to estimate the associations. Finally, 9134 adults were classified as COPD. We observed significant positive associations between neighborhood greenness and COPD prevalence. The odds ratio for each interquartile range increase in NDVI within 100 m buffer was 1.08 (95% CI: 1.01, 1.15) after adjustment for potential confounders. Consistent associations were observed across all other NDVI buffer sizes. Stratified analyses revealed that younger adults (40–65 years) and urban residents might be the vulnerable subpopulations. Further regional analyses found that residents from the Northeastern and Northern China were more likely to have this association. Our results indicated that neighborhood greenness might be one risk factor of COPD prevalence. Our study have important public health implications for allocating the surrounding green spaces among living areas, especially for those with respiratory illness; however, the findings and the underlying mechanisms warrant further examinations in longitudinal settings.

Does Green Space Really Matter for Residents' Obesity? A New Perspective From Baidu Street View.

Despite a growing literature on the topic, the association between neighborhood greenness and body weight is inconsistent. The objective of this research is to examine the association between neighborhood greenness and residents' obesity levels in a high population density area. We accounted for three greenness features: green access, green exposure, and view-based green index. We used the novel technique of deep convolutional neural network architecture to extract eye-level information from Baidu Street View images to capture the urban vertical greenness level. The research involved a survey with 9,524 respondents from 40 communities in Shanghai. Generally, we found all aspects of horizontal greenery, vertical greenery, and proximity of green levels to be impactful on body weight; however, only the view-based green index consistently had an adverse effect on weight and obesity.

Cross-sectional associations of neighbourhood socioeconomic disadvantage and greenness with accelerometer-measured leisure-time physical activity in a cohort of ageing workers

ObjectiveNeighbourhood characteristics may affect the level of physical activity (PA) of the residents. Few studies have examined the combined effects of distinctive neighbourhood characteristics on PA using objective data or...

Compensation or cosmopolitan attitudes: Explaining leisure travel of Nordic urbanites

Inner cities have been recently linked to a higher volume of long-distance travel for leisure purposes of their residents when compared to suburban and rural areas. The compensation hypothesis proposes that this difference results from urban residents’ tendency to travel away to compensate for poor access to green spaces or to escape urban stressors. This paper tests two versions of this hypothesis using two softGIS surveys of young adults living in the capital regions: Helsinki in Finland and Reykjavik in Iceland. We also examine an alternative hypothesis of cosmopolitan attitude as the explaining factor. We consider the levels of consonance or dissonance between the residential preferences and the GIS-measured characteristics of residential environments, attitudes towards travel, and socio-demographic and lifestyle characteristics of respondents. We found weak and contextual support for the compensation hypothesis: neighborhood greenness was related to the number of trips in Helsinki, but not in Reykjavik. In both cities, the trend of increasing trip numbers along with the distance to the city center was explained mainly by the spatial clustering of cosmopolitan attitudes in the city centres. Private car ownership and summer cottage access were also significant predictors of domestic trips frequency. Overall the results suggest that the compensation effect is neither exclusive nor the most plausible explanation for differences in travel patterns between urban dwellers. Still, it might be at play in some circumstances. The results do not challenge compact city policies but suggest paying attention to additional travel demand due to the inadequacies of urban environments.

Green Apartheid: Urban green infrastructure remains unequally distributed across income and race geographies in South Africa

Urban green infrastructure provides ecosystem services that are essential to human wellbeing. A dearth of national-scale assessments in the Global South has precluded the ability to explore how political regimes, such as the forced racial segregation in South Africa during and after Apartheid, have influenced the extent of and access to green infrastructure over time. We investigate whether there are disparities in green infrastructure distributions across race and income geographies in urban South Africa. Using open-source satellite imagery and geographic information, along with national census statistics, we find that public and private green infrastructure is more abundant, accessible, greener and more treed in high-income relative to low-income areas, and in areas where previously advantaged racial groups (i.e. White citizens) reside. Areas with White residents report 6-fold higher income, have 11.7% greater tree cover, 8.9% higher vegetation greenness and live 700 m closer to a public park than areas with predominantly Black African, Indian, and Coloured residents. The inequity in neighborhood greenness levels has been maintained (for Indian and Coloured areas) and further entrenched (for Black African areas) since the end of Apartheid in 1994 across the country. We also find that these spatial inequities are mirrored in both private (gardens) and public (street verges, parks, green belts) spaces, hinting at the failure of governance structures to plan for and implement urban greening initiatives. By leveraging open-access satellite data and methods presented here, there is scope for civil society to monitor urban green infrastructure over time and thereby hold governments accountable to addressing environmental justice imperatives in the future. Interact with the data here: green-apartheid.zsv.co.za.

Perceived greenness at home and at university are independently associated with mental health

BackgroundPrevious studies reported positive associations between perceived neighborhood greenness and mental health. There has been a focus on perceived neighborhood greenness at people’s home environment or in general, but data are lacking on greenness at working places or other locations where they actually spend most of their time during their day.MethodsThis study investigated the perceived greenness of college students’ home and study environments and its relation to mental health. An online survey collected data from 601 participants with a mean age of 24 years, living in or around and studying in the city of Graz, Austria. The perceived greenness at home and at university was assessed using questions on quality of and access to green space; mental health was measured with the WHO-5 well-being index. Uni- and multivariate regression analyses were used to analyze the data.ResultsThe analyses revealed positive associations between perceived greenness at home and mental health as well as perceived greenness at university and mental health. This adds more evidence to the existing literature that perceiving the environment as green is positively related to better mental health.ConclusionsFuture research will have to incorporate objective greenness measures as a means of controlling for the reliability of the measurements and investigate the effects of different environments people are exposed to over the course of a day.

Objective and Perceived Neighborhood Greenness of Students Differ in their Agreement in Home and Study Environments.

Research has reported the associations between objective or subjective neighborhood greenness and health, with low agreement between the greenness scores. College students are prone to poor health, and data are lacking on home and university environments. We studied the agreement between greenness parameters and the associations of objective greenness with health in different locations. Three hundred and seventy-seven college students were recruited, with a mean age of 24 years, in the city of Graz, Austria. Objective and perceived greenness was assessed at home and at university. Health measures included the WHO-5 questionnaire for mental health, the IPAQ questionnaire (short) for physical activity and sedentariness, and body mass index. Per location, quintile pairs of objective and perceived greenness were classified into underestimates, correct estimates or overestimates. Interrater reliability and correlation analyses revealed agreement between greenness scores at home but not at university. ANOVA models only showed poorer mental health for students underestimating greenness at university (M = 51.38, SD = 2.84) compared to those with correct estimates (M = 61.03, SD = 1.85). Agreement between greenness scores at home but not at university was obtained, and mental health was related to the perception of greenness at university. We conclude that reliable and corresponding methods for greenness scores need to be developed.

The association between neighborhood greenness and incidence of lethal prostate cancer: A prospective cohort study.

Growing evidence suggests that neighborhood contextual environment could influence risk factors and, therefore, incidence of lethal prostate cancer. We studied the association between neighborhood greenness and lethal prostate cancer incidence and assessed mediation by vigorous physical activity. A total of 47,958 participants were followed in the Health Professionals Follow-up Study from 1986 to 2014. Neighborhood greenness exposure was estimated using normalized difference vegetation index (NDVI) with 1 km resolution, assigned to home or work addresses at start of follow-up. Adjusted hazard ratios (aHRs) and 95% confidence intervals (CIs) were estimated using sequentially adjusted Cox models with individual and contextual prostate cancer risk factors as covariates. Analyses were compared among those whose addresses were constant over follow-up and stratified by population density and address type. We observed 898 cases over 1,054,743 person-years. An interquartile range increase in NDVI was associated with 5% lower rate of lethal prostate cancer (aHR = 0.95, 95% CI = 0.88, 1.03), with stronger associations in nonmovers (aHR = 0.92, 95% CI = 0.85, 1.01). Inverse associations were observed among men in high (aHR = 0.90, 95% CI = 0.82, 0.99) but not low (aHR = 1.11, 95% CI = 0.95, 1.29, P het = 0.086) population density areas, and those reporting from work (aHR = 0.87, 95% CI = 0.75, 1.01) but not home (aHR = 1.04, 95% CI = 0.91, 1.17, P het = 0.10) addresses. There was no evidence of mediation by vigorous physical activity. We report inverse associations between neighborhood greenness and lethal prostate cancer when restricting to nonmovers and in high population density areas. Replication could confirm findings and clarify mechanisms.

사회경제적 지위에 따른 대구시 근린공원 질적 가치 형평성†

In terms of environmental justice, urban parks play a pivotal role in imperative amenities allowing for physical activity. The reasonable distribution of urban park services must be considered in terms of community demand and the context of the park. The purpose of this study is to analyze the inequity of qualitative park service according to the socioeconomic status(SES) in Daegu. The qualitative service was assessed for 82 neighborhood and walking-distance parks by utilizing the NGST(Neighborhood Green Space Tool). The inequity was analyzed by SES variables(ratio of basic living recipients, ratio of single-parent families, average housing sales, dilapidated dwelling ratio, and park area per capita). The features of the qualitative equity in Daegu is as follows. First, urban park planning in Daegu is in parallel with the development of residential areas rather than the local policy. The development pattern of parks stretching from center of the city to outskirts clearly dissociates the city based on socioeconomic status. The parks in the center are relatively old and poorly managed. Second, overall neighborhood parks lacked recreational facilities. The facilities are significantly influenced by the housing values around them. The lower the recreation facility score, the higher the floor gradient of the urban parks constraining physical activities. Third, the quantitative supply of parks has nothing to do with the quality of the urban parks. Green space distribution is highly dependent on natural park areas, so the park area per capita cannot be a standard for assessing qualitative equity.

Air pollution associated respiratory mortality risk alleviated by residential greenness in the Chinese Elderly Health Service Cohort

BackgroundAlthough residing in lower surrounding greenness and transient exposure to air pollution are independently associated with higher risk of adverse health outcomes, little is known about their interactions. ObjectivesWe examine whether residential neighborhood greenness modifies the short-term association between air pollution and respiratory mortality among the participants of Chinese Elderly Health Service Cohort in Hong Kong. MethodsWe estimated residential surrounding greenness by measuring satellite-derived normalized difference vegetation index (NDVI) from Landsat within catchments of residential addresses of participants who died of respiratory diseases between 1998 and 2011. We first dichotomized NDVI into low and high greenness and used a time-stratified case-crossover approach to estimate the percent excess risk of respiratory mortality associated with fine particulate matter (PM2.5), respirable particulate matter (PM10), nitrogen dioxide (NO2), and ozone (O3). We further classified NDVI into greenness quartiles and introduced an interaction term between air pollution and the assigned median values of the NDVI quartiles into the models to assess the trend of greenness modification on the air pollution and respiratory mortality associations. ResultsAmong 3159 respiratory deaths during the follow-up, 2058 were from pneumonia and 947 from chronic obstructive pulmonary disease. Elders living in the low greenness areas were associated with a higher risk of pneumonia mortality attributed to NO2 (p = 0.049) and O3 (p = 0.025). The mortality risk of pneumonia showed a decreasing trend for NO2 (p for trend = 0.041), O3 (p for trend = 0.006), and PM2.5 (p for trend = 0.034) with greenness quartiles increasing from Quartile 1 (lowest) to Quartile 4 (highest). ConclusionsOur findings suggest that elders living in higher greenness areas are less susceptible to pneumonia mortality associated with air pollution, which provides evidence for optimizing allocation, siting, and quality of urban green space to minimize detrimental health effects of air pollution.

Sedentariness of College Students Is Negatively Associated with Perceived Neighborhood Greenness at Home, but Not at University.

Previous studies reported contradictory evidence for associations between perceived greenness and obesity mediated by physical activity, focusing on people’s homes or general greenness. Data are lacking in other environments. We studied the association of perceived greenness at home and at university with BMI and physical activity. An online survey collected data from 601 participants, living and studying in and around the city of Graz, Austria; mean age of 24 years. Greenness was assessed using questions on quality of and access to green space; Body mass index (BMI) was derived from self-reported measures; physical activity and sedentariness were measured using the IPAQ questionnaire (short version). On average, BMI was 22.6 (SD = 3.7), physical activity was 63.3 (SD = 51.7) METh/week, and participants spent 5.8 (SD = 4.0) h/day sitting. Regression analyses revealed no associations between perceived greenness and BMI and physical activity for all environments, but a negative association for sedentariness and perceived greenness at home, but not at university. The results indicate a relation between perceived greenness and sedentariness, which differs for the home-and study environment.

Residential greenness and increased physical activity in patients after coronary artery bypass graft surgery.

Physical activity is a fundamental component of rehabilitation following coronary artery bypass (CABG) surgery. Proximity to neighbourhood green spaces may encourage physical activity. We investigated the association between residential greenness and exercise-related physical activity post-CABG surgery. Participants in a prospective cohort study of 846 patients (78% men) who underwent CABG surgery at seven cardiothoracic units during the time period 2004-2007 were interviewed regarding their physical activity habits one day before and one year after surgery. Exposure to residential neighbourhood greenness (within a 300 m buffer around their place of residence) was measured using the Normalized Difference Vegetative Index. Participation in exercise-related physical activity (yes/no), weekly duration of exercise-related physical activity and the change in exercise-related physical activity between baseline and follow-up were examined for associations with residential greenness, adjusting for socio-demographic factors, propensity score adjusted participation in cardiac rehabilitation and health-related covariates after multiple imputation for missing variables. Living in a higher quartile of residential greenness was associated with a 52% greater odds of being physically active (OR 1.52, 95% CI 1.22-1.90). This association persisted only (OR 1.75, 95% CI 1.35-2.27) among patients who did not participate in cardiac rehabilitation following surgery and was stronger in women (OR 2.38, 95% CI 1.40-4.07) than in men (OR 1.37, 95% CI 1.07-1.75). Participants who lived in greener areas were more likely to increase their post-surgical physical activity than those who lived in less green areas (OR 1.59, 95% CI 1.25-2.01). Residential greenness appears to be beneficial in increasing exercise-related physical activity in cardiac patients, especially those not particpating in cardiac rehabilitation after CABG surgery.

Residential greenness, air pollution and psychological well-being among urban residents in Guangzhou, China

China’s rapid urbanization has led to an increasing level of exposure to air pollution and a decreasing level of exposure to vegetation among urban populations. Both trends may pose threats to psychological well-being. Previous studies on the interrelationships among greenness, air pollution and psychological well-being rely on exposure measures from remote sensing data, which may fail to accurately capture how people perceive vegetation on the ground. To address this research gap, this study aimed to explore relationships among neighbourhood greenness, air pollution exposure and psychological well-being, using survey data on 1029 adults residing in 35 neighbourhoods in Guangzhou, China. We used the Normalized Difference Vegetation Index (NDVI) and streetscape greenery (SVG) to assess greenery exposure at the neighbourhood level, and we distinguished between trees (SVG-tree) and grasses (SVG-grass) when generating streetscape greenery exposure metrics. We used two objective (PM2.5 and NO2 concentrations) measures and one subjective (perceived air pollution) measure to quantify air pollution exposure. We quantified psychological well-being using the World Health Organization Well-Being Index (WHO-5). Results from multilevel structural equation models (SEM) showed that, for parallel mediation models, while the association between SVG-grass and psychological well-being was completely mediated by perceived air pollution and NO2, the relationship between SVG-tree and psychological well-being was completely mediated by ambient PM2.5, NO2 and perceived air pollution. None of three air pollution indicators mediated the association between psychological well-being and NDVI. For serial mediation models, measures of air pollution did not mediate the relationship between NDVI and psychological well-being. While the linkage between SVG-grass and psychological well-being scores was partially mediated by NO2-perceived air pollution, SVG-tree was partially mediated by both ambient PM2.5-perceived air pollution and NO2-perceived air pollution. Our results suggest that street trees may be more related to lower air pollution levels and better mental health than grasses are.

Assessing the Impact of School-Based Greenness on Mental Health Among Adolescent Students in Ontario, Canada.

Neighbourhood greenness has been frequently associated with improved mental health in adulthood, yet its impact among youth is less clear. Additionally, though youth spend large portions of time at school, no study has investigated associations between school-based measures of greenness and students’ mental health in Canada. We addressed this gap by linking participant responses from the 2016–2017 Ontario Student Drug Use and Health Survey to school-based features of the built environment. Our analyses included 6313 students, ages 11–20. Measures of greenness were the mean and max of the annual mean Normalized Difference Vegetation Index within 500 m and 1000 m from the centroid of the school postal code. Measures of mental health included: serious psychological distress (Kessler 6-item Psychological Distress Scale), self-rated mental health (using a five-point Likert scale), suicide ideation, and suicide attempt. In our study population, the prevalence of serious psychological distress and low self-rated mental health was 16.7% and 20.3%, respectively. Suicide ideation was reported by 13.5% of participants, while 3.7% reported a suicide attempt. Quantity of greenness was similar between schools in the lower and upper quartiles. In logistic regressions, we found no association between objective school-based greenness and mental health, as assessed by multiple measures, both before and after adjustment. Null findings held true after stratification by season, as well. Whether other characteristics of school greenness (such as type, quality, or access and use) are more impactful to students’ mental health should be a focus of future analyses.