Associations Between Urban Green Space Quality and Mental Wellbeing: Systematic Review

Urbanisation is accelerating, with over two-thirds of the global population expected to live in cities by 2050. While cities provide economic and technological benefits, rapid urban growth has reduced green spaces and negatively affected residents’ mental wellbeing. Urban green spaces (UGSs) are widely reported to provide psychological benefits through exposure to nature and via pathways such as recreation, physical activity, and social connection. However, most prior work assesses greenness quantity (e.g., NDVI, area) or basic features (e.g., accessibility), whereas emerging evidence suggests the quality of UGSs may be a crucial determinant of mental wellbeing outcomes. Quality dimensions include spatial features (layout, size, accessibility), natural elements (vegetation and biodiversity, water features), and facilities/amenities (paths, seating, sports equipment) and their maintenance. The definition and measurement of UGS quality remain inconsistent, creating knowledge gaps about which qualities most strongly influence mental health. This systematic review aims to identify and categorise UGS quality aspects examined in primary studies and to evaluate their associations with mental wellbeing.

Prior research demonstrates mental health benefits from exposure to nature and urban greenspaces, with suggested mechanisms including recreation, physical activity, and social cohesion. Reviews have assessed long-term exposure to residential green/blue spaces and general health outcomes, and scoping/narrative reviews have summarised nature contact measurement and mediators between green space and mental health. However, studies focusing on UGS quality are comparatively fewer and heterogeneous in their definitions and measurement approaches. Evidence indicates biodiversity can enhance wellbeing, though some natural elements (e.g., pollen) may pose risks; amenities attract use but require effective design and maintenance; cleanliness and safety influence perceived quality and use. There is a notable gap in understanding how specific quality components (e.g., vegetation diversity vs. avian diversity; dynamic vs. still water; path design and surrounding road networks; maintenance and incivilities) contribute to mental wellbeing. This review addresses these gaps by systematically synthesising studies that objectively measured UGS quality and linked it to mental wellbeing outcomes.

The review followed PRISMA 2020 guidelines and was registered on PROSPERO (CRD42023462427). Databases searched included Web of Science (Core Collection), MEDLINE (via WOS), PubMed, Scopus, and Cochrane Library. The search covered English-language research articles from 2013 through 2025 (early-access), with no geographic or population restrictions. The search strategy combined terms for mental wellbeing outcomes (e.g., mental health, depression, anxiety, stress, restoration), green space quality (e.g., quality, spatial features, landscape patterns, vegetation cover, NDVI, accessibility, facilities, amenities, maintenance, safety features), and urban green space types (e.g., urban park, urban garden, green infrastructure). Inclusion criteria followed PICOTS: Participants—urban residents with access to UGS (studies focusing on minors excluded due to proxy reporting); Intervention—exposure to UGS quality features (spatial features, natural elements including blue elements within green spaces, facilities/amenities and their maintenance); Outcomes—general mental wellbeing or core psychological indicators (depression, anxiety, stress, attention restoration, positive/negative affect, life satisfaction); Study designs—original studies (cross-sectional, cohort, case-crossover, quasi-experimental, before-after, ecological). Exclusions included studies focusing only on quantity (e.g., area) or accessibility as standalone measures, blue spaces alone, urban vs. rural comparisons, remote viewing (windows, VR, photos, soundtracks), non-publicly accessible UGSs, and studies relying solely on subjective quality perceptions without objective measures. Study selection used EndNote for management; duplicates were removed. Titles/abstracts were screened, followed by full-text screening with reasons for exclusion recorded; disagreements were discussed and resolved. Data extraction captured author, year, location, design, population, quality measurements/instruments, wellbeing outcomes/instruments, mediators/moderators/covariates, statistical methods, and findings. Methodological quality was assessed using a modified version of Gascon et al. (2015) criteria (11 items; percent score categorised as poor, fair, good, excellent), with specific items adapted to fit this review’s context.

• Study sample: 22 articles (2017–2024); countries mostly China (n=11) and UK (n=3), plus Taiwan, Hong Kong, Australia, Turkey, Guyana, Pakistan; one study across four European countries. Designs: 18 cross-sectional, 4 quasi-experimental, 1 longitudinal. Sample sizes ranged from 30 to 3771.
• Quality assessment: 3 studies rated excellent, 13 good, 5 fair, 1 poor.
• Mental wellbeing outcomes: Diverse measures used—general wellbeing (WHO-5, GHQ-12), emotions (PANAS; positive/negative affect), depression (MHI-5, GDS-15), attention restoration (PRS), stress/anxiety (various scales), life satisfaction (SWLS). Objective physiological indicators were rare; two studies used measures such as blood pressure, pulse, EEG, and wearable sensors (EDA, EMG, RESP, SKT, PPG).
• Spatial features: Accessibility exhibited mixed associations—linked to reduced stress, less depression, and higher life satisfaction in some studies, but null in others; benefits mediated by environmental perceptions and park type/scale. Larger, comprehensive parks sometimes yielded greater wellbeing benefits than nearby small parks. Green coverage and rational spatial layout correlated with reduced environmental stressors and improved satisfaction; uneven terrain aided stress recovery and attention restoration (not applicable to older adults). Openness showed negligible effects.
• Natural elements: Most consistent positive associations. Vegetation diversity, species richness, and well-maintained, aesthetically diverse plantings were linked to stress reduction, attention restoration, and improved mood. Water features contributed substantially; dynamic water (streams, waterfalls) enhanced stress reduction and attention focusing, while still water (lakes, ponds) supported meditation and emotional stability. Combined green-blue elements amplified restorative potential. Avian diversity results were mixed; perceived biodiversity often showed stronger associations with wellbeing than measured biodiversity. Visibility and accessibility of natural features influenced effectiveness. Some evidence suggested shrubs may be less beneficial than trees.
• Facilities and amenities: Complex and context-dependent. Well-maintained walking paths and comfortable pedestrian infrastructure were generally beneficial, but surrounding road networks could increase stress and reduce restoration. Sports facilities showed both positive and negative associations (noise/crowding effects), with benefits less evident among older adults. Rest facilities (benches, seating) tended to be positive, contingent on quality and maintenance. Lighting, safety features, and general maintenance enhanced benefits; incivilities and poor maintenance reduced them. Cultural landscape and non-natural aesthetic features sometimes supported attention restoration; spatial privacy and cleanliness showed limited or nonsignificant effects.
• Combined quality assessments: High ecological quality (e.g., Sites of Importance for Nature Conservation) associated with greater life satisfaction and general wellbeing versus ordinary open spaces. Street-view green space quality influenced mental wellbeing indirectly via social cohesion, physical activity, and stress reduction, with significant improvements in depression and anxiety in some settings.

The review addresses the central question of how UGS quality relates to mental wellbeing by synthesising evidence across spatial features, natural elements, and facilities/amenities. Findings underscore that natural elements—especially vegetation diversity and water features—consistently contribute to stress reduction, attention restoration, and improved emotional states, supporting biophilia-based mechanisms. Spatial features such as accessibility show heterogeneous effects, suggesting that simplistic proximity metrics may not capture experiential quality; park type, scale, and perceived environment mediate benefits. Facilities and amenities exert nuanced impacts: design quality, maintenance, and contextual factors (noise, crowding, adjacent road networks) can enhance or undermine restorative potential. The prominence of perceived biodiversity over measured biodiversity indicates subjective experience plays a critical role alongside objective quality metrics. The relative scarcity of objective physiological assessments highlights a methodological gap; integrating wearable and sensor-based measures with standardised, validated quality tools would strengthen causal inference. Overall, the results advocate for integrated, user-centered UGS planning that balances ecological quality, spatial design, amenities, and maintenance to optimise mental health outcomes across diverse populations.

UGS quality is a key determinant of mental wellbeing, yet its definition and measurement remain heterogeneous. Natural elements—particularly vegetation diversity and water features—show robust positive associations with mental health, while spatial features like accessibility yield mixed results. Facilities and amenities can provide benefits but are highly dependent on design context, maintenance, and avoidance of incivilities. Current evidence is dominated by cross-sectional studies and varied outcome measures, limiting comparability and causal interpretation. Future research should adopt standardised quality assessment frameworks, employ rigorous experimental and longitudinal designs, and integrate objective physiological measures to elucidate mechanisms and strengthen causal inference. Planning and policy should prioritise ecological quality, diverse and well-maintained natural elements, context-sensitive amenities, and safety to maximise mental wellbeing benefits from UGSs.

The review included a relatively small number of eligible studies due to strict inclusion criteria focusing on objective quality measures and core mental wellbeing outcomes. Substantial heterogeneity in quality metrics and outcome assessments complicated cross-study comparisons. Most studies were cross-sectional, limiting causal inference. Objective physiological measurements were rarely used, and field-based experimental research on real UGS exposure remains limited. Only English-language publications were included, potentially missing non-English studies. Studies focusing on minors were excluded due to reliance on proxy reports, limiting applicability to younger populations. Future work should broaden language inclusion, incorporate objective assessments for minors, and expand field-based experimental and longitudinal approaches.