Exposure to blue space surroundings and depressive symptoms in young Chinese adults: The mediating role of sleep.

OBJECTIVE: Existing evidence suggests that the natural environment can influence mental health. However, limited research has focused on the relationship between blue space and depressive symptoms in young adults. To investigate the association between blue space surroundings and depressive symptoms in young adults in China and explore the underlying mechanisms. METHODS: The study was conducted between September and November 2019, including 2,743 young adults from China. We assessed the exposure to blue space around participants' living environments during June, July, and August 2019 using the Modified Normalized Difference Water Index (MNDWI). Blue indexes were calculated for 300 m, 1000 m, and 3000 m circular buffer zones near residential environments. Logistic regression models were employed to explore the associations between blue space exposures (quartiles) and depressive symptoms, exploring potential mechanisms through structural equation modeling (SEM), while accounting for potential confounders. Stratification analysis was used to identify sensitive populations. RESULTS: Depressive symptoms were found in 148 (5.3%) of the 2,743 young adults in the study. We observed a negative correlation between depressive symptoms and average MNDWIs at participants' addresses (OR: 0.84; 95%CI: 0.72-0.98), within 300m (OR: 0.81; 95%CI: 0.70-0.95), 1000m (OR: 0.80; 95%CI: 0.69-0.93), and 3000m (OR:0.77; 95%CI: 0.66-0.89) buffer zones. Within the 1000m buffer zone, sleep was found to mediate 21% of the relationship between the presence of blue space and depressive symptoms. The stratified analysis revealed a stronger association between low MNDWI levels within the 1000m buffer zone and depressive symptoms in females (P < 0.05). Additionally, average MNDWI levels within the 3000m buffer zone were associated with depressive symptoms in both females and males. CONCLUSIONS: Blue space could improve depressive symptoms, particularly in females, with sleep playing a mediating role. Incorporating blue spaces into environmental planning is important for improving mental health.

Five waves of the COVID-19 pandemic and green-blue spaces in urban and rural areas in Poland.

Several waves of COVID-19 caused by different SARS-CoV-2 variants have been recorded worldwide. During this period, many publications were released describing the influence of various factors, such as environmental, social and economic factors, on the spread of COVID-19. This paper presents the results of a detailed spatiotemporal analysis of the course of COVID-19 cases and deaths in five waves in Poland in relation to green‒blue spaces. The results, based on 380 counties, reveal that the negative correlation between the indicator of green‒blue space per inhabitant and the average daily number of COVID-19 cases and deaths was clearly visible during all waves. These relationships were described by a power equation (coefficient of determination ranging from 0.83 to 0.88) with a high level of significance. The second important discovery was the fact that the rates of COVID-19 cases and deaths were significantly higher in urban counties (low values of the green-blue space indicator in m2/people) than in rural areas. The developed models can be used in decision-making by local government authorities to organize anti-COVID-19 prevention measures, including local lockdowns, especially in urban areas.

'Lifts your spirits, lifts your mind': A co-produced mixed-methods exploration of the benefits of green and blue spaces for mental wellbeing.

INTRODUCTION: Mental health problems are a considerable public health issue and spending time in nature has been promoted as a way to access a range of psychological benefits leading to the development of nature-based interventions for people with severe and enduring mental health problems. Less, however, is understood about the potential benefits and efficacy of day-to-day routine access to outdoor green and blue spaces for mental health service users. METHODS: Using a mixed-methods design between April and October 2021, we explored the benefits and barriers to spending time outdoors with a purposive sample of mental health service users (N = 11) using qualitative interviews and an online general population survey (N = 1791). Qualitative evidence highlighted the restorative benefits of nature and identified a number of barriers associated with fears around personal safety, social anxiety, fatigue and lack of motivation. COVID-19 had also restricted access to green and blue spaces. Having social contact and support encouraged people to spend time outdoors. In the quantitative survey, self-report and standardised measures (the Patient Health Questionnaire and the Warwick-Edinburgh Wellbeing Scale) were used to assess past and current mental wellbeing. FINDINGS: Statistically significant differences were found between wellbeing and the use of green and blue spaces. Those with mental health problems spent time outdoors because they: felt guilty; wanted to reduce their anxiety; or rely on someone for encouragement. Those without mental health problems endorsed more positively framed reasons including relaxation, improving physical health or getting exercise. Barriers for people with mental health problems involved safety concerns, feeling anxious and having a poor self-image. These findings give insight into motivations for an outdoor activity to help inform the design of public mental health interventions. CONCLUSION: Further work is required to improve access and safety to promote the benefits of green and blue spaces for everyone. PATIENT OR PUBLIC CONTRIBUTION: The research team included expert experienced researchers with a mental health service provider (Praxis Care) and they were involved in the development of the research idea, funding application, design, data collection, analysis, writing up and dissemination activities.

Perceived and objective availability of green and blue spaces and quality of life in people with dementia: results from the IDEAL programme.

PURPOSE: The aim of this study was to investigate the associations between quality of life and both perceived and objective availability of local green and blue spaces in people with dementia, including potential variation across rural/urban settings and those with/without opportunities to go outdoors. METHODS: This study was based on 1540 community-dwelling people with dementia in the Improving the experience of Dementia and Enhancing Active Life (IDEAL) programme. Quality of life was measured by the Quality of Life in Alzheimer's Disease (QoL-AD) scale. A list of 12 types of green and blue spaces was used to measure perceived availability while objective availability was estimated using geographic information system data. Regression modelling was employed to investigate the associations of quality of life with perceived and objective availability of green and blue spaces, adjusting for individual factors and deprivation level. Interaction terms with rural/urban areas or opportunities to go outdoors were fitted to test whether the associations differed across these subgroups. RESULTS: Higher QoL-AD scores were associated with higher perceived availability of local green and blue spaces (0.82; 95% CI 0.06, 1.58) but not objective availability. The positive association between perceived availability and quality of life was stronger for urban (1.50; 95% CI 0.52, 2.48) than rural residents but did not differ between participants with and without opportunities to go outdoors. CONCLUSIONS: Only perceived availability was related to quality of life in people with dementia. Future research may investigate how people with dementia utilise green and blue spaces and improve dementia-friendliness of these spaces.

Physical, mental, and physiological health benefits of green and blue outdoor spaces among elderly people.

This study investigated the influence of designed natural outdoor spaces and space type on the physical, mental, and physiological health status of elderlies. A total of 978 questionnaires were distributed among a population-based randomized sample of elderlies residing in Bandar Abbas city, Iran. Blue space users reported better health status. Park access was associated with physical and physiological health. Those participants who had cardiovascular diseases were more likely to visit the parks more often, while the people with hypertension visited the parks less often. Length of park stay positively was associated with all aspects of health status. In addition, the level of physical activity positively was associated with physical and mental health. The park organizations should work on establishing parks in shorter distances and consider the opportunity for elderlies to participate in social programs to encourage them to frequently visit the parks and increase their length of park stay.

Blue space, health and well-being: A narrative overview and synthesis of potential benefits.

Research into the potential health and well-being benefits from exposure to green spaces such as parks and woodlands has led to the development of several frameworks linking the different strands of evidence. The current paper builds on these to provide a model of how exposure to aquatic environments, or blue spaces such as rivers, lakes and the coast, in particular, may benefit health and well-being. Although green and blue spaces share many commonalities, there are also important differences. Given the breadth of the research, spanning multiple disciplines and research methodologies, a narrative review approach was adopted which aimed to highlight key issues and processes rather than provide a definitive balance of evidence summary. Novel aspects of our framework included the inclusion of outcomes that are only indirectly good for health through being good for the environment, the addition of nature connectedness as both a trait and state, and feedback loops where actions/interventions to increase exposure are implemented. Limitations of the review and areas for future work, including the need to integrate potential benefits with potential risks, are discussed.

Physical and mental health effects of repeated short walks in a blue space environment: A randomised crossover study.

INTRODUCTION: Blue spaces may benefit mental health and promote physical activity, although the evidence is still scarce. And benefits on physical health are less consistent. The objective of this randomized crossover study was to assess psychological and cardiovascular responses to blue spaces' exposure. METHODS: A sample of 59 healthy adult office workers was randomly assigned to a different environment (i.e. blue space, urban space, and control site) on 4 days each week, for 3 weeks. For 20 min per day, they either walked along a blue or an urban space or rested at a control site. Before, during and/or after the exposure, we measured self-reported well-being and mood, blood pressure, and heart rate variability parameters. For well-being, we also assessed the duration of these potential effects over time (at least 4 h after exposure). RESULTS: We found significantly improved well-being and mood responses immediately after walking in the blue space compared with walking in the urban space or when resting in the control site. Cardiovascular responses showed increased activity of the sympathetic nervous system, both during and after walking along the blue and urban spaces. However, cardiovascular responses measured after the walks, showed no statistically significant differences between the blue and the urban space environments. CONCLUSIONS: Short walks in blue spaces can benefit both well-being and mood. However, we did not observe a positive effect of blue spaces for any of the cardiovascular outcomes assessed in this study.

Neighbourhood environment and dementia in older people from high-, middle- and low-income countries: results from two population-based cohort studies.

BACKGROUND: A growing number of studies have explored how features of the neighbourhood environment can be related to cognitive health in later life. Yet few have focused on low- and middle-income countries and compared the results across different settings. The aim of this study is to investigate the cross-sectional associations between neighbourhood amenities and dementia in older people from high-, middle- and low-income countries. METHODS: This study was based on two population-based cohort studies of people aged≥65: the Cognitive Function and Ageing Study II (CFAS II) in UK (N = 4955) and a subset of the 10/66 study in China, Dominican Republic and Mexico (N = 3386). In both cohorts, dementia was assessed using the Geriatric Mental State-Automated Geriatric Examination for Computer Assisted Taxonomy (GMS-AGECAT) algorithm. The 10/66 dementia diagnostic algorithm was also used as an additional criterion in the 10/66 study. Publicly accessible databases, Google Maps and Open Street Map, were used to obtain geographic information system data on distance to neighbourhood amenities, including lifestyle (cafés, libraries, movie theatres, parks), daily life (post offices, convenience stores), healthcare (hospitals, pharmacies) and percentages of local green and blue spaces within 400 and 800 m of participants' residences. Multilevel logistic regression was used to investigate the associations between these environmental features and dementia adjusting for sociodemographic factors and self-rated health. RESULTS: Living far from daily life amenities was associated with higher odds of dementia in both CFAS II (1.47; 95% CI: 0.96, 2.24) and the 10/66 study (1.53; 95% CI: 1.15, 2.04), while living far from lifestyle (1.50; 95% CI: 1.13, 1.99) and healthcare amenities (1.32; 95% CI: 0.93, 1.87) was associated with higher odds of dementia only in the 10/66 study. A high availability of local green and blue spaces was not associated with dementia in either cohort yet living far from public parks was associated with lower odds of dementia in CFAS II (0.64; 95% CI: 0.41, 1.00). CONCLUSIONS: The different relationships across cohorts may indicate a varying role for local amenities in diverse settings. Future research may investigate mechanisms related to these differences and social, cultural and historical influences on the interaction between neighbourhood amenities and older people.

Effects on general health associated with beach proximity in Barcelona (Spain).

Health benefits of blue spaces have been less studied compared with other urban natural environments. As a type of blue space, beaches are also affected by this lack of evidence, despite their cultural and economic importance in lots of coastal regions all over the world. Based on secondary health data from 3192 participants of the Health Survey of Barcelona 2016, we conducted a logit regression analysis to explore the relationship between people's general health and beach proximity from their dwelling place, controlling for several health determinants. Our main results suggested that having good general health was less likely for a 1-km increase in the linear distance to the closest beach from people's dwelling places (OR: 0.93; 95% CI: 0.87, 1.00). Moreover, the probability of having good general health was 45% higher for people living in the first 2 km from the beach (OR: 1.45; 95% CI: 1.01, 2.09), relative to those living >5-10 km from it. Also, these health effects were stronger for people with a low family income. These findings contribute to grow the currently small body of research related to health benefits of beach spaces. Likewise, they encourage fostering the use of these spaces for health promotion in cities, as well as protecting them and improving their accessibility and safety. Further research should lean towards the underlying causes of these health benefits linked to people's exposure to beach spaces.

Residential exposure to natural outdoor environments and general health among older adults in Shanghai, China.

BACKGROUND: Exposure to natural outdoor environments (NOE) has been shown to be beneficial to older adults' health and functioning, yet this assertion has rarely been tested in China. We investigated the relationships between exposure to NOE and older adults' self-rated health in Shanghai, China and examined whether these relationships varied by sex, age, education and hukou status. METHOD: This cross-sectional study used micro-data sample of the 2010 Shanghai population census, including 7962 older adults nested within 3345 neighbourhoods. Self-rated health was the outcome variable. Four NOE exposure indicators were calculated for each neighbourhood: the amount of surrounding greenness/blueness and proximity to large green/blue spaces. Multilevel logistic regression was employed to explore the association between natural outdoor environment exposure and self-rated health, adjusting for individual-level and neighbourhood-level covariates. Stratified analyses were used to examine variations by sex, age, education and hukou status. RESULTS: Older adults living in neighbourhoods with higher surrounding greenness and higher proximity to both green spaces and blue spaces were more likely to report good health. Residential surrounding blueness was not significantly related to self-rated health. Females, those aged 60-69 years, those who had elementary school or junior high school education and those with non-local hukou benefit more from residential surrounding greenness, and those aged 70-79 years and who had elementary school or junior high school education benefit more from residential proximity to blue spaces. CONCLUSIONS: Higher residential greenness and proximity to both green spaces and blue spaces were associated with better self-rated health, particularly for females, younger older adults, the low educated and non-local hukou holders. Our findings suggest that urban green spaces and urban blue spaces have different effects on health among Chinese older adults and that the assessment of exposure matters to the investigation of NOE-health relationships.

Long-term exposure to residential green and blue spaces and anxiety and depression in adults: A cross-sectional study.

BACKGROUND: Although exposure to natural outdoor environments has been consistently associated with improved perceived general health, available evidence on a protective association between this exposure and specific mental health disorders such as depression and anxiety is still limited. OBJECTIVE: The aim of this study was to evaluate the effects of long-term exposure to residential green and blue spaces on anxiety and depression and intake of related medication. Additionally, we aimed to explore potential mediators and effect modifiers of this association. METHODS: The study was based on an existing adult cohort (ALFA - Alzheimer and Families) and includes 958 adult participants from Barcelona recruited in 2013-2014. For each participant residential green and blue exposure indicators [surrounding greenness (NDVI), amount of green (land-cover) and access to major green spaces and blue spaces] were generated for different buffers (100m, 300m and 500m). Participants reported their history of doctor-diagnosed anxiety and depressive disorders and intake of related medication. Logistic regression models were applied to assess the corresponding associations. RESULTS: Increasing surrounding greenness was associated with reduced odds of self-reported history of benzodiazepines [e.g. Odds ratio - OR (95%CI) = 0.62 (0.43, 0.89) for 1-interquartile range (IQR) increase in NDVI in a 300m buffer] and access to major green spaces was associated with self-reported history of depression [OR (95%CI) = 0.18 (0.06, 0.58)]. No statistically significant associations were observed with blue spaces. Air pollution (between 0.8% and 29.6%) and noise (between 2.2% and 5.3%) mediated a proportion of the associations observed, whereas physical activity and social support played a minor role. CONCLUSION: Our findings suggest a potential protective role of green spaces on mental health (depression and anxiety) in adults, but further studies, especially longitudinal studies, are needed to provide further evidence of these benefits and of the mediation role of exposures like air pollution and noise.

[Contribution of natural spaces to human health and wellbeing]. / Einfluss von Naturräumen auf die Gesundheit ­ Evidenzlage und Konsequenzen für Wissenschaft und Praxis.

Natural spaces and especially urban green and blue spaces have been recognised for a long time as spaces with great potential for protecting and promoting human health and well-being. They may affect human physical, mental and social health and well-being in various ways. On one hand, this comes to pass through reduction and moderation of potential environmental health risks (e. g. noise, particulate matter, heat), psycho-physiological effects of nature experience, as well as physical effects of exposure to natural compounds and elements. On the other hand, natural spaces can affect health and well-being indirectly e. g. through motivation of health promoting behaviour (e. g. more physical activity) and through use as outdoor meeting spaces, by decreasing aggression, and through the resulting positive effects on social well-being. Yet, some potential adverse health effects of nature and landscapes have been reported, too (e. g. insecurity or fear in confusing or unmaintained natural spaces, potential rivalry in usage, allergies or skin irritations due to natural elements, risk of communicable diseases from vectors). Against the background of positive effects of natural spaces, creating, restoring and enhancing urban green and blue spaces are often claimed in terms of sustainable and integrated urban development. But which associations and impacts exist between natural spaces and health? What are the resulting demands when integrating natural spaces for a health-promoting implementation practice? This overview article provides some answers to these questions.

Swimming, confusion, and plenty of brews: Negotiating ambivalence within Windermere's fragile waters.

Windermere is a complex and contested freshwater site which encounters fluctuating social and environmental pressures. Swimmers at Windermere regularly practice across all four seasons while negotiating social concerns such as access, conflicting user groups, public health communications, and swim safety, alongside environmental complications including extreme weather, wastewater, run-off, plastic pollution, algal blooms, biosecurity, and climate change. Simultaneously, these entangled pressures generate ongoing adaptation, ambivalence, and avoidance within the swim communities. Furthermore, they disrupt individualised and inwardly focused understandings of 'healthy' outdoor swimming practices. In contribution to the special issue (on outdoor swimming), this article reflects on how outdoor swimming researchers may methodologically attend to these social and environmental complexities within contested lacustrine environments through an immersive 12-month wet ethnographic approach, combining 'lake-hangouts' and 'swim-along interviews' with different swimmers at Windermere. The article discusses how these relational in-situ approaches can continue to broaden inwardly focused understandings of 'healthy' outdoor swimming practices towards the wider social and environmental relations for both the participants and researcher. The article also highlights senses of ambivalence and ethical tension while negotiating conflicting concerns of ill-health, in and out of Windermere's fragile waters.

The impact of outdoor blue spaces on the health of the elderly: A systematic review.

Research on natural health has identified the potential benefit of outdoor blue spaces for human health and wellbeing. However, the existing evidence has relatively limited attention to the elderly. This study aims to review the available evidence on outdoor blue spaces and health outcomes among older individuals and identify knowledge gaps. In accordance with the PRISMA guidelines, specific keywords were used to search for articles published in English from inception to October 2023. Five databases (Scopus, PubMed, Web of Science, CINAHL, and PsycINFO) were searched, and 22 studies were identified in this review. We classified articles based on elderly health as general health (e.g., self-reported, perceived health and wellbeing), physical health (e.g., physical activity, physical function index), and mental health and wellbeing (e.g., depression). The findings indicated a positive correlation between outdoor blue space and the health of the elderly. In terms of the characteristics of exposure to outdoor blue spaces, direct contact (e.g., sensory-based) has not been well documented compared to indirect contact (e.g., distance, percentage, region-based). Although encouraging, the available body of evidence is limited and lacks consistency. Future research is needed to provide complementary evidence between outdoor blue spaces and elderly health.

Greenspaces and Health: Scoping Review of studies in Europe.

Objectives: Access to greenspaces and contact with nature can promote physical activity and have positive effects on physical and mental health. This scoping literature review aims to examine current evidence linking greenspaces and (a) behaviour change, (b) health outcomes and (c) co-benefits. Methods: This review was conducted in accordance with the PRISMA scoping review guidelines. Searches were conducted through PubMed and EMBASE databases for studies published between 2000 and March 2023 with a focus on Europe. Results: 122 scientific articles and grey literature reports were identified. Access to greenspaces is positively associated with physical and mental health, and reduced risk of all-cause mortality and some non-communicable diseases. Greenspace quality is associated with increased physical activity and reduced risk of obesity. Nature-based therapies or green prescription are effective in improving mental health outcomes and overall health. Importantly, numerous co-benefits of greenspaces are identified. Conclusion: Increasing access to greenspaces for populations with particular attention to greenspace quality is important for co-benefits. Responsible governance and use of greenspaces are crucial to minimize public health risks and human disturbance of nature.

Hydrophobia, dis/connection, and difference: Understanding Chinese immigrants' fear of coastal swimming in Aotearoa New Zealand.

New Zealand's coastal blue spaces, from harbours to beaches, provide diverse wellbeing benefits but can also be sites of danger, fear, and cultural contestation. This qualitative research focuses on Chinese migrants in Auckland, a community who are underrepresented in coastal recreation and overrepresented in drowning statistics. Findings show Chinese migrants dis/connection with coastal blue space and fear of coastal swimming, derived from their homeland habitus and lack of coastal 'blue space' cultural capital. Our research contributes to the growing recognition of 'hydrophobia', and how the racialisation of leisure space impacts the potential for blue spaces and practices to be therapeutic.

Adventure Recreation in Blue Spaces and the Wellbeing of Young Polish Adults.

The aim of this study was to assess the wellbeing of 248 young Polish adults between 18 and 26 years old (M = 22.35; SD = 2.20) involved in adventure blue space recreational activities. The adventure water recreational activities were measured by using a questionnaire specially designed for the purpose of this study. This questionnaire consisted of two subscales: adventure recreation associated with water risks and adventure recreation associated with weather risks. In turn, wellbeing was measured using six scales loaded in two factors: hedonic wellbeing and eudaimonic wellbeing. The regression analysis indicated that wellbeing (hedonic and eudaimonic) was positively predicted by adventure recreation associated with water risks. In turn, eudaimonic wellbeing was negatively predicted by adventure recreation associated with weather risks. Additionally, the cluster analysis revealed three distinct clusters of recreationists characterized by diverse results on the scales of adventure recreation dealing with water and weather risks: soft adventurers (low water risks/high weather risks), hard adventurers (high water risks/high water risks) and avoiders (low water risks/low weather risks). The hard adventurers had significantly higher means on hedonic wellbeing than that of the soft adventurers and the avoiders. Surprisingly, the soft adventurers had a significantly lower mean on eudaimonic wellbeing than that of the group of hard adventurers and the group avoiding risky activity in an aquatic environment.

Associations of green and blue space exposure in pregnancy with epigenetic gestational age acceleration.

Early life is seen as a particularly sensitive period for environmental exposures. Natural space exposure during pregnancy has been associated with offspring health. Epigenetic gestational age acceleration, a discrepancy between clinical and DNA methylation-based gestational age, may underlie these associations. In 1359 mother-newborn pairs from the population-based Generation R Study, we examined the associations of natural space exposure, defined as surrounding greenness, distance to major green and blue (water) space, and size of the blue space during pregnancy with offspring epigenetic gestational age acceleration. Natural space exposure was based on participants' geocoded addresses, and epigenetic gestational age acceleration was calculated from cord blood DNA methylation using Bohlin's and Knight's epigenetic clocks. Sensitivity analyses were conducted in a subgroup of newborns with optimal pregnancy dating, based on last menstrual period. Surrounding greenness, measured in normalized difference vegetation index values, was intermediate (median 0.4, IQR 0.2), and 84% and 56% of the participants had a major green or blue space near their home address, respectively. We did not observe associations of natural space availability during pregnancy with offspring epigenetic gestational age acceleration. This could imply that epigenetic gestational age acceleration in cord blood does not underlie the effects of residential natural space availability in pregnancy on offspring health. Future studies could investigate whether residential natural space availability during pregnancy is associated with offspring differential DNA methylation at other CpGs than those included in the epigenetic gestational clocks.

Amount of and proximity to blue spaces and general health among older Chinese adults in private and public housing: A national population study.

A growing body of research indicates that exposure to outdoor blue spaces is associated with better physical and mental health. However, few studies have explored the associations between different blue space indicators (e.g., amount of and proximity to freshwater and seawater) and general health. Moreover, research has rarely attempted to address the residential selection bias associated with the salutogenic effect of access to blue spaces. Therefore, this study explores the associations between the amount (percentage of blue space within a 1 km circular buffer) of and proximity (Euclidean distance to the edge of the nearest blue space) to blue space and older adults' general health across the entire country of China using the micro-data sample of one-percent national population sample survey in 2015. It adds to the existing literature by taking into account the neighbourhood selection mechanism for different housing tenures and examining the salutogenic effect of blue spaces separately for public housing residents and private housing residents. The results indicated that greater neighbourhood seawater coverage and living near a coastline were associated with better general health among older adults in both private and public housing, while the percentage of freshwater blue spaces within neighbourhoods and the distance to freshwater blue spaces were associated with better general health among private housing residents only. The blue spaces-general health associations were stronger among urban participants, participants in deprived neighbourhoods, males, participants aged under 80 years, and low- and medium-educated participants. Our findings indicated that living near the coast was beneficial to older adults' health, and residential selection bias confounded the association between freshwater blue spaces and health.

Exploring Blue Spaces' Effects on Childhood Leukaemia Incidence: A Population-Based Case-Control Study in Spain.

BACKGROUND: Blue spaces have been a key part of human evolution, providing resources and helping economies develop. To date, no studies have been carried out to explore how they may be linked to paediatric oncological diseases. OBJECTIVES: To explore the possible relationship of residential proximity to natural and urban blue spaces on childhood leukaemia. METHODS: A population-based case-control study was conducted in four regions of Spain across the period 2000-2018. A total of 936 incident cases and 5616 controls were included, individually matched by sex, year of birth and place of residence. An exposure proxy with four distances (250 m, 500 m, 750 m, and 1 km) to blue spaces was built using the geographical coordinates of the participants' home residences. Odds ratios (ORs) and 95% confidence intervals (95%CIs) for blue-space exposure were calculated for overall childhood leukaemia, and the acute lymphoblastic (ALL) and acute myeloblastic leukaemia (AML) subtypes, with adjustment for socio-demographic and environmental covariates. RESULTS: A decrease in overall childhood leukaemia and ALL-subtype incidence was found as we came nearer to children's places of residence, showing, for the study as a whole, a reduced incidence at 250 m (odds ratio (OR) = 0.77; 95%CI = 0.60-0.97), 500 m (OR = 0.78; 95%CI = 0.65-0.93), 750 m (OR = 0.80; 95%CI = 0.69-0.93), and 1000 m (OR = 0.84; 95%CI = 0.72-0.97). AML model results showed an increasing incidence at closest to subjects' homes (OR at 250m = 1.06; 95%CI=0.63-1.71). CONCLUSIONS: Our results suggest a possible association between lower childhood leukaemia incidence and blue-space proximity. This study is a first approach to blue spaces' possible effects on childhood leukaemia incidence; consequently, it is necessary to continue studying these spaces-while taking into account more individualised data and other possible environmental risk factors.