Loneliness is increasingly recognized as a significant public health concern, leading some to describe it as an epidemic. (Ng, 2024; Powell, 2024). It is associated with various physical and mental health issues, including cardiovascular disease, depression, and cognitive decline (Holt-Lunstad, 2017; Alun and Murphy, 2019) and affects people across all age groups and socioeconomic backgrounds, with prevalence rates rising over time (Buecker et al., 2021b).

Loneliness is defined as a complex and subjective experience characterized by a perceived deficiency in social relationships, which can occur even in the presence of others (Perlman and Peplau, 1981; Cantor, 2020). This distressing feeling arises from discrepancies between desired and actual social connections (Alspach, 2013; Yang and Gu, 2020). The COVID-19 pandemic together with the increasing numbers of extreme climate events has exacerbated the loneliness epidemic, with prolonged social distancing measures and stay-at-home strategies leading to social isolation and the breakdown of social connections (Trad et al., 2020; Hartt, 2021; Lai, 2023). Given its significant impact on health and well-being and the increasingly frequent abovementioned events, loneliness is now considered a significant health risk associated with spatial isolation, requiring attention from multi-disciplinary researchers, healthcare professionals and policymakers (Lederman, 2021; Ng, 2024). Various interventions, including spatial intervention policies, cognitive-behavioral therapy, social skills training, and community programs, are required to address this issue (Ng, 2024).

Existing evidence suggests that the physical environment (i.e., the natural and built environment) significantly influences loneliness. Compact neighborhoods with higher density, mixed land uses, and access to green spaces are associated with lower levels of loneliness (Lam and Wang, 2022). Walkability, local resources, and transportation alternatives can also help to address loneliness (Lyu and Forsyth, 2022). Increased greenness was found to be linked to lower loneliness and social isolation, particularly among older adults and those living alone (Astell-Burt et al., 2022a; Villeneuve et al., 2024; Wang et al., 2024). Some studies have delved into the moderation mechanisms by which green spaces affect loneliness. The relationship between greenness and mental health may be mediated by factors such as physical activity, stress reduction, improved air quality, and social cohesion (Wang et al., 2019). Additionally, greener neighborhoods were associated with higher neighborhood satisfaction and social capital (Orban et al., 2017), which serve as protective factors for loneliness. These findings indicate how environmental factors may influence loneliness through the interactions between people and the environment. Two theories at the intersection of sociology and geography offer valuable insights into human-environment interactions and loneliness. Rooted in humanistic geography (Tuan, 1977), Place Attachment Theory describes the emotional and affective bonds people develop with meaningful places. This theory provides a foundation for understanding loneliness by proposing that a strong attachment to one's environment fosters a sense of security and belonging, which counteracts feelings of social isolation. As an extension of Gibson's (2014) work, Socio-environmental Affordance Theory posits that physical environments contain properties or 'affordances' that signal and facilitate specific social behaviors. Thus, it provides a basis for loneliness by suggesting that environments rich in social affordances (i.e., public seating) enable the interactions that build social connection, while environments lacking these features create barriers to social engagement. Studies on merely objective environmental characteristics are insufficient to capture these interactions and reveal the underlying reasons behind this influence.

The impacts of subjective environmental perception, engagement and interaction on loneliness are increasingly gaining attention among researchers. Positive perceptions of neighborhood quality, safety, and collective efficacy are linked to reduced loneliness (Kearns et al., 2015; Domènech-Abella et al., 2020). The presence of green views from home and frequent use of green spaces are associated with improved mental health outcomes (Soga et al., 2021). Interactions with green spaces can increase feelings of connectedness, self-esteem, and happiness while decreasing depression, anxiety, and loneliness (Soga et al., 2021; van Houwelingen-Snippe et al., 2020), especially as parts of group interactions. Group-based nature activities have demonstrated effectiveness in addressing loneliness by fostering social connections and a sense of belonging (Vitalia, 2020; Sachs et al., 2024). However, these types of studies are modest in number and scope, and researchers emphasize the need for more comprehensive studies incorporating different types of spaces, loneliness measures, and longitudinal effects across different cultural settings (Astell-Burt et al., 2022b). Nature prescriptions and interventions to address loneliness should consider individual motivations and barriers to ensure effectiveness and sustainability (Astell-Burt et al., 2023), which are also associated with cultural backgrounds.

Research indicates that loneliness varies across cultures. Loneliness is influenced by macro-level factors such as cultural ideology, values, and norms (Luhmann et al., 2023). Individualistic societies tend to report higher levels of loneliness compared to collectivistic ones (Lykes and Kemmelmeier, 2014; Barreto et al., 2021). The absence of family interactions is more strongly linked to loneliness in collectivistic societies, while the lack of friendships and confidants is more impactful in individualistic cultures (Lykes and Kemmelmeier, 2014). Cultural norms shape expectations of social connectedness and influence the perception of the causes of loneliness (Rokach and Bacanli, 2001; van Staden and Coetzee, 2010). Deviations from social norms can increase loneliness risk across cultures (Heu, 2025). Restrictive cultural norms may protect against physical isolation but increase emotional and perceived isolation (Heu et al., 2021a, 2021b).

Some of the existing cross-cultural studies reveal differences in loneliness levels associated with variations across locations due to the sense of power mediated by perceived self-construal and social support (Cai et al., 2023). Meanwhile, environmental and individual factors contribute to regional differences in loneliness. A loneliness study in Germany, for example, found that the differences in loneliness levels between East and West Germany were partly attributable to the compactness of settlement structures and regional remoteness (i.e., distances to regional centers). At the individual level, demographic features, socioeconomic status, and social relationships are all significant factors influencing loneliness (Buecker et al., 2021a). However, there are currently few articles comparing the impact of environmental factors on loneliness in different cultural contexts, let alone demonstrating how and why these impacts may vary across cultures.

The physical environment's influence on loneliness is multi-faceted and complicated, in which cultural factors are a significant moderator. Neighborhood green spaces and parks may reduce loneliness risk in middle-aged and older adults, partially mediated by social cohesion and reciprocity norms (Fu et al., 2024; Su et al., 2024; Wang et al., 2024). The impact of green spaces on loneliness is influenced by cultural beliefs about reverence for or proximity to nature, as well as the importance placed on community and collective activities and interactions. As for the built environment, the availability and proximity of recreational facilities, health care services, and transportation networks in compact neighborhoods with mixed land use are negatively correlated with loneliness (Lam and Wang, 2022; Fu et al., 2024). This finding suggests that access to various destinations may improve social interactions, employment, and recreational opportunities and reduce feelings of isolation. However, shopping facilities and the land-use mix surrounding university campuses are positively correlated with loneliness among Chinese university students (Deng et al., 2025). While shopping can provide an opportunity for leisure activities and temporarily place oneself in a lively setting with customers and shopkeepers, shopping as a form of emotional compensation may lead to anxiety and shame, particularly among financially dependent students who were raised in a culture of thrift and self-sufficiency. On the one hand, a diverse land-use mix can promote social interactions, but on the other hand, it could cause sensory overload for academic-focused students and exacerbate their fatigue, anxiety, and isolation. Cultural factors play a crucial role in shaping the complex interplay between the physical environment and loneliness, but no studies to date have focused on these relationships.

This review was built on earlier reviews by Astell-Burt et al. (2022b), which explored the relationships between green space and loneliness, and Bower et al. (2023) who examined the impact of the built environment on loneliness. We set out to explore the connections linking the built environment, green spaces and loneliness, thinking that the characteristics of the built environment and nearby green spaces might exacerbate the negative outcomes that accompany loneliness in some instances and that the individual characteristics of either the built environment or green spaces might offset some of the outcomes that accompany loneliness in other cases. A third review by Schepers et al. (2025), which covered the relationships between physical and social neighborhood characteristics and loneliness, found the significance of subjective experiences in shaping these relationships, and advocated for further research to explore the complex interrelations.

One immediate difference between this review and the previous ones is the choice of methodology. We chose to use a scoping review methodology whereas they all applied a systematic review methodology. We chose the scoping review methodology because the literature on the interactions between cultural and physical environment and their influences on loneliness remains limited. Although existing studies cover diverse cultural, spatial, and demographic settings, they are few in number and have adopted different measures of key concepts, such as loneliness and cultural factors, which hinders quantitative comparison across studies.

To address the existing research gap, this study conducts a literature review on physical environments and loneliness globally, hoping to address two questions: 1) How does the urban physical environment impact loneliness, and how do these impacts vary across cultures? 2) How might our existing knowledge of environmental impacts on loneliness across cultures impact the efficacy of spatially driven interventions and policies designed to reduce loneliness?