Defining Urban Health for Strategic Action

Key elements

Below we highlight the rationale and implications of specific elements of the proposed definition. By clarifying the emphasis and meaning of these elements, we intend to provide a deeper understanding of the definition itself and to inform its translation into other languages.

“Urban health ”

“… 1 the art and science …”

“… of improving health and health equity … every person …”

“… securing resilience and sustainability …”

“… of health-supporting natural and human systems.”

“More than the sum of its parts …”

“… to create healthy situations and … the chance to thrive …”

“… now and into the future …”

“… 2. a measure of the health of urban dwellers …”

“… as continually created …”

“… by their complex interactions …”

“… with urban physical and social environments …”

“… and by the decisions and institutions … that shape these interactions …”

With this definition in mind, we explore several key aspects of urban health in further detail.

What is urban?

Given that urban health deals with the health of urban dwellers, the definition of urban is key to understanding its scope and possibilities, yet there is no universally accepted standard, and finding common ground has posed an ongoing challenge (Dijkstra et al., 2021; Iossifova et al., 2017). Variable definitions of urban likewise make the identification of urban dwellers less than straightforward.

There is a consensus that urban areas, broadly, are characterized by large, dense populations and concentrations of anthropogenic institutions, infrastructure, goods, and services.¹ Yet in deciding whether a particular place is urban, different arbiters emphasize different aspects of urbanicity. These may include population size or density, political status or jurisdictional considerations, the typical occupation of residents or other economic indicators, assessments of infrastructure, or other social or cultural phenomena (Iossifova et al., 2017; Ritchie et al., 2024).

Based on similar considerations, a multitude of terms has also arisen to describe different types of urban areas, urban features, or varying levels of “urbanicity.” For example, the idea of “settlement hierarchies”, which characterize human settlements along a continuum of size, status, or other features has arisen in various historical contexts, and was propounded more formally by Doxiadis (1970) and others. However, this and other urban-related terms can also have different definitions and usages. While a full discussion of urban terminology is beyond the scope of this paper, resources such as the Multilingual Glossary of Human Settlements Terms developed by UN-Habitat can provide useful context (UN-Habitat, 1992).

One important distinction is between the terms “urban area” and “city”, which are sometimes conflated. A “city” is typically defined in political or administrative terms, referring to an area governed by a local authority with the power to create, manage, and enforce rules. In contrast, an “urban area” is a geographical term defined by the presence or absence of typical urban features or characteristics. Cities and urban areas don’t always align; many urban regions extend beyond city boundaries, and some span multiple city jurisdictions (Duminy et al., 2023). Metropolitan areas often incorporate smaller cities along with multiple layers of governance. Additionally, some cities include rural areas within their political boundaries.

Global assessments of urbanization typically adopt national definitions, which may differ enormously from country to country and can create inconsistent categories. For example, “Sweden and Denmark set [the] threshold [for defining urban areas] at only 200 inhabitants; Japan at 50,000 (a 250-fold difference)” (Ritchie et al., 2024). Where classification is based on a city’s political status or other considerations not related to its constituent features, definitions can lead to different “urban” areas having significant qualitative differences, or to the exclusion of areas with urban qualities.

Efforts have also been made to produce more universal, replicable, and globally comparable definitions of urban using satellite imagery and gridded population data. For example, the Degree of Urbanization (DEGURBA), has been endorsed by the UN Statistical Commission (UN Statistical Commission, 2020). It applies universal criteria based on gridded density and total population thresholds to determine what areas are urban. DEGURBA estimates substantially higher urbanization than traditional assessments based on national definitions, especially for Africa and Asia (Dijkstra et al., 2021).

Different disciplinary traditions may also apply different definitions of urban, focusing on the processes and features most relevant to their disciplinary fields and research paradigms (i.e., in academia) or sectoral responsibilities (i.e., in practice); such definitions are strongly influenced by the historical development of the discipline in question (Wolman et al., 2024).

There is significant value in specialized national and disciplinary definitions of urban. The former may yield insights more relevant to local conditions; the latter may lend themselves more readily to generating relevant research questions or policy formulations. Yet different definitions may also lead to misclassification, misinterpretation, and miscommunication, and therefore to incompatibilities or a lack of generalizability in data or the insights derived therefrom and to conflicts or inefficiencies among actions taken in consequence.

The way that urban is defined in the context of urban health practice must be guided by objectives. Where the goal is to design or evaluate urban health action for a particular place, traditional (i.e., national) definitions may better capture the local governance context and its impacts. Where comparison or generalizable insights are intended, universalized definitions like the Degree of Urbanization likely offer a more useful, harmonized approach. In any case, awareness of the differences between definitions (including nationally vs. globally defined and disciplinary/sectoral) and their implications will lead to more comparable, generalizable insights, better communication, and more effective action.

Health impacts beyond urban areas

Although we restrict urban health to urban dwellers, actions taken in and for urban areas do have health impacts well beyond their boundaries, given the magnitude of urban processes and cities’ prominence in local, regional, and global systems.

There are at least six categories of such extramural effects, including health impacts from:

Exposures and outcomes for the first five types occur in urban or rural areas that are separated—sometimes at great distances—from their source. While it is therefore challenging to include these influences in city-level urban health action, awareness of extra-urban impacts can help urban health actors make decisions that improve health more broadly and avoid decisions that harm health outside of their cities. National-level strategic action is better positioned to address specific extra-urban impacts and may incorporate such processes into the remit of urban health authorities.

In contrast, the final type of impact involves exposures within urban boundaries and is more amenable to city-level action—thus the inclusion of temporary “dwellers” among the subjects of urban health.

Including all urban dwellers: urban health equity

Urban areas are, on average, healthier than rural areas, yet are also home to enormous disparities in health and in the determinants of health. Slums and informal settlements experience some of the worst health outcomes (WHO and UN-Habitat, 2010) and house about a quarter of the urban population globally; this proportion has been decreasing while the absolute number of slum dwellers continues to rise (Ritchie et al., 2024). Despite their ubiquity, slums and informal settlements are often left behind in urban policies and priorities.

As outlined above, an equity focus is critical to any complete definition of urban health and its subjects. Health inequities, by definition, arise from modifiable factors; they are rooted in the social determinants of health, in many contexts reflect historical inequities in decision-making or contemporary stigma, and are often expressed in well-defined spatial patterns.

Redressing such inequities requires not solely an effective overall approach to urban health, but also targeted efforts to reduce disparities and reverse the conditions which generate them (Lee et al., 2023). In general, this requires action on both the upstream, structural determinants of health, such as governance, culture, and social and public policies, and more proximal, intermediary determinants, like material circumstances and behaviors (Solar and Irwin, 2010).

Including urban dwellers everywhere: urban health geography

Urban health is important and becoming more so in all geographical regions. Indeed, the range of environmental, social, and economic factors at play across different geographical contexts demands the application of diverse perspectives to the practice of urban health. However, urban health thought leadership, narratives, data, and guidance are unequally distributed; these resources are more readily available in the Global North, Western cultures, and larger, wealthier, more prominent cities (e.g., megacities) (Taylor et al., 2018). This is especially challenging because the preponderance of urbanization is taking place in the Global South and in small- to medium-sized cities, under far different conditions than in previous growth centers.

To support strategic action, a universal definition must span cultural and communicational differences—and must be available in local languages. However, the diversity of language challenges universality, as different language traditions have different cultural signifiers, content, norms, and value structures. Some concepts are essentially untranslatable, and it is not possible to create a definition that transmits precisely the same information and connotations across all languages. Nevertheless, we attempt to convey the essential messages of the proposed definition through suggested translations into the six languages of the United Nations (see Box 1). We welcome constructive debate to improve the accuracy of these translations, and we encourage translation of the definition into additional languages.²

Urban health beyond human health

Although human health is the end point for urban health practice and its subjects are human beings, there are good reasons for it to consider the health of other organisms and ecosystems, both those in urban areas and those beyond their boundaries that are affected by urban processes. Attention to the health of ecosystems and non-human organisms is critical to achieving human health in urban areas. Ecosystems affect urban health via an extensive range of causal pathways, including those that are environmental (e.g., regulation of microclimate, air quality, or flood risk), ecological (e.g., pollination impacts on agriculture, infectious disease transmission), physiological (e.g., microbial impacts on immune function), or social (e.g., influence on opportunities for recreation and social bonding) in nature. These dynamics and connections are recognized by One Health and related rubrics (see below) and in the definition presented here.

The nature of urban health challenges

Urban areas concentrate people, institutions, infrastructure, goods, and services, and anchor long distance processes like migration, trade, knowledge diffusion, and communications. This density underpins complex interactions among all these factors and with local environments. Moreover, just as every action has economic implications (i.e., costs or benefits, including opportunity costs), every action also has health implications. As such, the panoply of actors and institutions—spanning all sectors and scales—that influence the urban milieu are also contributing to urban health, interacting in complex ways to produce outcomes.

While a technical discussion of urban complexity is beyond the scope of this paper, certain aspects of the dynamics of urban systems have critical implications for urban health. For example:

This complexity can lead to unpredictable outcomes, low or diminishing effectiveness or efficiency of interventions, and undesirable patterns of behavior, including boom-bust cycles, escalating problems, or collapse.

Grappling with complexity and grasping its potential impacts is essential to navigating potential actions and managing its consequences. Conversely, a failure to engage with complexity can lead to policy failures (Newell and Siri, 2016). As such, recognition of complex interactions is essential to strategic action, as recognized in the definition presented here.

Who is responsible for urban health action?

We distinguish between causal responsibility and institutional responsibility—the former is descriptive; the latter is prescriptive.

All urban stakeholders’ actions have health consequences, and therefore all have some level of causal responsibility for urban health. Typically, urban health outcomes result from competing causal pathways that are difficult to fully visualize or disentangle, making it challenging to attribute responsibility to specific actions or actors—although actions with outcomes that are more proximate or of greater magnitude are easier to characterize. Analyzing, documenting, and educating about the impact of different actors’ decisions on health is an important part of moving beyond siloed practice.

In the institutional sense, responsibility for urban health is generally delegated to relevant authoritative bodies. In the absence of specific guidance, formal institutional authority is likely to devolve to the health sector as an aspect of public health. The health sector is indeed the primary actor charged with securing and improving health. It also has a duty to inform, illuminate causal pathways, and make all stakeholders more aware of their health impacts. Yet in the face of urban complexity, it is crucial that urban health activity not be constrained to health sector interventions.

In some contexts, the leadership role or locus of control for urban health is allocated to other sectors or to cross-sectoral bodies. This may reflect resource considerations; cultural preferences; the distribution and relationships of local determinants, health outcomes, or stakeholders; or other factors. Although comprehensive plans are rare, cross-sectoral urban health leadership is emerging for some issues. For example, the need to address urban heat-health risks is spurring cities around the world to experiment with cross-sectoral institutional mechanisms—like chief heat officers, tasked with “delivering a unified response to extreme heat … coordinating dispersed efforts both inside city government and across the private sector … [and] break [ing] down silos” (Atlantic Council Climate Resilience Center, 2024).

The nature of specific urban health challenges may also suggest—or even dictate—a particular authority structure. Some issues have relatively straightforward, well-understood solutions without strong systemic ramifications that are easily managed by specific sectors or stakeholders. Identifying such issues is an important part of efficient strategic urban health action.

No single locus or form of authority structure is ideal for urban health in all contexts, and the best arrangements will depend on local conditions. But purposeful allocation of authority is a critical aspect of urban health action (WHO, 2023a).

Regardless of how authority is allocated, the practice of urban health necessarily transcends the boundaries of the health sector (see Figure 1 for examples). Traditionally, several specific sectors are associated with and often bear some level of (causal and/or institutional) responsibility for urban health, due to strong, direct, and/or highly visible associations. For example:

Similarly, urban health is dependent on actions at multiple scales, implicating actors at these levels with some level of responsibility for outcomes. For example:

Lastly, urban health depends on action across a range of domains:

The ecumenical nature of responsibility for urban health implies that a common definition should be agnostic about the range or precedence of protagonists. Formal authorities and processes for urban health will be defined locally, yet any actor that ensures the existence of healthy situations and opportunities and/or the resilience and sustainability of health-supporting systems is practicing urban health.

What is the scope of urban health action?

It is difficult to place conceptual or practical boundaries on urban health, in part because urban systems are extensively interlinked. Every action has both immediate and downstream consequences, and every outcome has both immediate and upstream causes. Likewise, all actions have multiple outcomes, and all outcomes have composite causes.

Not having a clear sense of the level or types of actions that should be included makes it difficult to estimate the potential impacts or benefits of urban health action (Garber et al., 2024). For example, while most arbiters would agree that designating cycle lanes falls under the aegis of urban health, it is less clear whether this is true for implementing 15-minute-city strategies that envision a wholesale redesign of the urban fabric—the latter may be seen as beyond the remit of urban health, despite having profound health implications. In the same vein, where should formal urban health strategies draw the line insofar as the actions they consider?

Important questions about remit include:

While the answers are not cut-and-dried, the definition proposed here suggests a qualified “yes” to each of the previous questions, in conceptual terms.

However, the formal scope of urban health action will vary with different political and institutional contexts and across cities and countries with different risk profiles and resource pools. Three factors tend to determine the definition of formal limits to urban health action in a particular context:

Where resources (e.g., financial, human, institutional) are plentiful, the scope of formal urban health action is more likely to be able to encompass determinants that operate less directly or have a lower magnitude of impacts. Where resources are scarce, the focus is likely—unfortunately—to be restricted to the most direct, highest magnitude determinants, even though many upstream determinants have extensive impacts on a range of health outcomes.

We stress that this is a descriptive, not a normative, analysis. As a matter of equity, everyone should enjoy access to the highest attainable standards of health, which implies addressing all significant risk factors. Increasing the efficiency or effectiveness of urban health action through strategic approaches allows for the expansion of the horizon of potential action. Meanwhile, assuring the availability of financial and human resources for urban health practice at a level consistent with strategic action is a critical function of governance for urban health (WHO, 2023a).

In general, urban health action should:

Because all actions that impact urban phenomena have health implications, there is no theoretical limit to the set of activities that could be incorporated under the rubric of urban health. Practically, however, the scope of formal urban health action should not exceed the point where the marginal costs (e.g., of coordinating mechanisms, interventions) exceed the marginal benefits. This limit may not be possible to measure directly, but it can serve as a guiding principle.

In defining the scope of urban health action, decision-makers should consider a range of potential intervention points, including:

The nature of urban health solutions and the need for a strategic approach

Even though all urban actions affect health, urban health interventions are often circumscribed, siloed, and fragmented from one another and tend to focus on limited sets of outcomes, sectors, determinants, or targets.

Such isolated actions can have positive effects in some contexts. Moreover, not every action has significant systemic impacts, and some urban health challenges can be managed straightforwardly by specific sectors or stakeholders. Identifying such situations is an important aspect of urban health.

Nevertheless, a long history of intellectual and programmatic work has recognized the need for cross-cutting action. For example, it is central to the Healthy Cities and Health in all Policies (The Helsinki Statement on Health in All Policies, 2014) approaches.

To be optimally effective, urban health must go beyond expanding the range of sectors that implement health-oriented actions and adopt a strategic approach (see Box 2), linking actions across sectors, scales, and domains in a coherent strategy that considers how complexity will affect outcomes over time (WHO, 2024a, 2024b, 2024c, 2023a, 2023b). The definition proposed here is intended to support the adoption, implementation, and political prioritization of a strategic approach to urban health.

How does urban health relate to other rubrics?

Long-standing fields such as public health/healthcare and Healthy Cities share epistemic roots and thematic foundations with urban health. Likewise, in recent decades, several rubrics that encompass similar themes have grown in prominence—these include resilience, planetary health, One Health, and ecohealth. Given broad overlap among all of these with respect to subject matter and practical remit, proponents of a specific approach sometimes claim primacy or exclusivity. These arbiters may see competing rubrics as secondary, redundant, or even counterproductive. However, despite the potential for many of these broad topics to cover similar ground, there are important differences in how they are perceived and applied, which make them valuable complementary perspectives for urban health, rather than competitors. We review a few important distinctions below.

Urban health versus public health/healthcare

Public health and urban health have similar goals. Both seek to improve the health of populations and recognize a wide range of determinants. Depending on terminological assumptions, each could plausibly be considered an important subcomponent of the other. However, as defined here, urban health is not merely the aspect of public health that deals with urban dwellers.

In institutional terms, public health is generally a subdivision of the health sector, whereas urban health, as outlined above, is broader, spanning the boundaries of many sectors. Urban health calls on the service of a broad range of urban experts and actors, and not solely on health actors or other elements of the health sector in urban environments. Urban health likewise covers a wider range of determinants and activities than is usually the case in public health.

Conversely, urban health does not necessarily cover every aspect of health in urban populations. Some outcomes are unrelated to urban determinants. For example, for genetic or age-related illnesses, the context is generally coincidental rather than determinative. Urban health, as defined here, deals with impacts arising from causal pathways specific to urban areas. Yet even health issues without clear urban determinants interact with urban phenomena (e.g., health systems; environmental, economic, social, and commercial determinants) to modulate outcomes when they occur in cities. To extend the example above, genetic and age-related illnesses both interact with urban contextual factors, and this interaction is a proper focus for urban health action.

One practical concern about subsuming urban health within traditional public health is an overemphasis on health sector-led action. Healthcare systems are but one among many key determinants of health for urban populations. Often, they focus on proximal determinants of health with little engagement with important upstream factors and interactions.

Indeed, key opportunities for urban health are often taken up neither by urban health systems nor by other urban sectors (like housing, energy, or transportation). Urban health accordingly aims to enhance engagement, coordination, and integration among these actors to improve health outcomes.

Urban health versus Healthy Cities versus healthy cities

The term “healthy cities” may be used in at least three different ways, all of which relate to urban health, but with clear differences.

First, “Healthy Cities” refers to a movement and a programmatic approach, embodied in the various Healthy City networks and in local implementation at the city scale. Rooted in health promotion and the need for health solutions in cities from beyond the health sector, the Healthy Cities movement arose in Canada and Europe during the 1980s. The movement has continued to grow, with substantial regional and global policy influence (Barton and Grant, 2013; Grant et al., 2024; Tsouros, 2015).

The Healthy Cities approach generally involves city-led action on both specific thematic work and intersectoral governance (see, e.g., Green and Tsouros 2008; de Leeuw et al. 2014). It often involves municipal health authorities and actors with support from city leaders. In some contexts, these actions are set within a national framework, and they are often supported via local and regional Healthy Cities networks.

Healthy Cities is not synonymous with urban health. Rather, it is a modality for the practice of urban health which strives for a higher state of urban health—reflecting the two components of the definition presented here. Yet urban health encompasses a wider set of models for policy and practice than Healthy Cities. The former is urban-focused, encompassing the very broad set of actors and processes at all scales that influence urban phenomena, whereas the latter is city-focused, acting primarily through local governance at the city scale.

The second usage of “healthy city” refers to the functioning of the city itself—the ways in which it protects itself, evolves, adapts and grows sustainably. To thrive, cities must promote their own social and economic development; manage security (e.g., avoid political violence, terrorism); sustain good governance (e.g., avoid corruption); foster resilience; coordinate flows of goods, services and people to meet needs; and protect the sustainability of local ecosystems, among other tasks. These actions serve to create and protect assets and livelihoods, improve stability, and promote human and natural capital.

This usage is related to urban health because many of the actions taken to foster “healthy” urban functioning can also—if well-designed and managed—yield health benefits. The health of the city (in this sense) and of its population are closely connected, regardless of whether health is the primary aim of city leaders. Urban health seeks to illuminate the links between the health of the city and of its population, paving the way for integrated action, especially seeking to enhance the human health dividend from actions not originally directed at health.

A third common usage of “healthy city” refers more generically to a city with a high state of urban health, one that continually seeks to attain this state, and/or one whose processes are designed and managed in such a way as to foster urban health. Each of these is compatible with the proposed definition of urban health.

Urban health versus other contemporary rubrics

The modern rubrics of resilience, planetary health, One Health, and ecohealth each seek to understand, describe, and address complex societal challenges through broadly integrative approaches. Each is applicable to urban areas, though none is exclusively urban in focus.

Resilience is “the capability of a person, structure, or system to withstand shocks or stressors while maintaining or recovering function and continuing to adapt and improve” (Siri and Indvik, 2022). Like urban health itself, it is multifactorial, requiring integrated action and attention to complex interactions. The resilience community tends to focus more on infrastructure and institutions than on health, but resilience is an essential aspect of urban health, as recognized in the proposed definition and in the elements of strategic action (see Box 2).

Planetary health is “the health of human civilization and the state of the natural systems on which it depends” (Whitmee et al., 2015). It focuses on the relationships between the activities of human societies and earth systems and the ways in which impacts on those systems are threatening the basis for human thriving. The outsized influence of urban areas on earth systems makes them a central concern for planetary health. Likewise, the need to maintain health-supporting natural systems is integral to urban health, as recognized in the proposed definition. Nevertheless, planetary health tends to focus on higher-scale processes than urban health.

One Health is “an integrated, unifying approach that aims to sustainably balance and optimize the health of people, animals, and ecosystems” (One Health High-Level Expert Panel (OHHLEP) et al., 2022). It emphasizes the ways in which human and non-human life interact and how these interactions modify health outcomes for both. In practice, One Health often focuses on infectious disease transmission, though the framework is applicable to a broader set of issues. Because urban processes determine many human-animal interactions (e.g., through urban expansion, urban food markets, or the clearing of natural ecosystems for agriculture to feed urban populations), they are a critical consideration within One Health. Conversely, urban health necessarily engages with the dynamics of animal, plant, microbial, vector, and pathogen populations.

Ecohealth is “an approach that integrates natural and social sciences to understand and manage ecosystems and the interactions among human, animal, and environmental health” (Talukder et al., 2024). It is founded in the principles of “transdisciplinarity, systems thinking, multi-stakeholder participation, equity, environmental sustainability, and evidence for community-based interventions” (Charron, 2012). As for the other rubrics, the influence of urban areas makes them an important context in ecohealth. As such, ecohealth has strong connections to urban health, but where the former tends to focus on the interactions among ecosystems, human social systems, and health, urban health encompasses a wider range of physical and social determinants and has a more specific urban focus.

These are simple descriptions of complex rubrics, and various efforts have been made to more completely describe the differences and similarities among them (see, e.g., Lerner and Berg 2017; Talukder et al. 2024). Each describes a set of interconnected pathways and determinants of health that is applicable in urban areas. Urban health further defines linkages with and implications for the urban environment, processes, and populations.

Competing paradigms of urban health?

Cities have always acted to support the health of citizens—promoting safety, reducing environmental risks, limiting infectious disease spread, and implementing other health-promoting actions. Yet the modern conception of urban health is more recent, as reviewed elsewhere in this collection (Grant et al., 2024).

On the one hand, this development was influenced by secular trends that made cities more important, including: growing populations, urban assets, and risks in the context of ongoing urbanization and expanding cities; growing inequities and a greater visibility of slums; growing urban political influence; the evolution of new data sources; and a shift in development financing toward cities.

On the other hand, it was also influenced by conceptual shifts, including the inception of a rights-based legal framework for health; recognition of the cross-cutting basis of health determinants and the need for health beyond the health sector; an evolution from siloed to integrated thinking; a newfound emphasis on health equity; growing recognition of the role of complexity; and a shift in perception–from cities as problems to cities as solutions.

The breadth of different urban-focused disciplines whose work has helped usher in these conceptual shifts has led different actors to emphasize different aspects of and solutions for urban health challenges. Today, at least four strands of thought or paradigms are active in the urban health space (Kim et al., 2022):

Our proposed definition of urban health is intended to be compatible with each of these paradigms so as to foster strategic action while allowing diverse stakeholders to maintain their unique perspectives.

How a common definition can support strategic action

Consensus on definitions of urban and other terms and on the remit of urban health are vital preconditions for the successful development and coordination of effective strategic approaches to promote urban health. Common definitions can improve understanding and communication, simplify the process of setting shared goals, make assessment more feasible, and contribute to other objectives.

Yet the broad nature of overlapping interests in urban health is a challenge for such definitions because different stakeholders value and emphasize different aspects of urban health. The presentation of a standardized definition, while important for communication, should not be taken as a unilateral endorsement nor as a deprecation of other definitions or traditions, which can offer important insights arising from different ways of thinking about urban health challenges. Moreover, while a common definition is important for effective strategic action, the form of urban health policy, practice, and solutions will differ with local context.

We have proposed a definition for urban health intended to support strategic action. This is presented in Box 1 in the six official languages of the United Nations, in recognition of the universal nature of urban health challenges and the value of common understanding. We have also outlined the basic elements of strategic action, reviewed the subjects and scope of urban health practice, and explored the relationship of urban health to public health, Healthy Cities, and a set of contemporary rubrics addressing complex societal challenges. We hope this will bring useful clarity for urban health decision-makers, advocates and practitioners at all scales.