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date: 24 July 2021

Street Science: Community Knowledge for Global Health Equityfree

Street Science: Community Knowledge for Global Health Equityfree

  • Jason CorburnJason CorburnDepartment of Public Health, University of California Berkeley


Street science is the processes used by community residents to understand, document, and take action to address the environmental health issues they are experiencing. Street science is an increasingly essential process in global urban health, as more and more people live in complex environments where physical and social inequalities create cumulative disease burdens. Street science builds on a long tradition of critical public health that values local knowledge, participatory action research, and community-driven science, sometimes referred to as “citizen science.” Street scientists often partner with professional scientists, but science from the street does not necessarily fit into professional models, variables or other standards of positivist data. Street science is not one method, but rather an approach where residents are equally expert as professional scientists, and together they co-produce evidence for action. In this way, street science challenges conventional notions in global health and urban planning, which tend to divorce technical issues from their social setting and discourage a plurality of participants from engaging in everything from problem setting to decision-making. Street science does not romanticize local or community knowledge as always more accurate or superior to other ways of knowing and doing, but it also recognizes that local knowledge acts as an oppositional discourse that gives voice to the often silent suffering of disadvantaged people. At its best, street science can offer a framework for a new urban health science that incorporates community knowledge and expertise to ensure our cities and communities promote what is already working, confront the inequities experienced by the poor and vulnerable, and use this evidence to transform the physical and social conditions where people live, learn, work, and play.


  • Environmental Health
  • Global Health
  • Public Health Policy and Governance
  • Theory and Methods


In communities around the world, concerned lay publics are demanding a greater role in the scientific research and decision-making processes impacting their lives. From activists questioning the impacts of climate change to those concerned with environmental exposure and disparate disease burdens that disproportionately impact the poor and vulnerable groups, lay people are increasingly wrangling with scientists about issues of truth and method, exerting policy pressure on them from the outside, and also locating themselves on the “inside” of research. These activists are challenging not just the political use and control of science and expertise, but also the content and processes by which technical knowledge is produced, by claiming to speak credibly as experts in their own right. Communities suffering the greatest environmental hazards and health disparities are asserting that their lived experience, intimate knowledge of place, chronic and communicable disease coping strategies, and cultural traditions all help qualify them as people who know about things scientific and who can partake in the often exclusive but powerful discourse of public health decision-making. Importantly, these same “street scientists” in low- and middle-income countries (LMICs) argue that urban planning and development tools and techniques were developed “in the North” and reflect taken-for-granted assumptions that may not apply in their contexts (Watson, 2014). Further, increasingly accessible measurement tools and technologies are putting analyses and knowledge, once the exclusive domain of professionals and highly specialized experts, into the hands of everyday “citizen scientists.” The result is that global urban public health decision makers are being forced to take account of community knowledge and to find new ways of fusing the expertise of professional practitioners and scientists with the contextual intelligence—or local knowledge—that community residents possess (Corburn, 2005).

This article highlights the cognitive and normative contributions and limitations of street science. Although neither romanticizing nor essentializing community knowledge, it is suggested here that the knowledge used to legitimate science policy ought to be co‑produced, or simultaneously dependent on both natural and social order, professionals and lay people, state institutions, and nongovernmental organizations (NGOs). This article elaborates on the slippery concept of street science and how it might be used to inform research and practice for more healthy cities by highlighting how residents in two Nairobi informal settlements, Mathare and Mukuru, engaged in research and decision-making to address the health hazards they faced. This article reveals how professionals and residents co-produced the collective knowledge base used to legitimate decisions, evaluate outcomes, and improve population health.

Street Science: The Co-Production of Science Policy Expertise

Street science can be viewed as the application of the co-production of expertise with an explicit social justice framework. One idea behind the co-production of knowledge is that institutionalized notions of expertise must be questioned from the outset of inquiry, and hard demarcations between nature and society challenged in order to explore how the social is often embedded in the scientific (Jasanoff, 2004). Urban health challenges, such as climate change and persistent health inequities experienced by certain populations and communities demand that scientific processes be more relevant to solving, not just analyzing, global health challenges.

The co-production suggested by street science also borrows from the work of Elinor Ostrom, who defined co-production as “a process through which inputs from individuals who are not ‘in’ the same organization are transformed into goods and services” (Ostrom, 1996, p. 1073). Ostom’s work focused on urban sanitation provision and suggested that state and community residents each offered complementary contributions to the delivery of public goods: the state has resources and technical expertise that can best deliver “trunk” infrastructure, and communities have local information, time, and skills that allow them to best deliver “feeder” services. Ostrom emphasized the co-dependence and complementary forms of knowledge that together can improve outcomes (Ostrom, 1996).

Mitlin (2008), among others, has aimed to expand on Ostrom’s work with an explicit focus on the context of the urban poor in the Global South. For Mitlin (2008), co‑production is also about how civil society actors can simultaneously work with the state for services and goods, but also challenge and aim to change the ways the state makes decisions and allocates resources. Mitlin calls this “bottom-up co-production” and suggests that co-production is a strategy used by civil society to “enable individual members and their associations to secure effective relations with state institutions that address both immediate basic needs and enable them to negotiate for greater benefits” (Mitlin, 2008, p. 339). This article offers a specific example of street science from urban Kenya and reveals how both dimensions of co-production—opening up expertise in knowledge production and in service delivery—are revealed in practice.

Street science as used here should not be viewed as a full-fledged theory—claiming law-like consistency and predictive power—but rather as an idiom, or a way of interpreting and accounting for complex phenomena so as to avoid the strategic deletions and omissions of most other approaches to understanding the role of the public in science policy (Jasanoff, 2004, p. 3). Thus, a central aim of the street science framework is to help clarify how power originates, where it gets lodged, who wields it, by what means, and with what effect within the complex network of science policy making (Wynne, 2003).

Antecedents to Street Science

Street science builds on a long tradition in public health and other fields of community based and led participatory action research, often called community-based participatory research (CBPR) (Israel, Eng, Schulz, & Parker, 2005). CBPR aims to combine professional techniques with community insights to define problems and research questions, gather and analyze data, and direct action and evaluate interventions. This method, building from participatory action research (PAR), aims to make research more democratic, ensure the poor and people of color are not excluded from decisions that impact their lives, and incorporate local knowledge and lived experience into research and action (Chambers, 1997). In these ways, CBPR can enable street science processes to open up how authoritative technical knowledge is produced in society and gets stabilized and institutionalized over time so that it becomes a “given” or “taken-for-granted truth.” Like CBPR, street science aims to problematize the origins and substance of the meanings of policy issues and who was included or left out of generating these meanings, and builds on constructivist work in the social sciences, highlighting that scientific legitimacy is simultaneously a social, political, and material phenomenon, none of which can be disentangled from another (Agarwal, 1995). Street science aims to respond to those critics of CBPR by suggesting that science and technology are not “contaminated” by society, but rather embed and are embedded in “social practices, identities, norms, conventions, discourses, instruments, and institutions—in short, in all the building blocks of what we term the social” (Jasanoff, 2004, p. 3).

Table 1 highlights the dimensions of regulatory science (Jasanoff, 1990), research science and street science (Corburn, 2005). We might understand regulatory science as the body of scientific and technical knowledge that aims to provide answers to public regulatory decision-making, whereas research science is legitimated within a defined scientific field through peer review and related internal norms. (Bourdieu, 1975; Kuhn, 1977).

Table 1. Street Science Compared to Regulatory and Research Science

Regulatory science

Research science

Street science

Truth claims

Aim to inform public policy

Disciplinary significance

Lived experiences of community members and contributions to action


Government and industry

Universities, government, and industry

Community members and groups


Published reports and data

Peer-reviewed publications

Reports, peer-reviewed publications, and popular communications


Compliance with existing law and economic interests

Professional recognition and legitimacy in selected field

Social justice and human rights; education and community empowerment

Approach to uncertainty

Reject & seek additional data

Reject & seek additional data

Accept, act with precaution and to prevent further harm


Legislatures and courts (meet legal procedures); audits; cost-benefit analyses

Peer review

Community residents, social movements, courts, and media

Source: Adopted, in part, from Liévanos, London, and Sze (2011).

Street Science in Global Urban Health

By the year 2020, over half the world’s population was living in cities, and this is only expected to increase. Global health is urban health. Yet, at least 25% of the planet’s urban residents are living in informal settlements, or slums. According to the UN, slums are human settlements that have the following characteristics: (a) inadequate access to safe water, (b) inadequate access to sanitation and other infrastructure, (c) poor structural quality of housing, (d) overcrowding, and (e) insecure residential status. Yet, as this article emphasizes, there is no single definition that adequately captures the characteristics of “informal settlements” that contribute to poor health or well-being. For instance, the UN defines informal settlements as unplanned squatter areas that lack street grids and basic infrastructure, with makeshift shacks erected on unsanctioned subdivisions of land. Street scientists reveal that health in informal settlements demands exploring not just how physical deprivations in slums might influence disease and death, but also how economic poverty, social inequalities, and political disenfranchisement act to stymie well-being or support resilience (Corburn & Riley, 2016).

Cites and what influences health, disease, and death in cities are complex and multifactorial. Street science can help reveal this complexity from both the perspectives of those living in cities and professionals with diagnostic and analytic tools. As this article suggests, street science helps conceptualize urban places as doubly constructed; through material and physical building (the buildings, streets, parks, etc., of the “built environment”) and through the assigning of meanings, interpretations, narratives, perceptions, feelings, and imaginations to these places that only come from local people and culture. In this way, street science opens up an urban global public health to the relational, or multidimensional view of urban places and health (Cummins, Curtis, Diez-Roux, & Macintyre, 2007). Street science can help reveal the meanings and context-specific differences in social processes, such as power, cultural expression, and collective action, that are often revealed through the construction and reconstruction of environmental assets and hazards, material forms, and social meanings in cities and urban areas.

Importantly, street science emphasizes that there is an alternative to the single, independent variable-centered view of places used in most neighborhood effects on health, built environment and health, and urban design and health research. This research tends to turn characteristics of places, whether physical or social, into covariates in regression models, obscuring the subjective meanings people assign to make sense of their physical and social environments. Further, social marginalization is not reducible to single variables, as education, employment, environmental quality, racism, and the affordability and accessibility of other life-supporting resources, such as housing, food, and social supports, are all multifaceted and interconnected.

Figure 1 conceptualizes the dimensions of the street science approach to urban places, which seeks to emphasize not just the nodes (i.e., the “Ps”) but rather how all nodes interact with one another in dynamic, complex ways. Street science offers a way to understand and engage with the people living in a community and understanding and valuing their culture, norms, values, knowledge, and histories. Capturing this information in respectful ways will require participatory and democratic methods of inquiry. Community knowledge captured through street science recognizes that local health and place issues are interpreted, narrated, perceived, felt, understood, and imagined by people and institutions, and capturing how these narratives are constructed and contested is essential. Street science is a political processes, so we must be aware of how it can embed, reflect and confront power relations (Figure 1).

Figure 1. Street science: Nodes and relations of inquiry and action.

Source: Corburn and Karanja (2014).

Street Science, Toxic Stress, and Healthy Communities

A key challenge in global and urban health research and action is identifying the mechanism(s) through which characteristics of urban places get “into the body” or are embodied to influence well-being. For example, in environmental health the inhalation pathway is a key site for studying the dose–response of, for instance, how much particulate pollution contributes to respiratory disease. Yet, what if the exposure is place based, such as green space, a neighborhood park, or unsafe streets? Further complicating the dose–response function of urban place characteristics and health is that many communities have multiple, overlapping hazards (and assets) that create cumulative disadvantage or advantage for some over many years or even a lifetime.

Street science offers insights for approaching biologic embodiment. For example, as Krieger (2005) has so eloquently stated:

Embodiment reminds us that a person is not one day African American, another day born low birth weight, another day raised in a home bearing remnants of lead paint, another day subjected to racial discrimination at work (and in a job that does not provide health insurance), and still another day living in a racially segregated neighborhood without a supermarket but with many fast food restaurants. The body does not neatly partition these experiences—all of which may serve to increase risk of uncontrolled hypertension, and some of which may likewise lead to comorbidity, for example, diabetes, thereby further worsening health status.

(Krieger, 2005, p. 353)

Street science offers one way to help capture these multiple exposures in places that are so critical for understanding health inequities. Figure 2 highlights a set of multiple and cumulative insults or “stressors” in the urban environment that together are known to influence specific health outcomes and contribute to premature mortality (McEwen & Gianaros, 2010). Street science aims to identify toxic stress through engagement with those that are experiencing these environmental stressors. . For healthy cities and communities around the world, the concept of toxic stress is critical for helping to highlight the mechanism or the multiple factors that are contributing to illness and premature mortality. The idea behind toxic stress is that although single adverse events can be lifesaving—think of the body’s fight-or-flight mechanism—constant and prolonged adversity becomes toxic because our bodies overreact and this wears away at our immune and other biologic systems. The prolonged activation of the body’s stress response systems disrupts the immune system and the development of the brain, both of which contribute to greater susceptibility to infections, chronic diseases, and poor mental health (Shonkoff, Garner, Committee on Psychosocial Aspects of Child and Family Health, & Committee on Early Childhood, Adoption, and Dependent Care: Section on Developmental and Behavioral Pediatrics, 2012).

Figure 2. Multiple adverse events that contribute to toxic stress and poor health.

Source: Author.

Street Science for Healthier and Equitable Cities: The Mathare Informal Settlement, Nairobi, Kenya

The Mathare Valley is an informal settlement approximately 6 kilometers to the northeast of Nairobi’s central business district and is bordered by Thika Road to the north and Juja Road to the south. The informal settlement has approximately 300,000 people, almost all of whom are renting shacks from structure owners. There are 13 distinct villages in Mathare: Mashimoni, Mabatini, Village No. 10, Village 2, Kosovo, 3A, 3B, 3C, 4A, 4B, Gitathuru, Kiamutisya, and Kwa Kariuki. The settlement sits within a valley of the Mathare and Gitathuru rivers.

In Nairobi, Kenya, close to 65%% of the population lives in informal settlements, or slums, on about 10% of the city’s land area. (APHRC, 2014). Children under age 5 living in Nairobi’s slums are almost three times as likely to die than their counterparts in the rest of the city, and women experience disproportionate health burdens compared to men (Kimani-Murage et al., 2014). For example, over a quarter of all women and girls in Nairobi’s slums reported an episode of diarrhea in the past month, compared to about one-fifth of all Kenyans. Over 36% of slum-dweller women report being physically forced to have sex, and over one-third report being sexually abused (Swart, 2012). In part a reaction to this “structural violence,” residents of the Mathare and Mukuru informal settlement in Nairobi, Kenya, organized and partnered with the Federation of Kenyan Slum Dwellers called Muungano wa Wanavijiji (Muungano). Muungano is part of the global nongovernmental organization Slum Dwellers International (SDI), which works in over 30 countries with the urban poor to secure human rights, prevent evictions. and promote pathways out of poverty. From 2010–2016, SDI and Muungano developed a street science partnership with the University of California, Berkeley (UCB) and the University of Nairobi to document living conditions in Mathare and Mukuru and advocate for health-promoting changes (Muungano Alliance, 2017). The following are some specific street science activities conducted by Nairobi slum dwellers in partnership with SDI, UCB, and University of Nairobi (Lines & Makau, 2018).

The aims of the street science, in this case “slum science,” collaboration were to help mobilize residents, gather data that reflected community concerns, and use that information to inform interventions that improved lives and living conditions. From 2010–2019, street science data gathering, mapping, analyses, and interventions occurred, including household enumerations, water and sanitation facility mapping, drinking water system design and operation, and air pollution monitoring. The different processes and issues mobilized women, youth, and others not frequently included or valued in the data-gathering and sense-making process (Makau, Dobson, & Samia, 2012).

In 2009, the United Nations Environment Programme (UNEP) and the Kenyan National Environment Management Authority (NEMA) proposed to clean up the Nairobi River and its tributaries, citing health and environmental risks. A concern of Muungano and its network of slum dwellers was that tens of thousands of urban poor residents living alongside waterways in Nairobi would be evicted through this river clean-up program (Weru, 2016). In Mukuru, illegal dumping, flooding, and industrial pollution threatened residents’ health, and the Nairobi City County declared the settlement a Special Planning Area (SPA) in August 2017 (Dodman, 2017). In each community, Muungano and the universities designed and implemented a detailed household survey, training and employing residents in data gathering. Over 12,000 households were surveyed and the entire community mapped by teams consisting of residents, Muungano, and SDI partners. Satellite images were downloaded of the entire community. Large maps were printed and shared during focus group meetings led by Muungano members. Discussions at these meetings included community health priorities, and the conversations informed more detailed community science efforts. Teams of residents, university students, and NGO partners walked every meter of the community to document the locations of each water point, toilet, electricity power pole, food vendor, dump site, school, community facility and other assets and hazards. The universities supported turn these field-based maps into an electronic dataset and worked with SDI to create detailed geographic information system (GIS) maps of the physical and social assets and hazards identified by residents.

Making the Invisible Visible

This type of Street Science in Mathare helped make the everyday hazards residents faced more visible to themselves and outsiders. For example, map making by residents highlight the number of people and types of community activities that would be displaced by the UNEP river program (Figure 3). These data were presented to the UN and local government by residents in an effort to stop evictions. The data visualization combined with community mobilization resulted in a temporary stay of planned evictions in Mathare. One result was a recognition by the state, for the first time, that community residents working in partnership with universities, could produce policy-relevant data.

Figure 3. Community identified structures impacted by UNEP River Clean-up Program.

Source: SDI-Muungano, Mathare Zonal Plan (reproduced with permission).

Sanitation and Women’s Health

A second key result of the processes in Mathare was a finding that girls and women were disproportionately burdened from inadequate sanitation (Figure 4). Another map-making process revealed the uneven access to toilets across Mathare. However, it was survey and focus group data that complemented the spatial mapping to highlight the serious health consequences of the maps. For example, household survey data revealed that over 83% of Mathare residents relied on an unimproved pit latrine and that over 60% used a “flying toilet,” which is the term used for defecating into a plastic bag and throwing it into an open dump.

Figure 4. Locations of toilets in Mathare informal settlement, Nairobi.

Source: Corburn and Karanja (2014).

We also heard in focus groups with Mathare women about the indignity they endured from a lack of private, safe, well-lit, nearby toilets. One women noted:

Past eight, we can’t go out to use the toilet. There is no lighting and the men drinking Chang’aa [local alcohol] on that side, get violent with us, even girls. We are forced to use a bucket . . . a bucket in one room in front of your children, fathers and brothers. Can you imagine? Sometimes we use the flying toilets: at night but your neighbors don’t like this. Without any garbage collection, I wake up at dawn and sneak away to empty the bucket or dispose the bag. There is no dignity in our toilet situation.

(Corburn & Karanja, 2014, p. 266)

We heard in focus groups with girls that they were more likely than boys to miss school because of sanitation-related illness and lack of safe, private, and hygienic toilets at their school. A lack of adequate toilets in schools decreases the attendance of girls, especially during their menstrual cycle. One schoolgirl noted:

As girls, when we don’t have a toilet in school, we are forced to stay with one pad for a whole day. I know many girls who just do not come to school during those days. Even if we have a toilet at school and we have to share them with boys, girls will avoid them and stay home. We do not have a bath place so I know when you have your period you do not want to smell in school, so us girls avoid it.

(Corburn & Karanja, 2014, p. 265)

For girls and women in Mathare, toilets are a relational issue of inadequate infrastructure, safety, economic opportunity, stigma, dignity, and human health.

Street Science to Health Policy

The data-gathering processes in Mathare were shared and discussed with community planning teams. Meetings between residents and service providers were also held, and residents used maps of the distribution of water points to advocate with the Nairobi Water and Sewer Company to install new piped water service in Mathare. Muungano used the data to advocate not only for piped water but also for a community-run management scheme so that economic opportunities and oversight responsibilities would go to local residents. By 2014, over 21,000 Mathare households were being served by piped, in‑home water, and Muungano was helping to manage the system as well as new, public water taps serviced by the Nairobi Water and Sewer Company (Urban Poor Fund International [UPFI], 2014). The campaign also went beyond a boutique project. The street science process and community-driven management system formed the basis of a new model and policy for improving water supply access for slums across Kenya, called the Mathare-Kosovo Water Model (Kenyan WSTF, 2010).

In Mukuru, street scientist youth were trained to monitor local air pollution. Nairobi County has only a few air pollution monitors, and at the time there were no data of air pollution exposure inside the city’s slums. Yet, respiratory illnesses and upper-respiratory infections were one of the most frequently cited illnesses by slum dwellers (Dianati, Zimmerman, & Milner, 2019; Egondi, Muindi, Kyobutungi, Gatari, & Rocklöv, 2016). Youth also made films about air pollution to communicate to others in the community. The “slum scientists” working with the universities, SDI, Muungano, and the Stockholm Environment Institute (SEI) Africa wore backpacks with a Dylos air pollution monitor during daily and evening activities. The monitor captured constant particulate matter (Pm2.5), ammonia (NH3), and nitrogen dioxide (NO2) readings. These data were combined with daily diaries from residents about what they were observing in their community, such as a large plume of smoke from neighboring industries, waste burning, and open cooking. Some of the citizen scientists were community health workers (CHWs), and they are sharing the findings across Mukuru to educate residents on how to recognize and avoid hazardous air pollution.

Perhaps most importantly, the monitoring data and diaries are being used to document the high levels of pollution in the community, and helped influence policy actions. For example, the slum scientists found high levels of nitrogen dioxide and Ammonia in Mukuru, and interventions focused on disposing waste from dump sites and pressuring the World Bank to expand a sewer to capture human waste, both key sources of ammonia. The findings have been integrated into the Special Planning Area (SPA) recommendations for Mukuru. The findings were also instrumental in shaping the Nairobi Air Quality Action Plan, the first-ever policy for the city, completed in 2018 (Nairobi City County, 2018).

The Challenges for Street Science in Global Health

The case presented here reveals the potential and challenges for street science in global urban health. First, organizing youth and residents around scientific and health issues can be challenging, especially when engaged research projects demand long-term, multi-year commitments, young people may have limited available time, and some residents view their stay in the informal settlements as temporary or transitional. However, one recommendation from our experience is that the street science processes should engage young people early and often, especially as new technologies, web, and social media geared toward youth become commonplace as mapping and data gathering tools. Partnering with youth can also help ensure that street science is fun and tied to local culture and even to a broader fundraising strategy. Engaging youth can also support street science as a strategy to build new organizational capacity, leadership, and power, especially when community members drive the research questions; selection of appropriate data; and interpretation, presentation, and use of results.

A second challenge is that the rapid pace of technological change and sophistication may lead some groups to choose to leap-frog and start with the latest, most advanced tools. Our experience suggests that this rarely builds on local knowledge and may create an over-dependency of community groups on technology and outside expert advisors. Hence, it is suggested here that street science processes are most successful when they build incrementally from small to larger scale, from less to more complex, and from low to higher technology. This trajectory can be rather quick with skilled partnerships and collaborations.

A third challenge for street science is to focus on both bonding and bridging social capital, where bonding helps civil society groups and residents build trust and partnerships among themselves, and bridging allows community members to engage with academic scientists and other outsiders. Often, the goal of street science is to build community alliances, gather local knowledge, and challenge an inaccurate characterization of a place done by outsiders. The case presented here suggests that street science can help mobilize knowledge and power inside and outside local communities.

A fourth challenge for Street Science is identifying credible intermediaries—an institution or agent who can champion and translate local information into professional terms. Intermediaries, also called boundary spanners, can be professionals themselves or effective local people affiliated with a respected institution. The academic partners working with SDI in Nairobi helped play this role. Scientists and policy administrators often need “translators” when working in communities, particularly culturally distinct communities, because the value of local knowledge to professional work may not be obvious at first glance. Importantly, intermediaries do not speak for local people, but instead work to increase the “standing” of what they know in professional settings.

Fifth, linking concrete community health concerns with broader policy frames and campaigns is another challenge of street science. Characterizing one’s community by selecting certain features to investigate always requires value judgments about what to leave out. Instead of viewing this as a weakness or limitation, this article suggests that a community-led action research process be explicit about the community’s issues and policy objectives from the outset, with place-based health inequities being one logical policy frame.

Street Science for Global Health Equity

As global public health practitioners and social epidemiologists recognize that “place matters” for understanding why some populations in some places get sick more often and die prematurely, street science will be increasingly important for gathering information on the features and characteristics of places that influence well-being and moving from research to policy. Capturing both hazards and assets is crucial, and a street science approach is vital for ensuring both residents and researchers engage in a collaborative process for deciding what information to capture, what role different technologies can play, and how to share evidence within and outside the community. What is crucial is that community members consider street science as one part of an ongoing global health equity advocacy and policy change strategy.

The case also highlighted that policy-relevant information is held by community members, and if ignored a potentially lethal hazard might be missed. Too often in environmental health science, a lack of data leads to the assumption of a lack of harm. Community knowledge does not replace professional science nor devalue scientific knowledge itself, but rather can revalue forms of knowledge that professional science has excluded (Corburn, 2005).

Street science demands that global health equity embrace intersectionality and anti-essentialism—or the notions that no person or community has a single, easily stated, unitary identity and that no absolute “truth” exists from any one perspective. Global urban health demands embracing the multiple exposures, behaviors, and disease burdens in communities, and holds that professional tools and models are often inadequate to capture these data. In this way, street science aims to rectify the tendency toward reductionism in global health science and extend the knowledge base used for decision-making. Street scientists can highlight an epistemological flaw when professional models “wash out” particularities within the community, such as the heterogeneity of exposures and the social and material aspects of exposure and vulnerability (Agarwal, 1995). Street science can improve scientific assessments by revaluing information that may be “controlled for” or ruled out by professionals as “a way of living” or matters of individual choice.

Street science can also enhance procedural democracy in global health science, which occurs when previously marginalized and silenced voices are included in research and decision-making, especially in a world where expertise tends to exclude people. By explicitly recognizing community expertise, street science can provide the opportunity for communities to speak back to the often hegemonic power of scientific expertise, and ensure that problems are defined, analyzed, and addressed in ways that reflect actual lived experiences. Issues of research transparency, trust, ownership, and self-determination continue to concern community groups, especially the poor and people of color who have either been ignored by researchers or, when asked to participate as subjects, are often abandoned in the end by researchers intent on analyzing results only for their own advancement and not for community improvement. In street science, community members are more likely to “see themselves” in science, thus finding it more acceptable, potentially saving time and money in policymaking. Local knowledge can also raise previously ignored distributive justice questions, forcing science to examine who is at risk, not just whether a particular level of risk is acceptable.

Toward a New, Urban Health Science

Street science does not happen easily, as some communities and professionals alike remain skeptical of local knowledge and will almost always find it easier to defer to the politically powerful knowledge of private interest groups or other professional scientists. Yet, as this article has argued, street science has the potential to fundamentally open up previously taken-for-granted aspects of scientific autonomy and objectivity used to underwrite legitimate political decisions. Unorganized communities may be at a disadvantage, as will be well-organized communities whose participation may occur too late in decision-making process to offer alternatives to dominant or default options. In addition, some participatory processes may be too ad hoc or issue specific to have a sustained influence over global health decision-making. Yet, street science holds the potential to craft a new model of urban health science that is necessary to confront the complex social, environmental, and technical inequalities that are perpetuating health inequities and improve health equity for those experiencing the greatest suffering.