Essay Slum Health: From Understanding to Action Alon Unger*, Lee W. Riley “Slums are a manifestation of the two main challenges facing human settlements development at the beginning of the new millennium: rapid urbanization and the urbanization of poverty.” Anna Kajumulo Tibaijuka, Executive Director, United Nations Human Settlements Programme [1] doi:10.1371/journal.pmed.0040295.g001 “Jo lives—that is to say, Jo has not yet died—in a ruinous place, known to the like of him by the Figure 1. Kibera Shantytown in Nairobi, Kenya name of Tom-all-Alone. It is a black, dilapidated Home to nearly 1 million residents on the outskirts of Nairobi, Kibera is the world’s second largest street, avoided by all decent people…Now, these slum. Photo by Alon Unger. For a virtual tour, see: http://www.amref.org/index.asp?PageID=432 tumbling tenements contain, by night, a swarm of misery…As, on the ruined human wretch, vermin the least developed countries’ urban on these neglected communities and parasites appear, so, these ruined shelters have population live in slums [1]. Today’s already limited health care resources. bred a crowd of foul existence that crawls in and slums are unprecedented in their sheer In this essay, we show that the defining out of gaps in walls and boards; and coils itself magnitude, their rapidity of growth, physical and legal characteristics of to sleep, in maggot numbers, where the rain drips and their worldwide distribution in; and comes and goes, fetching and carrying [1,5]. They represent a fundamental Funding: The authors received no specific funding fever…” transformation of the physical and for this article. social environment of urban life and Charles Dickens, Bleak House [2] Competing Interests: The authors have declared human health. that no competing interests exist. his year, 2007, marks the first Like Dickens’ Tom-All-Alone, slums Citation: Unger A, Riley LW, et al. (2007) Slum health: time in human history that are synonymous with squalid living From understanding to action. PLoS Med 4(10): e295. Tthe majority of the world’s conditions. A visit to the favelas of doi:10.1371/journal.pmed.0040295 population will live in cities [3]. The Rio de Janeiro, the shantytowns of Copyright: © 2007 Unger and Riley. This is an United Nations (UN) projects the Nairobi, or the jhopadpatti of Mumbai open-access article distributed under the terms world’s urban population to grow by shows that a slum, by any name, is of the Creative Commons Attribution License, an unhealthy place to live (Table 1, which permits unrestricted use, distribution, 2 billion before 2030. More than 90% and reproduction in any medium, provided the of this growth will take place in the Figures 1 and 2; for a virtual tour of original author and source are credited. least developed countries [4], and one such slum, see: http://www.amref. Abbreviations: DALY, disability-adjusted life year; will be concentrated in the bleakest org/index.asp?PageID=432). Many TB, tuberculosis; UN, United Nations parts of the city—human settlements health outcomes are worse in slums known as slums. Already nearly a third than in neighboring urban areas or Alon Unger is with the Departments of Medicine and Pediatrics, University of California, Los Angeles, Los (32%) of the world’s population and even rural areas [6–8]. Moreover, the Angeles, California, United States of America. Lee W. more than three-fourths (78%) of formal health sector encounters slum Riley is with the Division of Infectious Disease and residents only when they develop late- Epidemiology, School of Public Health, University of California, Berkeley, California, United States of stage complications of preventable America. The Essay section contains opinion pieces on topics chronic diseases, as we have described of broad interest to a general medical audience. * To whom correspondence should be addressed. elsewhere [9]. This takes a costly toll E-mail: [email protected] PLoS Medicine | www.plosmedicine.org 1561 October 2007 | Volume 4 | Issue 10 | e295 California. The built environment Table 1. Slums Go By Many Names is also directly related to accidental Language or Region Term injuries, such as falls and burns [19]. French bidonville, taudis, habitat précaire, habitat spontané, quartier irrégulier Physical characteristics of slums not Spanish asentamiento irregular, barrio marginal, barraca, conventillos, colonia only magnify the consequences of popular, villa miseria, ciudad perdida natural or man-made disasters, but also German elendsviertel hinder rescue efforts [20]. Arabic mudun safi, lahbach, brarek, medina achouaia, foundouks, tanake, aashwa’i Overcrowding. Slum dwellings have Russia/Eastern Europe trushchobi, kartonsko naselje high occupancy rates in all-purpose Portuguese favela, quartos do slum, morro, loteamento, cortiço, comunidade Turkish gecekondu rooms. Cooking, sleeping, and living 2 English hood, ghetto, squatter camp, shantytown with 13.4 people per 45 m room, as South Asia chawl, ahata, katra, bustee, katchi abadis, watta, pelli gewal, jhopadpatti in the slums of Kolkata, India [21], Africa umjondolo, mabanda, kijiji places residents at risk of respiratory infections, meningitis, and asthma From [1]. doi:10.1371/journal.pmed.0040295.t001 [22,23]. In Manila, the Philippines, children living in squatter settlements slums profoundly affect the health of forces residents to occupy unused are nine times more likely than other these communities and may also serve or undesirable land. For example, children to have tuberculosis (TB) as potential targets for immediate between 1991 and 1997, 1.5 million [24]. Epidemic-prone infections like intervention. and 1 million people were evicted from pertussis cluster in areas of urban central areas of Shanghai and Beijing, poverty [25], and overcrowding Defining Slums and the Challenge respectively [13]. Such dislocations may even fuel potentially emerging of Slum Health out of the city center force large epidemic diseases like SARS or In 2002, the UN operationally numbers to commute longer distance influenza [26]. Crowding is also defined slums as those communities to their original place of work, where associated with rheumatic heart disease, characterized by: insecure residential they brave the road, by foot or in a chronic and debilitating disease status, poor structural quality of overcrowded and dangerous vehicles, facilitated by increased transmission of housing, overcrowding, and inadequate putting themselves at risk for road- group A Streptococcus pyogenes infections access to safe water, sanitation, and traffic injuries [14]. Slum locations and lack of early treatment [27]. other infrastructure [10] (Table 2). may be unused or undesirable because Inadequate access to safe water. The 2003 UN report, The Challenge of their hazardous geography, such Poor water quality is a leading cause of Slums, is the most comprehensive as landslide- or flood-prone areas, of morbidity and mortality worldwide account of the demographic and or unsafe or polluted environments. and a defining danger of living in socioeconomic indicators of slums Moreover, their residential status slums [28]. Many life-threatening worldwide [1]. It details not only the limits their ability to fight for the right infectious diseases are associated high concentration of poverty and to a safe environment. In 1984, the with contaminated water in slums, substandard living conditions in slums, accidental release of methyl isocyanate such as cholera and hepatitis (Table but also the insecurity of tenure and from a pesticide factory in Bhopal, 2) [29]. Lack of access to water also marginalization from the formal sector, India killed more than 20,000 slum restricts water intake, sources for infant including basic health services. residents; the factory was built after formula or cooking, bathing and the settlement had already been in personal hygiene. Infrequent bathing Conditions of Slum Life and existence [15]. Even in the United is associated with scabies and bacterial Health—Using the UN Operational States, Hurricane Katrina unmasked skin infections, a subset of which (i.e., Definition the vulnerability of residents of poor group A streptococcus) can lead to Slums are areas of “concentrated neighborhoods in flood-prone areas acute glomerulonephritis [30]. disadvantage” [11]. The physical and and also the neglect of this population Inadequate access to sanitation legal characteristics enumerated by by political institutions [16,17]. and other infrastructure. The lack the UN are intimately related with Poor structural quality of housing. of infrastructure affects all aspects population composition and dynamics, Slum housing is densely packed and of life, including waste collection social environment, poverty, and poorly built with substandard or and sewers, public transportation, marginalization. Health comparisons of even flammable materials. Houses policing, education, and electricity rural versus urban areas, or emphasis built against hillsides are subject to supply. Five million slum residents on the urban health “penalty” or landslides during heavy rain, and live without toilets in Mumbai; if each “advantage,” do not highlight the inferior building standards cause many person defecates half a kilogram specific health determinants of slums thousands of deaths from earthquakes, per day, 2.5 million kilograms of [12]. Here, we use the UN operational especially where urbanization and human waste contaminate their criteria to show that the conditions poverty collide [18]. In Bam, Iran, poor