Climate change and public health: a challenge to urban centres Carlos Corvalan and Diarmid Campbell-Lendrum World Health Organization, Geneva, Switzerland. XI WORLD CONGRESS ON PUBLIC HEALTH VIII BRAZILIAN CONGRESS ON COLLECTIVE HEALTH Riocentro Convention Center Rio de Janeiro, 21 - 25 August, 2006

URBANIZATION: Proportion of global population living in cities has increased dramatically in past Century. 1900: 15%. Now : 50% Population growth and urbanization, 1900-2005 6 5 Rural 4 3 2 Urban 1 1900 2005

Challenges from climate change for developing country cities Geographical location: e.g. many are located on coasts, vulnerable to both sea level rise and storms; Built environment: e.g. many cities experience a significant urban heat island effect, exacerbating the impacts of heatwaves; Co-exposures: e.g. many cities have high levels of air pollution, which interact with high temperatures to increase mortality and morbidity Weak infrastructure: e.g. high population density and poor sanitation waste/disposal promotes transmission of important infections.

Does climate change have a large impact on health? Burden of disease by region: Climate change and urban air pollution Disability Adjusted Life Year per million. World Health report 2002. Climate change Air pollution Africa region South-East Asia region Eastern Mediterranean region Latin America and Caribbean region Western Pacific region Developed countries Cardio- pulmonary diseases Respiratory infections Trachea/ bronchus/ lung cancers Diarrhoeal diseases Malaria Unintentional injuries Protein-energy malnutrition

Health vulnerabilities Heatwaves: Urban heat island effect Interaction with air pollution Weak social networks Lack of early warning systems and public health information Urbanization brings range of health vulnerabilities to CV &CC: Most obvious = heatwaves. Most cities show a large heat island effect, registering 5-11°C warmer than surrounding rural areas (7). But the effects of land cover change on climate are not limited to small areas: in southeast China, land use change from urban sprawl has been estimated to account for ~0.05°C warming per decade since 1978 (8).

Heat Island effect http://adaptation.nrcan.gc.ca/perspective/health-03_e.asp

12-day Heatwave, 3-14 Aug, 2003 Maximum Temperature, Aug 10 Excess Mortality: France: > 14,000 Italy: ~ 10,000 Spain & Portugal: ~ 5,000 Etc. Total = ~35,000

Health impacts: Heatwaves Heatwave in France, 2003. Over 14,000 people died

Health vulnerabilities 2. Floods and storms: Largest cities are on the coast Degradation of natural protection Poor quality housing in exposed areas Inadequate disaster response plans Caracas 1999. Construction patterns in many developing cities have resulted in a combination of degradation of natural protection (deforestation, building on floodplains etc.), poor quality housing construction on exposed slopes, and extensive ground coverage of concrete without adequate drainage.

Health Impacts of Floods Immediate deaths and injuries Non specific increases in mortality Infectious diseases – leptospirosis, hepatitis, diarrhoeal, respiratory, & vector-borne diseases Exposure to toxic substances Mental health effects Increased demands on health systems Philip Wijmans, LWF/ACT Mozambique, March 2000

Hurricane Katrina

Health vulnerabilities 3. Infectious disease: Inadequate water and sanitation provision High population density and high contact rates High levels of imported infections Inadequate disease warning, control and treatment

Urban infectious disease: Dengue Modelling studies suggest that climate change would increase the proportion of the global population exposed to dengue from about 35%, to 50-60%, by 2085. This on top of likely increased risks from unplanned development and mixing of pathogens. Hales et al, Lancet 2002; 268: 830-834

Urban infectious Disease: Diarrhoea Diarrhoea increases by 8% for each 1 degree centigrade increase in temperature. (Reproduced with permission from Checkley et al., Lancet, 2000)

Health vulnerabilities 4. Air pollution: How big are potential health co-benefits of improved energy policies? Outdoor Air pollution only: 700,000 deaths in 2020 (Davis et al, 1997) 64,000 deaths between 2000 to 2020, in Mexico City, Santiago, Sao Paulo and New York (Cifuentes et al, 2001) Not yet considered: Proportion of 1.2 million annual deaths from traffic accidents? Proportion of 1.7 million annual deaths from IAP? Proportion of 1.9 million annual deaths from physical inactivity?

Different routes are possible Atlanta Bangkok Singapore Houston Zurich Sao Paulo Washington Hong Kong London Alternative models are possible, that are likely to be healthier both in terms of the direct implications for health, but also in terms if environmental impacts. A third of car trips in Europe cover under 3 kilometres and half less than 5 kilometres, distances that can be covered by bicycle in 15–20 minutes or by brisk walking in 30–50 minutes (WHO 2004). Some cities have even banned or discouraged cycling because there are too many cars on the road (Barter 2003) Beijing Kenworthy, 2003

Protecting health while reducing Emissions Buildings Indoor air pollution Heat and cold protection Transport Air pollution Traffic injuries Physical inactivity Greenhouse Gas Emissions Industry Occupational risks, mining and transport Energy supply & conversion Occupational risks; Construction and transport Agriculture Nutrition, Water / vector-borne disease Waste Occupational, chemical

Adaptation to climate change: Conclusions Adaptation to climate change: Urbanization is occurring rapidly, changing nature of health vulnerabilities to climate variability and climate change Vulnerabilities can be reduced both by general development and health provision, and (sometimes) by targeted climate information Climate Change Mitigation: Policies concerning urban energy sources and use (e.g. transport), have strong direct links to globally important health impacts. Health considerations should be central in energy (=CC) decisions City-level actions are critical to the future of health adaptation to Climate Change and also to CC mitigation We know 1) That this is important for health 2) That it is becoming more important for health 3) There are many possible routes that especially developing economies could follow, and that these are important decisions directly from a health point of view We don’t yet have a comprehensive general agreement on: What the full range of implications are for health in the wide sense – e.g. community cohesion, mental well being. Depression expected to jump from 4th largest burden of disease in 1990 to 2nd in 2020. A review of good practice in cutting emissions, especially for cities at different stages of development- those that are designing transport systems almost from scratch (e.g. model cities designed by McDonough), versus those where it is being modified after the event (e.g. Bogota). Quantification of the effects of policy changes on health; e.g. just how much would the provision of better cycle lanes in London in the run up to the Olympics promote physical activity? BL: we know this is important for health, but we don't yet know what best practical advice to give people

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