HEALTH045transport, housing, water, sanitation and energyexpensive and carbon-intensive, and generatingexcessive pollution from both transport and homeheating. Unsustainable patterns of land use, moreover,are stimulating unhealthy lifestyles, insofar as citiesare increasingly inhospitable environments forwalking, cycling, and physical activity. There is thus anurgent need to focus attention of health anddevelopment policymakers on shared solutions. Along with the risks, there are, however, opportunities.Housing, transport and the wider built environmentdeserve far greater attention in the health sector andamong development agencies as entry points forcontrolling a range of diseases, and simultaneouslypromoting "greener" economic approaches todevelopment. The evidence is incontrovertible:"greener" development modes for housing, transportand land use not only can help reduce climate changeand support environmental sustainability, these modesare far healthier for people living in cities today.Greener built environments in cities will also help toreduce the burden of important communicablediseases, including diarrhoea related to unhealthywater and sanitation; vector borne diseases; childhoodpneumonia and tuberculosis: There is also a majoropportunity to link health more effectively toenvironment and development policies in the contextof "green economy" strategies being developed in thecontext of climate change mitigation, the Rio+20conference on sustainable development, attainment ofthe Millennium Development Goal, and other globalhealth, environment and development initiatives. MEETING THE HEALTH CHALLENGESOF THE FUTUREWhile infectious diseases and malnutrition continue toexact a huge toll on public health in the poorestpopulations, the fastest growing health threats are nowfrom non-communicable diseases, such ascardiovascular diseases, diabetes, cancer and chronicpulmonary diseases. These are now increasing rapidlyin developing as well as developed countries.For non-communicable diseases, as in other areas ofpublic health "Prevention is better than cure". In thecase of non-communicable diseases, the keys toprevention lie not only in behavioural change, but inenvironments that protect and promote health. Greengrowth strategies in transport, energy, housing andworkplaces can be a "win-win" for health, forsustainable development, environment and climatechange. For example, investment in public transit,walking and cycling systems, and "transit-friendly"urban housing and land use, are strongly associatedwith improved health and reduced cardiovasculardisease and obesity in studies from both developedand developing cities. A systematic review of obesityinterventions has found urban transport andenvironmental measures to be one of the mostsuccessful areas with the most convincing evidence ofeffectiveness - more so than behavioural measures ontheir own (WHO, 2009). Multiple cost-benefit studies of public health gainsfrom walking/cycling infrastructure show health gainsto be five times the investment cost (Cavill et al,2008). Two large epidemiological studies, in Shanghaiand in Copenhagen, found that people commuting bycycling have about a 30 per cent lower risk of dying ina year than less active commuters - even after injuryrisks and other risk factors were considered (Matthewset al, 2007; Andersen et al, 2000).In addition, some 1.2 million people die from non-communicable diseases related to urban air pollutionevery year. (WHO, 2009). Urban vehicle traffic, inparticular, is an important and growing cause of thisdisease burden. Transport is estimated to account forabout 25 per cent of health-damaging urban airBelow: Dr Maria Neira

pollutants in Europe, and as much as 60 to 70 percent in developing countries. WHO estimates thatreducing the level of one of the main components of airpollution (PM10) from 150 ?g /m3 - an order ofconcentration found in many large low- and middle-income cities -to 75 ?g /m3 would reduce short-termmortality from air pollution by 5 per cent, with largergains over longer time periods (WHO, 2006).Similar opportunities are available in the householdenergy sector in developing countries. ChronicObstructive Pulmonary Disease resulting from relianceupon energy-intensive and inefficient biomass andcoal stoves in developing countries causes over 1million premature deaths each year. A significantproportion of ischaemic heart disease and lung canceris also due to such stove use. These burdens falloverwhelmingly on women. Cleaner and greener biomass and biogas stovetechnologies now becoming available can prevent suchdeaths. Cleaner stoves also can very significantlyreduce environmentally-triggered childhoodpneumonia, one of the biggest killers of under-fives. Indeveloped countries greener and cleaner homeheating, insulation and ventilation can help controlallergies, asthma and other common respiratory NCDsas well as cardio-vascular disease associated with bothheat and cold extremes. All of these interventionsdeserve support as much by the health sector as by theenvironment sector.MANAGING THE TRANSITION TO AGREEN AND HEALTHY ECONOMYIn the long run, green growth, and the transition to amore sustainable and equitable economy, are key topopulation health. For at least the next few decades,however, we also need to protect people from theimpacts of the environmental degradation - to whichwe are already committed.Again, we are not doing as well as we should. Forexample, there is now clear evidence that climatechange is already worsening a range of health risks.This includes impacts on air (extreme air temperaturesand higher levels of some air pollutants), water(reduced quantity and quality of freshwater), food(reductions in rain fed agriculture), shelter (destructionfrom weather extremes), and freedom from disease(improved conditions for transmission of vector-borneand water-borne disease). These impacts areconcentrated on the poorest populations, and affectsome of the largest disease burdens, includingmalnutrition, diarrhea, and vector-borne diseases suchas malaria. WHO conservatively estimates that theclimate change that has occurred since the 1970salready causes over 140,000 excess deaths each year.To date, however, the international response is weak.While WHO, UNFCCC and the World Bank estimatethat climate change will result in an increase ofbetween US$2-12 billion in annual health costs by2020, current international support for healthadaptation to climate change is about 0.5 per cent ofthis figure. The Governments of the most vulnerablecountries have now clearly identified the criticalcomponents of health systems that need to bestrengthened to protect from climate change. As wemove towards a green economy, we also need to ensurethat we protect populations from the consequences ofpast pollution. SEEING THE BIGGER PICTUREIn the last few years, international attention hasfocused on global crises in climate, food security,energy prices, and finance. Each of these is a hugechallenge, including for health. However, addressing046HEALTHPhoto: shutterstock.com" "INVESTMENT INPUBLIC TRANSIT,WALKING AND CYCLING SYSTEMS,ARE STRONGLY ASSOCIATED WITHIMPROVED HEALTHAND REDUCEDCARDIOVASCULARDISEASE AND OBESITY