The Global Burden of Disease Due to Urban Air Pollution: Estimates and Uncertainties Aaron Cohen Health Effects Institute

CRA project and WHR

Urban Air Pollution Working Group H Ross Anderson (Co-Chair) SGHMS U London Aaron Cohen (Co-Chair)Health Effects Institute Kersten GutschmidtWHO/Geneva Michal KrzyzanowskiWHO/Euro-Bonn Nino KünzliUniversity of Basel Bart OstroCalifornia Health Dept Kiran Dev PandeyWorld Bank Arden PopeBrigham Young Isabelle RomieuPAHO Jonathan SametJohns Hopkins Kirk SmithUC Berkeley

The Global Burden of Disease Due to Urban Air Pollution: Estimates and Uncertainties The Global Burden of Disease Comparative Risk AssessmentThe Global Burden of Disease Comparative Risk Assessment Estimating the Global Burden of Disease Due to Urban Air PollutionEstimating the Global Burden of Disease Due to Urban Air Pollution Magnitude and distribution of the attributable burdenMagnitude and distribution of the attributable burden Major sources of uncertaintyMajor sources of uncertainty Estimating the avoidable burdenEstimating the avoidable burden

Risk factors in CRA Child & maternal under-nutrition Childhood and maternal underweight Iron deficiency Vitamin A deficiency Zinc deficiency Other nutrition-related risks & inactivity High blood pressure High cholesterol Overweight and obesity Inadequate fruit and vegetable intake Physical inactivity Addictive substances Smoking and oral tobacco Alcohol Illicit drugs Sexual and reproductive health risks Unsafe sex Non-use and ineffective use of contraception Environmental risks Unsafe water, sanitation, and hygiene Urban air pollution Indoor smoke from solid fuels Lead exposure Climate change Occupational risks Risk factors for injury Carcinogens Airborne particulates Ergonomic stressors Noise Other selected risks to health Contaminated health care injections Child sexual abuse Distributions of risks by poverty

A: very low child and adult mortality B: low child and adult mortality C: low child, high adult D: high child, high adult E: high child, very high adult 14 WHO mortality sub-regions

Basic CRA framework and goals Risk factor levels current distribution counterfactual distribution(s) Disease burden Risk factor-disease relationships risk accumulation risk reversal Attributable burden in 2000 Avoidable burden in 2010 & 2020

Mortality and Burden of Disease Mortality = Numbers of Deaths Burden = Disability Adjusted Life Year or DALY DALY = YLL + YLD years of life lost because of premature death (YLLs) years of life lived with disability (YLDs) one DALY = one lost year of healthy life

Applying the CRA Methods to Urban Air Pollution Choice of indicator pollutant and estimation of ambient concentrations Choice of risk factor-disease relationships Calculation of disease burden

Estimated PM 10 Concentration in World Cities (pop >=100,000) PM 10 (µg/m 3 )

Population Distribution of Estimated PM 10 Levels for 3200 Cities Cohen et al 2004

American Cancer Society II Cohort 500, 000 adults followed 1982 – 1998 (Pope et al JAMA 2002) Random effects Cox proportional hazards model controlling for age, sex, race, smoking, education, marital status, body mass, alcohol, occupational exposure and diet RR per 10µg/m 3 PM RR95% CI Cardiopulmonary Lung Cancer

Alternative Scenarios for Burden of Disease Estimation for Urban Air Pollution

Percent change in mean daily number of child and infant deaths

1. Calculate region specific relative risk RR 2.5 = exp [CR * (X – 7.5)] where CR is slope of the C-R function ( β coefficient) and X is regional population weighted mean PM. 2. Calculate Attributable Fraction (AF) AF = P(RR-1) / [ P(RR-1)+1] where P is proportion exposed, i.e. proportion living in cities 3. Calculate attributable deaths and DALYs (AF * regional totals) Estimation of attributable deaths and DALYs

Estimated Burden of Urban Air Pollution Worldwide (95% confidence intervals)

Fraction of Deaths Attributable to Outdoor Urban Air Pollution by Region

Mortality attributable to leading risk factors Ezzati et al. 2002; WHO 2002

Burden of disease attributable to leading risk factors Ezzati et al. 2002; WHO 2002

Summary results for individual risks Substantial disease burden associated with risk factors such as under-nutrition, poor water and sanitation, and indoor air pollution remain, especially in the poorest developing countries Simultaneously risks from a number of factors such as smoking, alcohol, and obesity are becoming increasingly global Some risks, like urban air pollution and lack of contraception are major causes of burden in specific regions

The Burden of Disease Due to Air Pollution from Multiple Sources in Asia HEI 2004

Excess Deaths from Selected Environmental Factors

Uncertainties that we quantified Random variation in exposure and risk coefficient estimates Choice of PM 2.5 /PM 10 Choice of counterfactual level Choice of concentration-response function: coefficients and extrapolation

Sensitivity of Attributable Mortality Estimates

Uncertainties that we did not quantify Burden due to pollutants other than PM, e.g., ozone Burden in cities with populations <100 K Effects of exposure at finer spatial scales e.g., due to proximity to vehicular traffic Relative toxicity of PM from different sources Contribution of other potentially important health outcomes, e.g., LBW, infectious disease

Sources of fine particulate air pollution Delhi 2001 Georgia Tech (USA) 2004 Winter

Differential Toxicity of PM from Biomass and Fossil Fuels Mudway et al. Particle and Fibre Toxicology 2005

Spatial Analysis of Air Pollution and Mortality in Los Angeles ACS Cohort Jerrett et al Air pollution excess relative risks (per 10µg/m 3 ) for all-cause, IHD and lung cancer mortality 2-3 times as large in small-area (within- city) analyses as in inter-urban analyses reported by Pope et al and used for GBD estimates

Leading Causes of Mortality and Burden of Disease 2002 % Ischaemic heart disease 12.6 Cerebrovascular disease 9.7 Lower respiratory infections 6.8 HIV/AIDS 4.9 COPD 4.8 Perinatal conditions 4.3 Diarrhoeal diseases 3.2 Tuberculosis 2.7 Lung cancer 2.2 Malaria 2.2 Road traffic accidents 2.1 % Perinatal conditions 6.5 Lower respiratory infections 6.1 HIV/AIDS 5.7 Depression4.5 Diarrhoeal diseases 4.2 Ischaemic heart disease3.9 Cerebrovascular disease 3.3 Malaria 3.1 Road traffic accidents 2.6 Tuberculosis2.3 COPD 1.9 Mortality DALYs

Pediatrics 2005;115:

1.6 Million Deaths 8.9 Million Cases

Air Pollution and TB Modified from Baris and Ezzati 2004 Millions of Deaths (% in developing countries) % Global Burden of Disease (% in developing countries) Range of reported TB relative risk estimates Tuberculosis1.6 (>90%) 2.5 (>90%) Smoking4.8 (50%) 4.1 (>50%) (ever/never) Indoor Air Pollution 1.6 (>95%) 2.6 (>95%) (solid fuel use) Urban Outdoor Air Pollution 0.8 (>70%) 0.4 (>70%) None reported

Attributable and avoidable burden

What determines the health effects of air pollution as economies grow? Number of people in cities Sources of air pollution Emissions Air quality Susceptibility

An Increasingly Urban Population (data from UN/UN Centre for Human Settlements )

Development and Combustion of Fossil Fuels for Energy Generation/ Transportation (Data from International Energy Agency 2002 and M Walsh 2001)

UK SO 2 Emissions and Electricity Generation Figure from Williams ML 1999

A: very low child and adult mortality B: low child and adult mortality C: low child, high adult D: high child, high adult E: high child, very high adult Number of people at high CV risk (A Rogers 2005) 5 m 4 m 38 m 19 m 1 m 5 m 12 m 46 m 18 m 36 m 7 m 45 m 16 m 50 m >175 million people at 25%+ risk of a major CV event in the next decade, by WHO subregion

Reductions in Mortality in Dublin 72 Months Pre- vs. Post-1990 Ban on Coal Sales Clancy et al. Lancet 2002

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