Ambient air pollution attributable deaths

Rationale: As part of a broader project to assess major risk factors to health, the burden of disease resulting from exposure to ambient (outdoor) air pollution was assessed. Ambient air pollution results from emissions from industrial activity, households, cars and trucks which are complex mixtures of air pollutants, many of which are harmful to health. Of all of these pollutants, fine particulate matter has the greatest effect on human health. In high-income countries, urban outdoor air pollution ranks in the top ten risk factors to health, and is the first environmental risk factors. Definition: The burden of disease attributable to ambient air pollution can be expressed as : Number of deaths Death rate (both crude and age-standardized) Number of disability-adjusted life years (DALYs) DALYs rate (both crude and age-standardized) Number of years life lost (YLLs) YLLs rate (both crude and age-standardized) Death (DALYs, or YLLs) rates are calculated by dividing the number of deaths by the total population (or indicated if a different population group is used, e.g. children under 5 years). Age-standardized rates adjust for differences in population age distribution by applying the observed age-specific mortality (or other health outcomes) rates for each population to a standard population. The age-standardized rates can therefore be used to compare the rates of countries without being affected by the differences in age distribution from country to country. Evidence from epidemiological studies have shown that exposure to ambient air pollution is linked, among others, to the important diseases taken into account in this estimate: Acute respiratory infectionsin young children (estimated under 5 years of age); Cerebrovascular diseases in adults (estimated above 25 years); Ischaemic heart diseases in adults (estimated above 25 years); Chronic obstructive pulmonary disease in adults (estimated above 25 years); and Lung cancer in adults (estimated above 25 years). Disaggregation: Age : <5 M&E Framework: Impact Method of estimation: Burden of disease is calculated by first combining information on the increased (or relative) risk of a disease resulting from exposure, with information on how widespread the exposure is in the population (in this case, the annual mean concentration of particulate matter to which the population is exposed). This allows calculation of the 'population attributable fraction' (PAF), which is the fraction of disease seen in a given population that can be attributed to the exposure, in this case the annual mean concentration of particulate matter. Applying this fraction to the total burden of disease (e.g. cardiopulmonary disease expressed as deaths or DALYs), gives the total number of deaths or DALYs that results from ambient air pollution. Method of estimation of global and regional aggregates: For deaths, DALYs and YLLs, national figures are summed. For the corresponding rates, the country estimates are summed according to the region of interest and divided by the corresponding regional population. Preferred data sources: Civil registration with complete coverage and medical certification of cause of death Special studies Comments: For a more detailed description of the methods, please consult: [http://www.who.int/phe/health_topics/outdoorair/databases/AAP_BoD_methods_March2014.pdf?ua=1] Main references: Brauer M, Amann M, Burnett RT, Cohen A, Dentener F, Ezzati M, et al. Exposure assessment for estimation of the global burden of disease attributable to outdoor air pollution. Environ Sci Technol. 2012;46(2):652-60. doi: 10.1021/es2025752. Burnett RT, Pope A, Ezzati M, Olives C, Lim SS, Mehta S, et al. An intgrated risk function for estimating the global burden of disease attributable to ambient fine particulate matter exposure. Environ Health Perspect. 2014(Advance publication 7 February 2014). http://dx.doi.org/10.1289/ehp.1307049. Lim SS, Vos T, Flaxman AD, Danaei G, Shibuya K, Adair-Rohani H, et al. A comparative risk assessment of burden of disease and injury attributable to 67 risk factors and risk factor clusters in 21 regions, 1990–2010: a systematic analysis for the Global Burden of Disease Study 2010. The Lancet. 2012;380(9859):2224-60. doi: 10.1016/S0140-6736(12)61766-8.