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 deathSpecial studiesComments: 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=1Main 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.

理由：作为一项旨在评估主要健康风险因素的更广泛项目的一部分，对暴露于环境（室外）空气污染所导致的疾病负担进行了评估。环境空气污染源自工业活动、家庭、汽车和卡车等排放源，这些排放源是复杂的空气污染物混合物，其中许多对健康有害。在这些污染物中，细颗粒物对人类健康的影响最为显著。在高收入国家，城市室外空气污染位列健康风险因素前十位，并且是首位环境风险因素。定义：环境空气污染导致的疾病负担可以表达为：死亡人数、死亡率（包括粗死亡率及年龄标准化死亡率）、残疾调整生命年（DALYs）数量、DALYs率（包括粗率和年龄标准化率）、预期寿命损失年（YLLs）数量、YLLs率（包括粗率和年龄标准化率）。死亡（DALYs或YLLs）率通过将死亡人数除以总人口（或若使用其他人口群体，则需特别说明，例如5岁以下儿童）计算得出。年龄标准化率通过将每个群体的观察到的年龄特异性死亡率（或其他健康结果）率应用于标准人口，以调整人口年龄分布的差异。因此，年龄标准化率可以用于比较各国之间的率，而不会受到各国年龄分布差异的影响。流行病学研究的证据表明，暴露于环境空气污染与以下重要疾病密切相关：幼儿（估计年龄在5岁以下）的急性呼吸道感染；成人（估计年龄在25岁以上）的脑血管疾病；成人（估计年龄在25岁以上）的缺血性心脏病；成人（估计年龄在25岁以上）的慢性阻塞性肺疾病；以及成人（估计年龄在25岁以上）的肺癌。分解：年龄：＜5岁
M&E 框架：影响
估计方法：疾病负担的计算首先结合了由于暴露而导致的疾病（或相对）风险增加的信息，以及该暴露在人群中的普遍程度的信息（在本例中，为人群所暴露的颗粒物年浓度平均值）。这允许计算“人群归因分数”（PAF），即特定人群中观察到的疾病中可以归因于暴露（在本例中为颗粒物年浓度平均值）的部分。将此分数应用于总的疾病负担（例如以死亡或DALYs表示的心肺疾病），可得出由环境空气污染导致的死亡人数或DALYs总数。全球和区域总和的估计方法：对于死亡、DALYs和YLLs，将国家数据相加。对于相应的率，根据感兴趣的区域将国家估计值相加，然后除以相应的区域人口。推荐数据来源：覆盖范围完整的民事登记和死亡原因医学证明、特别研究
注释：欲了解方法的更详细描述，请参阅：http://www.who.int/phe/health_topics/outdoorair/databases/AAP_BoD_methods_March2014.pdf?ua=1
主要参考文献：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.