Ambient air pollution-induced health risk for children worldwide
Authors: Jae Young Lee, Ho Kim
Journal: The Lancet Planetary Health (2018)

Air pollution has severe effects on health, including mortality, and researchers have been actively attempting to work out the nature of this relationship. According to The Lancet Commission on pollution and health,1Landrigan PJ Fuller R Acosta NJR et al.The Lancet commission on pollution and health.Lancet. 2018; 391: 462-512Summary Full Text Full Text PDF PubMed Scopus (1962) Google Scholar ambient air pollution-induced excess mortality exceeded 4·5 million worldwide in 2015. By comparison, this mortality toll is more than two-thirds of the 6·4 million deaths caused by tobacco smoking.1Landrigan PJ Fuller R Acosta NJR et al.The Lancet commission on pollution and health.Lancet. 2018; 391: 462-512Summary Full Text Full Text PDF PubMed Scopus (1962) Google Scholar, 2GBD 2015 Risk Factor CollaboratorsGlobal, regional, and national comparative risk assessment of 79 behavioural, environmental and occupational, and metabolic risks or clusters of risks, 1990–2015: a systematic analysis for the Global Burden of Disease Study 2015.Lancet. 2016; 388: 1659-1724Summary Full Text Full Text PDF PubMed Scopus (2838) Google Scholar, 3GBD 2015 LRI CollaboratorsEstimates of the global, regional, and national morbidity, mortality, and aetiologies of lower respiratory tract infections in 195 countries: a systematic analysis for the Global Burden of Disease Study 2015.Lancet Infect Dis. 2017; 17: 1133-1161Summary Full Text Full Text PDF PubMed Scopus (411) Google Scholar In particular, exposure to ambient air pollution is extremely harmful to young children, as it can increase their risk of mortality through lower respiratory tract infections (LRIs).1Landrigan PJ Fuller R Acosta NJR et al.The Lancet commission on pollution and health.Lancet. 2018; 391: 462-512Summary Full Text Full Text PDF PubMed Scopus (1962) Google Scholar, 3GBD 2015 LRI CollaboratorsEstimates of the global, regional, and national morbidity, mortality, and aetiologies of lower respiratory tract infections in 195 countries: a systematic analysis for the Global Burden of Disease Study 2015.Lancet Infect Dis. 2017; 17: 1133-1161Summary Full Text Full Text PDF PubMed Scopus (411) Google Scholar, 4Zhu L Ge X Chen Y et al.Short-term effects of ambient air pollution and childhood lower respiratory diseases.Sci Reports. 2017; 7: 4414Crossref PubMed Scopus (43) Google Scholar, 5Gascon M Sunyer J Air pollution and respiratory health in childhood.Arch Bronconeumol. 2015; 51: 371-372Crossref PubMed Google Scholar, 6Jassal M Pediatric asthma and ambient pollutant levels in industrializing nations.Int Health. 2015; 7: 7-15Crossref PubMed Scopus (26) Google Scholar According to WHO estimates and the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD), about 1 million children younger than 5 years died from LRIs in 2015, which can be partly attributed to air pollution exposure in combination with poor nutrition and health care.3GBD 2015 LRI CollaboratorsEstimates of the global, regional, and national morbidity, mortality, and aetiologies of lower respiratory tract infections in 195 countries: a systematic analysis for the Global Burden of Disease Study 2015.Lancet Infect Dis. 2017; 17: 1133-1161Summary Full Text Full Text PDF PubMed Scopus (411) Google Scholar, 7WHO. Estimates for 2000–2016. http://www.who.int/healthinfo/global_burden_disease/estimates/en/index3.html (accessed June 9, 2018).Google Scholar In The Lancet Planetary Health, Jos Lelieveld and colleagues examined ambient air pollution-induced excess mortality between 2010 and 2015, focusing on children younger than 5 years.8Lelieveld J Haines A Pozzer A Age dependent health risk from ambient air pollution: childhood mortality in middle and low-income countries.Lancet Planet Health. 2018; 2: e292-e300Scopus (71) Google Scholar The researchers used a general circulation model called EMAC to estimate the concentrations of ambient air pollutants such as PM2·5 and ozone. They then estimated the air pollution attributable fraction of mortality based on integrated exposure-response functions. As well as excess mortality, the investigators presented the corresponding years of life lost (YLL) due to premature mortality. Because YLLs more heavily weight deaths at younger ages, they are a suitable metric to express the effect of air pollution on childhood mortality. For a detailed analysis, the excess mortality and YLLs were divided into disease categories and geographic locations. Lelieveld and colleagues found that ambient air pollution-induced under-5 mortality accounted for 5% (246 000 deaths) of the total ambient air pollution-induced mortality (4·55 million deaths), and that YLLs from children younger than 5 years accounted for 18% (22·4 million years) of the total YLLs due to exposure to air pollution (122 million). Given that children younger than 5 years constitute 9% of the total global population, this subpopulation faces roughly twice as much of a potential loss of life than the remaining population. Additionally, the authors analysed this excess mortality by disease categories and found that LRIs were the main cause of death in children. Of the total ambient air pollution-induced under-5 mortality, 237 000 (96%) deaths were due to LRIs. Similarly, of the total YLLs due to air pollution in children younger than 5 years, 96% were due to LRIs. Breaking down the results by geographic location, 99% (235 000 deaths) of under-5 mortality occurred in Africa (128 000 [54%]) and Asia (107 000 [45%]). Of the African portion of this burden, 40% of deaths (n=51 000) were in Nigeria, whereas in Asia, 48% of deaths (n=51 000) were in India. These two countries both have low incomes and large populations. Finally, the authors found that between 2010 and 2015, ambient air pollution induced under-5 mortality from LRIs fell by 22% (from 302 000 to 237 000 deaths per year), whereas the under-5 population only decreased by 4%. This large decrease in under-5 mortality is probably largely driven by improved health care and nutrition for children, especially in India, where under-5 mortality fell by 34% (from about 77 000 to 51 000 deaths per year). Although the researchers calculated 95% CIs for their findings to show statistical uncertainties, there might be other sources of uncertainties that are not captured by the confidence intervals. These other sources would include unaccounted confounding factors and uncertainties in the epidemiological data, such as misclassification of disease. While under-5 mortality due to air pollution-attributable LRIs dropped by 22%, this disease category still accounted for 18% of total air pollution-related YLLs in 2015. As such, further action must be taken. One promising aspect of the present study's findings is that, since under-5 mortality is dominated by LRIs and occurs almost exclusively in Africa and Asia, a targeted effort to improve nutrition and health care for children in low-income countries in Africa and Asia could be a very effective way to reduce under-5 mortality. In this regard, the work done by Lelieveld and colleagues will be a good reference for people involved in relief and aid activities. We declare no competing interests. This Comment was financially supported by the Global Research Lab (K21004000001-10A0500-00710) through the National Research Foundation of Korea, funded by the Ministry of Science,(Information and Communication Technologies, and Future Planning, as well as by the Korean Ministry of Environment under the Climate Change Correspondence Program (project number 2014001310007). Age-dependent health risk from ambient air pollution: a modelling and data analysis of childhood mortality in middle-income and low-income countriesMost child deaths due to AAP-LRIs occur in low-income countries in Africa and Asia. A three-pronged strategy is needed to reduce the health effects of ambient air pollution in children: aggressive reduction of air pollution levels, improvements in nutrition, and enhanced treatment of air pollution-related health outcomes. Full-Text PDF Open Access