Interplay of Climate Change and Air Pollution- Projection of the Under-5 Mortality Attributable to Ambient Particulate Matter (Pm2.5) in South Asia

Abstract

Ambient fine particulate matter (PM2.5) pollution is a leading health risk factor for children under 5 years especially in developing countries. South Asia is a PM2.5 hotspot, where climate change, a potential factor affecting PM2.5 pollution, adds a major challenge. However, limited evidence is available on under-5 mortality attributable to PM2.5 under different climate change scenarios. This study aimed to project under-5 mortality attributable to long-term exposure to ambient PM2.5 under seven air pollution and climate change mitigation scenarios in South Asia. We used a log-linear concentration-risk function from a previous review to estimate under-5 mortality attributable to ambient PM2.5. This risk function, with a theoretical minimum risk exposure level of 2.4 µg/m3, was linked to gridded annual PM2.5 concentrations from atmospheric modeling to estimate under-5 mortality from 2010 to 2049 under different climate change mitigation scenarios. The scenarios were developed from the Aim/Endues global model based on end-of-pipe (removing the emission of air pollutant at the source, EoP)  and  2°C target measures. Our results showed that, in 2010–2014, about 306.8 thousand under-5 deaths attributable to PM2.5 occurred in South Asia under the Reference (business as usual) scenario. The number of deaths was projected to increase in 2045–2049 by 36.6% under the same scenario and 7.7% under the scenario where EoP measures would be partially implemented by developing countries (EoPmid), and was projected to decrease under other scenarios, with the most significant decrease (81.2%) under the scenario where EoP measures would be fully enhanced by all countries along with the measures to achieve 2°C target (EoPmaxCCSBLD) across South Asia. Country-specific estimates of under-5 mortality varied by country. The current emission control strategy would not be sufficient to reduce the number of deaths in South Asia. Robust climate change mitigation and air pollution control policy implementation is required.

Keywords: Under-5 mortality, ambient PM2.5, Climate change, mitigation scenarios, South Asia