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2. United Nations Environment Programmehttps://www.unenvironment.org/explore-topics/climate-change/about-climate-change
3. Air Quality in Cities. A Global Challenge;Querol,2018
4. The Straits Times, 6 December 2018https://www.straitstimes.com/world/study-global-co2-emissions-to-hit-record-in-2018
5. Climate Change 2014: Impacts, Adaptation, and Vulnerability,2014