A United Nations report published on Wednesday said in 2016 an estimated 4.2 million people died as a result of high levels of ambient air pollution. In 2016 91 per cent of the urban population worldwide were breathing air that did not meet the World Health Organization Air Quality Guidelines value for particulate matter (PM 2.5); more than half were exposed to air pollution levels at least 2.5 times higher than that safety standard said the 2018 Sustainable Development Goals Report launched at the United Nations headquarters in New York. Read: Outdoor pollution behind 6% of disease burden Many cities around