The world's worst air: This week on Unreported World, while some of the air quality in the UK may be poor, imagine living in a place where air pollution can reach more than 100 times the accepted limit. That's the case in Ulaanbaatar the capital of Mongolia. Marcel Theroux reports on how the world's worst air is causing a public health disaster. This episode aired on 27/04/2018. // Subscribe to our channel for more Unreported World episodes null.