The director general of the World Health Organization has said air pollution is "one of the most pernicious threats" facing global public health today and is on a much bigger scale than HIV or Ebola, the BBC reported.

Dr Margaret Chan told the Today programme that poor air quality was having a disproportionate impact on the young and was linked to the deaths of hundreds of thousands of children each year. 

She said pollution kills 1.7 million children under the age of five each year due to diseases linked to smoke, indirect smoking, poor sanitation and uncleanliness.