Four of the five most polluted cities in the world are now in India according to the latest survey conducted by the World Health Organisation (WHO) which released corroborative data on Thursday.
Zabol in Iran which is subject to dust storms in summer was found to have the worst air pollution followed by Gwalior, Allahabad, Patna and Raipur –all Indian cities.
Pollution is measured by the amount of Particulate Matter (PM) under 2.5 micrograms found in every cubic metre of air.
Tiny PM is known to cause strokes, heart diseases and lung cancer in the long run. According to WHO, three million of the seven million premature deaths that occur due to air pollution every year can be attributed to the quality of outdoor air.
Zabol clocked a PM 2.5 measure of 217 while Delhi had an annual average PM 2.5 measurement of 122, making it the ninth polluted city in the world. In 2014, Delhi was ranked first with a PM 2.5 reading of 153.
WHO experts however admit that though India does face a huge challenge, there are many countries like Africa which do not even have an effective monitoring system in place and so had to be left out.
The organisation surveyed 3000 urban areas this time which was almost double of what was included in the 2014 survey. Only two percent of the cities in poor countries have air quality on par with WHO standards while it was 44 percent in developed countries.
The other Indian cities in the top 20 are Ludhiana, Kanpur, Firozabad and Lucknow. Bengaluru is the most polluted south Indian city followed by Hyderabad.