Which city has been named as the world’s most polluted city, as per recently released urban air quality database of World Health Organization (WHO)?

Zabol
As per recently released urban air quality database of World Health Organization (WHO), “Zabol” an eastern Iranian city, has been ranked first among the most polluted cities in the world. Based on readings of fine particulate pollution in the air (PM 2.5), the four Indian cities are among the world’s 10 most polluted cities. These are Gwalior (2nd), Allahabad (3rd) , Patna (6th), and Raipur (7th). The National Capital of India “New Delhi” has been ranked 11th among 3,000 cities in 103 countries in terms of PM 2.5 and 25th in terms of PM 10 (coarse pollution particles) levels. In 2014, New Delhi was ranked the most polluted city.