studies and pollution]
Hindustan Times, Delhi | By Anonna Dutt
UPDATED ON AUG 28, 2018 11:22 AM IST
The world’s top 20 most polluted cities, according to the World Health Organization’s (WHO) database, are in developing countries. Almost all the cities in low- and middle-income countries with more than 1,00,000 residents fail to meet WHO air quality guidelines.