13 of the world’s 20 most polluted cities are in India. The city that has topped the list is Byrnihat in Assam, followed by Delhi. The other cities in the top 20 belong to Pakistan (four), China (one), Kazakhstan (one) and Chad. India, which was at the third spot in 2023, became the fifth most polluted country in 2024. The report said India saw a 7 per cent decline in PM2.5 concentrations in 2024, averaging 50.6 micrograms per cubic metre. Overall, 35 per cent of the Indian cities reported annual PM1.5 levels exceeding 10 times the World Health Organization (WHO) limit of 5 microgramS per cubic metres. In Delhi, the air pollution has gone on to become even worse — with the annual average PM2,5 concentration rising from 102.4micrograms to 108.3Micrograms in 24 hours. In 2024, the average air pollution level in Delhi has risen from 104.4 microgrames to 106.3microgrames.