Delhi recorded consistently high pollution levels, with an annual average PM2.5 concentration of 91.6 micrograms per cubic metre. The World Air Quality Report 2024 by Swiss air quality technology company IQAir said Delhi remains the most polluted capital city globally. India ranked as the world’s fifth most polluted country in 2024, down from third in 2023. The 13 Indian cities in the top 20 most polluted cities are Byrnihat, Delhi, Mullanpur (Punjab), Faridabad, Loni, New Delhi, Gurugram, Ganganagar, Greater Noida, Bhiwadi, Muzaffarnagar, Hanumangarh and Noida. Air pollution remains a serious health risk in India, reducing life expectancy by an estimated 5.2 years. Sources include vehicle exhaust, industrial emissions and the burning of wood or crop waste, according to a Lancet Planetary Health study published last year. About 1.5 million deaths in India every year from 2009 to 2019 were potentially linked to long-term exposure to PM1.5 pollution.