India has 13 of world’s 20 most polluted cities; Delhi worst capital for 6th year, nation ranks 5th globally

India has dominated the World Air Quality Report 2024, with 13 of the world's 20 most polluted cities located within its borders. Byrnihat in Assam has been named the most polluted city globally, recording a PM2.5 concentration of 128.2 micrograms per cubic metre, which is over 25 times the WHO’s safe limit of 5 micrograms per cubic metre. Delhi remains the most polluted capital city in the world for the sixth consecutive year, with an annual PM2.5 level of 91.6 micrograms per cubic metre, almost unchanged from 2023.

Despite India witnessing a 7% decline in its average PM2.5 levels, from 54.4 micrograms per cubic metre in 2023 to 50.6 in 2024, air pollution continues to be a critical issue. 35% of Indian cities reported PM2.5 concentrations exceeding 10 times the WHO’s limit. The report ranks India as the fifth most polluted country globally, dropping from third place in 2023. The four countries with worse air pollution are Chad, Bangladesh, Pakistan, and the Democratic Republic of Congo.

Apart from Byrnihat and Delhi, the other highly polluted Indian cities in the top 20 include Mullanpur (Punjab), Faridabad, Loni, Gurugram, Ganganagar, Greater Noida, Bhiwadi, Muzaffarnagar, Hanumangarh, and Noida. The air quality in these cities is primarily impacted by vehicular emissions, industrial pollution, stubble burning, and construction dust, along with adverse meteorological conditions that trap pollutants, especially during winter months.

The report highlights that long-term exposure to PM2.5 pollution has severe health consequences, including respiratory diseases, heart ailments, and reduced life expectancy. A Lancet Planetary Health study previously estimated that 1.5 million deaths in India each year from 2009 to 2019 were linked to prolonged PM2.5 exposure. Former WHO chief scientist Soumya Swaminathan stated, "We have the data; now we need action. Some solutions are easy, like replacing biomass with LPG. The first cylinder is free, but the poorest families should receive higher subsidies. This will improve their health and reduce outdoor air pollution."

In addition to household pollution control, Swaminathan emphasized the need for expanding public transport, imposing penalties on certain vehicles, and ensuring strict enforcement of industrial emission laws. She said, "Industries and construction sites must comply with regulations and install equipment to cut emissions instead of taking shortcuts." The report also points out that while China, once a major contributor to air pollution, has reduced its national PM2.5 levels from 32.5 to 31 micrograms per cubic metre, India's progress in air quality control remains insufficient.

Air pollution continues to be a significant environmental and health crisis, with data gaps posing a challenge to effective policymaking. The report notes that Iran and Afghanistan did not feature due to a lack of data, while several Southeast Asian nations still have major gaps in government-led air quality monitoring initiatives. The issue is likely to be further compounded as the US recently announced it will stop sharing air quality data collected from its embassies and consulates worldwide due to funding constraints.