Delhi remains among world's most polluted cities; Kolkata, Mumbai are other Indian metros in the top 10 list

Amid raising air quality concerns in Delhi and with Diwali around the corner, the State is set to announce Graded Response Action Plan stage-1 restrictions.

Delhi, which struggles with very poor air quality (AQI of over 200), has been ranked second in the 10 most polluted cities in the world, based on the Air Quality Index (AQI) ranking. Apart from the national capital, Kolkata and Mumbai are the two other Indian cities in the top-10 list.

Amid raising air quality concerns in Delhi and with Diwali around the corner, the State is set to announce Graded Response Action Plan (GRAP) stage-1 restrictions.

For the seventh year, Delhi has been the most polluted national capital in the world. Delhi records 11.5 per cent of its total annual deaths due to short-term exposure to PM2.5 pollution, according to a study.

AQI + US refers to the Air Quality Index used in the United States, which is calculated using measurements of pollutants such as particulate matter (PM), ozone, carbon monoxide, sulfur dioxide, and nitrogen dioxide.

This year, the national capital took new initiatives to bring the air pollution under control.

• The launch of Air Pollution Mitigation Plan 2025 which mandates deployment of 2,300 electric autos at metro stations, installation of mist sprayers at 13 pollution hotspots and audit of PUCC centers every six months.

• In June 2025, IIT Kanpur submitted plans to induce artificial rain for the first time in Delhi. The aim is to reduce air pollution with cloud seeding technique. This is yet to be implemented.

• Earlier this year, Delhi Environment Minister Manjinder Singh Sirsa instructed officials to crack down on sources of pollution and ensure time-bound implementation of mitigation measures, including water sprinklers and anti-smog guns, at major construction sites and pollution hotspots.

Delhi, Kolkata and  Mumbai are among the 10 most polluted cities in the world, as per the Air Quality Index ranking.

Despite these measures, challenges to reduce air pollution remain in Delhi.

Kolkata

With an AQI of 161, Kolkata is the second most polluted metro in India. AQI of 161 could lead to respiratory diseases, including fatal ones in some.

The authorities have spent nearly half of the Rs 960 crore funds allocated under the National Clean Air Programme in the last five years to mitigate air pollution in the city.

Mumbai

Mumbai's AQI at 148 falls under the 'moderate or satisfactory' category. After the last few weeks of irregular and heavy rainfall, the city has seen a drop in the AQI level, bringing relief to its residents.

According to the air quality data released in August 2025, the air in India is eight times more toxic than the World Health Organization's safe air quality standard.