Indore, India's cleanest city, fell to second place in the 2026 Clean Air Survey, losing its top spot to Lucknow by one point. The city's local administration attributed the decline to an increase in PM10 particles, which are ultra-fine airborne particles with a diameter of 10 micrometres or less. These particles, produced by vehicle exhaust, road dust, and industrial emissions, are known to enter the human respiratory system and pose health risks.

In the survey, Indore scored 197 out of 200 in the category of cities with a population of over 1 million, while Lucknow ranked first with 198 points. Jabalpur came third with 195 points, and Bhopal and Agra tied for fourth with 192 points each. Indore had previously topped the survey in 2025 with a perfect score of 200. The rankings were announced at the fifth edition of the Swachh Vayu Sarvekshan Awards on September 7, 2026.

Mayor Pushyamitra Bhargava of Indore told PTI that the city's PM10 levels were the reason for the drop. He stated, 'We scored one point lower than Lucknow in the survey due to (the city) lagging behind in PM10 particle standards.' Indore is noted for having the highest vehicle density in Madhya Pradesh, which the mayor said contributes to the pollution problem. He assured that measures to reduce pollution from traffic and industries, including PM10 particles, would be implemented throughout the year.

The city's municipal corporation data shows that PM10 levels in Indore declined by more than 15% compared to previous years, with an annual average of around 81 micrograms per cubic metre. However, this is still above the National Ambient Air Quality Standards (NAAQS), which set the annual average PM10 level at 60 micrograms per cubic metre for residential, industrial, and rural areas. The Air Quality Index (AQI) in Indore remained below 200 on more than 98% of the days during the evaluation period, which is considered 'Moderate' or better.

Officials said that to control dust, approximately 700 kilometres of roads in the city are swept daily with machines, and measures are being taken to dispose of construction waste. The mayor also announced plans to accelerate public awareness initiatives such as 'Red Light On, Engine Off' at traffic signals, promote electric vehicles, and operate e-buses to curb vehicular pollution. Additionally, efforts will be made to convert all garbage collection vehicles to electric ones and shift factories from diesel to green fuels like CNG.

The city has topped the National Sanitation Survey for eight consecutive years, indicating strong performance in other areas of urban management. However, the recent drop in the Clean Air Survey highlights the challenges Indore faces in maintaining its air quality standards. The exact reasons for the slight increase in PM10 levels and the effectiveness of the proposed measures remain to be seen.