It comes as no surprise that Delhi, the capital city of India, is the most polluted city in the country. Meanwhile, Patna, the capital of Bihar, has the second highest levels of air pollution.
The cleanest air in the country is enjoyed by the residents of Aizawl in Mizoram in northeast India.
These are the findings of the latest assessment of air quality data published by the Central Pollution Control Board (CPCB). The analysis has been jointly released by Climate Trends, a research-based consulting initiative that focuses on environment and climate change; and Respirer Living Sciences, a climate tech start-up based in Maharashtra.
According to a daily bulletin from the CPCB, though between October 2022 and September 2023, the air quality of Delhi has ‘improved marginally’, it continued to top the list of the 10 most polluted cities in the country.
As per the report, Delhi has recorded a PM 2.5 (particles less than 2.5 micrometres in diameter that pose the greatest threat to health) level of 100.1 µg/m³ (micrograms per metre cube) from October 1, 2022, to September 30, 2023. This is marginally better than the 103.9 µg/m³ recorded from October 2021 to September 2022 but New Delhi is still the most polluted city in the country.
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Patna came a close second on the list with a PM 2.5 concentration of 99.7 µg/m³, followed by Muzaffarpur in Bihar with a level of 95.4 µg/m³ in the same time frame.
Meanwhile, Faridabad, Noida, Ghaziabad, and Meerut, which are all part of the National Capital Region of Delhi, found themselves on the list of top polluted cities too.
The CPCB data shows that the PM 2.5 levels in Faridabad, Ghaziabad, Noida and Meerut have come down compared to the figures from October 2021 to September 2022, with the largest percentage fall of 25 per cent being recorded in Ghaziabad.
The CPCB data is for 131 non-attainment cities (NAC) identified by the National Clean Air Programme (NCAP) of the Indian government. Cities are declared non- attainment if over a five-year period they consistently do not meet the National Ambient Air Quality Standards (NAAQS) for PM 10 (particulate matter that is 10 microns or less in diameter) or NO2 (Nitrogen Dioxide).
The cities where the monitors recorded data for more than 70 per cent of the time for both years were considered for analysis. Delhi was found to be the most polluted among 73 cities where the monitor uptime was more than 70 per cent.
Last year, in 2022, between October to December, PM2.5 levels dropped in Delhi, Faridabad, Noida, Ghaziabad, and Meerut in the NCR compared to the same period in 2021. While this shows an improvement in air quality, the report cautioned, “How much of this was due to climatic factors (rain, wind) and how much due to policy intervention is a matter of deeper study.”
