Delhi was the most polluted city in India in 2022 with PM 2.5 levels more than double the safe limit and the third highest average PM10 concentration, according to an analysis of Central Pollution Control Board data.

PM2.5 pollution in the national capital has reduced by over 7 per cent in four years, from 108 micrograms per cubic metre in 2019 to 99.71 micrograms per cubic metre in 2022, the report by NCAP Tracker said.

NCAP Tracker is a joint project of news portal Carbon Copy and a Maharashtra-based start-up 'Respirer Living Sciences' and is designed to track India's progress in achieving clean air targets.

The Centre launched the National Clean Air Programme on January 10, 2019 to reduce PM2.5 and PM10 levels in 102 cities by 20 per cent to 30 per cent by 2024 (with 2017 being the base year). Some more cities were added to the list, while some were dropped subsequently.

Now there are 131 cities which are called non-attainment cities, as they did not meet the national ambient air quality standards (NAAQS) for the period of 2011-15 under the National Air Quality Monitoring Programme.

In September 2022, the government set a new target of a 40 per cent reduction in particulate matter concentration by 2026.

Among the most polluted cities with respect to PM2.5 levels, Delhi (99.71 micrograms per cubic metre) ranked first, Haryana's Faridabad (95.64 micrograms per cubic metre) ranked second and Uttar Pradesh's Ghaziabad (91.25 micrograms per cubic metre) third, according to the analysis of CPCB data.

PM2.5 is tiny particulate matter that is less than 2.5 microns in diameter and can enter the lungs and bloodstream.

Ghaziabad (217.57 micrograms per cubic metre) was the most polluted non-attainment city in the country in terms of PM10 levels, while Faridabad (215.39 micrograms per cubic metre) ranked second and Delhi (213.23 micrograms per cubic metre) stood third.

In 2021, Ghaziabad was the most polluted with respect to PM2.5 levels while it ranked third in terms of PM10 levels.

The country's current annual average safe limits for PM2.5 and PM10 are 40 micrograms per cubic metre and 60 micrograms per cubic metre, respectively.

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