Clean Air Day 2026 puts India’s air pollution challenge back in focus as cities confront the health and environmental costs of particulate pollution. Observed globally as the International Day of Clean Air for
Blue Skies , September 7 is also marked in India as Swachh Vayu Diwas. The day highlights the need for cleaner transport, better waste management, dust control, industrial compliance and stronger public participation.
India’s latest government data offers a mixed picture: 108 of 130 cities covered by the National Clean Air Programme recorded lower annual PM10 concentrations in 2025-26 than their 2017-18 baseline, while 22 cities moved in the opposite direction.
Clean Air Day 2026: What the latest data says about Indian cities
India’s clean-air story in 2026 is one of measurable progress, but also significant gaps.
According to the latest data from the Ministry of Environment, Forest and Climate Change, 108 of the 130 cities covered under the National Clean Air Programme (NCAP) recorded a reduction in annual PM10 concentrations in FY 2025-26 compared with 2017-18.
Of these, 72 cities achieved reductions of more than 20%, while 26 recorded reductions of more than 40%.
But there is an important distinction to make: a city recording lower PM10 than its 2017-18 baseline does not necessarily mean its air is now “clean”.
The government says only 14 NCAP cities met the annual PM10 National Ambient Air Quality Standard of 60 µg/m³ in 2025-26, compared with six cities in 2017-18.
That means readers need two separate benchmarks — one to determine whether pollution has improved or worsened, and another to determine whether the current annual concentration meets the national standard.
How to read India’s air-quality numbers
Before comparing the cities, it is important to understand the benchmark used in the government data.
For annual PM10 pollution, India’s National Ambient Air Quality Standard is 60 micrograms per cubic metre (µg/m³).
60 µg/m³ or below: The city’s annual PM10 concentration meets the national standard.
Above 60 µg/m³: The annual PM10 concentration exceeds the national standard.
PM10 falls from the 2017-18 baseline: The city has improved compared with its baseline, even if its current level remains above 60 µg/m³.
PM10 rises from the 2017-18 baseline: The city has worsened compared with its baseline.
For example, Kohima’s 2025-26 PM10 concentration of 47 µg/m³ is below the national annual standard, while Delhi’s 200 µg/m³ remains substantially above it, even though Delhi recorded a reduction from its 2017-18 baseline.
It is also important not to confuse annual PM10 concentration with AQI. AQI is a short-term air-quality indicator. Under the CPCB’s National Air Quality Index, 0-50 is Good, 51-100 Satisfactory, 101-200 Moderate, 201-300 Poor, 301-400 Very Poor and 401-500 Severe.
Which Indian cities improved?
The government’s FY 2025-26 assessment shows substantial reductions in annual PM10 concentrations in several cities compared with their 2017-18 baseline.
Among the cities showing some of the largest reductions:
These figures highlight an important point: improvement and compliance are not the same thing.
For instance, Delhi’s annual PM10 concentration fell substantially compared with its baseline, but its 2025-26 concentration of 200 µg/m³ was still well above the national annual standard of 60 µg/m³.
Similarly, some cities that achieved sizeable percentage reductions continued to record annual PM10 levels above the prescribed standard.
Which Indian cities worsened?
While 108 cities recorded lower annual PM10 concentrations than their 2017-18 baseline, 22 of the 130 NCAP cities recorded increases in 2025-26.
Some notable increases include:
Visakhapatnam sees the sharpest increase
Among these cities, Visakhapatnam stands out for the size of its increase. Its annual PM10 concentration rose from 76 µg/m³ in 2017-18 to 119 µg/m³ in 2025-26, representing an increase of more than 56%.
The figure is significant because it shows why India’s clean-air progress cannot be judged simply by looking at the number of cities receiving clean-air funding or participating in NCAP. Pollution trends remain uneven across cities, and some locations have moved backwards against their baseline.
What about Delhi, Mumbai, Pune and Hyderabad?
The government’s latest data also provides PM2.5 figures for several major Indian cities.
In FY 2025-26, Hyderabad recorded an annual PM2.5 concentration of 34 µg/m³ and Surat 32 µg/m³, both below the national annual PM2.5 standard of 40 µg/m³.
- Mumbai recorded 33 µg/m³, while Pune recorded 41 µg/m³, marginally above the standard.
- Delhi remained considerably higher, with an annual PM2.5 concentration of 102 µg/m³.
This again demonstrates why an article about India’s air quality needs to distinguish between PM10, PM2.5 and AQI. They are related, but they are not interchangeable measures.
AQI vs PM10: Why the distinction matters
For a reader checking the air quality of their city on a particular day, the AQI is the more useful short-term indicator.
The CPCB’s AQI categories are:
AQI Category
- 0-50 Good
- 51-100 Satisfactory
- 101-200 Moderate
- 201-300 Poor
- 301-400 Very Poor
- 401-500 Severe
The NCAP comparison discussed here, however, is based on annual PM10 concentrations compared with the 2017-18 baseline.
Therefore, a city can have improved annual PM10 levels while still having poor air on individual days, particularly during periods of unfavourable weather, increased emissions or seasonal pollution episodes.
India’s bigger clean-air picture
The latest figures suggest that India’s clean-air programme is producing measurable gains, but progress remains uneven.
The government says ₹16,423.56 crore in performance-based incentive grants has been released to 130 cities for implementing clean-air action plans between FY 2019-20 and FY 2025-26.
The National Clean Air Programme addresses pollution sources including road and soil dust, vehicle emissions, waste burning, construction activity and industrial pollution.
For cities where annual PM10 has increased, the challenge is therefore not simply to improve the AQI on a handful of favourable days. The bigger objective is to achieve sustained reductions in annual particulate pollution.
What Clean Air Day 2026 tells us
The latest government data presents a mixed but important picture.
108 of 130 NCAP cities recorded a reduction in annual PM10 concentrations compared with their 2017-18 baseline, while 22 recorded increases. At the same time, only 14 cities met the annual PM10 standard of 60 µg/m³ in 2025-26.
In other words, India has made measurable progress, but a reduction in pollution does not automatically mean a city has achieved clean air.
The simplest way to interpret the numbers is:
- Lower than the city’s 2017-18 PM10 level = improvement.
- Higher than its 2017-18 level = worsening.
- 60 µg/m³ or below = meets the annual national PM10 standard.
- Above 60 µg/m³ = exceeds the annual national PM10 standard.
That distinction is perhaps the most important takeaway from Clean Air Day 2026: India’s cities are moving at different speeds, and the next challenge is turning reductions into consistently safe air.
