Between 2015 and to date, based on the data availability, the AQI value was above 100 (Moderate) for 83% of the total recorded days for Delhi. This is closely followed by Ghaziabad at 81%, Gurugram and Noida at 79%, Jodhpur at 77%, Muzaffarnagar at 75%, and Patna at 71%. Data also shows that Hyderabad & Bengaluru did not record AQI of above 200 in the last many years.
Air pollution is one of the most pressing challenges facing the world, with significant economic and health consequences. According to the United Nations Environment Programme (UNEP), it costs the global economy $8.1 trillion each year, accounting for about 6.1% of global GDP. In 2021, 99% of the global population lived in areas where air quality failed to meet the World Health Organization’s updated guidelines, making air pollution a major health threat linked to one in nine deaths worldwide. On average, exposure to harmful PM2.5 particles shortened global life expectancy by about one year and eight months in 2021.
In India, the air pollution crisis is particularly severe. The 2023 World Air Quality Report reveals that 96% of the country’s 1.3 billion people live with air quality far beyond the WHO’s safe thresholds. UNEP reports that India’s annual mean exposure to PM2.5 is 48.4 µg/m³—nearly ten times higher than the recommended levels.
As winter arrives, the familiar haze of toxic air pollution blankets India. New Delhi, the Capital of India recorded alarming levels of air pollution on 23 October 2024. Against this backdrop, we examine the trends in the Air Quality Index (AQI) across major Indian cities. This story serves as an update to our previous analysis, which you can read here.
The analysis relies on data from Dataful, which provides daily averages based on 24-hour AQI measurements recorded at 4 PM each day. This dataset spans from 2015 to till date, offering a comprehensive view of air quality trends over nearly a decade.
Delhi recorded above 100 AQI for 83% of the days between Apr 2015 till date
Broadly, there are six Air Quality Index (AQI) categories.
- 0-50 is considered Good
- 51-100 as Satisfactory
- 101-200 as Moderate
- 201-300 as Poor
- 301-400 as Very Poor
- above 400, 401-500 is considered as Severe.
Among the cities of India, between 2015 and till date, based on the data availability, the AQI value was above 100 for 83% of the total recorded days for Delhi. This is closely followed by Ghaziabad at 81%, Gurugram and Noida at 79%, Jodhpur at 77%, Muzaffarnagar at 75%, and Patna at 71%. Major metropolitan cities like Bengaluru saw 18% of all recorded days above 100, while Chennai saw 25%, Hyderabad saw 36%, Kolkata at 40%, Mumbai at 43%, and Pune at 48%.
Pollution in North India is both attributable to the geography of the region and increasing emissions. One can see that the major polluted cities are located in the Indo-Gangetic plain.
Increasing frequency of days with AQI above 200 in recent years for major cities
In our previous analysis, we noted that Bengaluru and Hyderabad had never recorded an AQI above 200. The same trend continued even in 2024. In contrast, Pune saw a significant increase, jumping from an average of seven days per year before 2023 to 16 days in 2023. A similar trend was observed in Vishakhapatnam, which reported 41 days with an AQI above 200 in 2023. Patna experienced a significant rise in pollution levels in 2023, with 163 days registering an AQI above 200—the joint highest with 2022 count since 2020.
Meanwhile, cities like Ahmedabad, Jodhpur and Kolkata have seen improvements. In 2023, these cities recorded their lowest number of days with AQI above 200 since 2020—Ahmedabad with 3 days, Jodhpur with 26 days and Kolkata with 46 days.
Between 01 January 2024 and 24 October 2024, Cities like Pune, Mumbai, Hyderabad, and Bengaluru did not record a single day with AQI levels above 200, while Chennai recorded one day of AQI above 200. Cities like Noida, Muzaffarnagar, Gurugram and Greater Noida surpassed hundred (100) days of AQI levels above 200.
Seasonality plays a big part in the Air Quality Index
To analyse seasonal patterns in the Air Quality Index (AQI), we divided the year into two key periods: Category 1 (November to February) and Category 2 (March to June), with the remaining months generally covering the monsoon season. From 2015 to the present (24 October 2024), we tracked the number of days at each AQI level for these periods and calculated their proportions.
The data reveals a noticeable shift in AQI levels between the two periods. From March to June, most days fall within lower AQI categories, indicating better air quality, while the months from November to February show a concentration of days in higher AQI levels, signalling worse pollution. For example, in Delhi, only 5% of days between March and June were categorized as “Very Poor,” compared to 49% from November to February. A similar pattern was observed in Ghaziabad, with 10% of days rated as “Very Poor” during March-June, rising to 39% from November to February. This trend is consistent across many cities, highlighting the seasonal nature of air pollution.
Smaller Cities emerging as pollution hotspots
A closer look at city-level data reveals that smaller towns are increasingly emerging as pollution hotspots, challenging the dominance of traditional metropolitan areas. Towns like Begusarai, Varanasi, Hanumangarh, Ujjain, and Bhatinda are showing alarming trends in air quality. In 2023, Begusarai’s AQI stayed above 200 for eight months, a significant rise from three months in 2022. The city’s highest monthly average was recorded in January 2023, with an average AQI of 405. Similarly, Faridabad reported a monthly average AQI of 359 in November 2023.
In addition to these towns, several industrial hubs—such as Durgapur, Jodhpur, Bhiwadi, and Mandi Govindgarh—are also experiencing elevated AQI levels, signalling growing pollution concerns beyond the major cities.
