India monthly ambient air quality snapshot: April 2024

Authors: Manoj Kumar N and Sunil Dahiya

Key highlights

  • In April 2024, 215 out of 255 cities with more than 80% of the days with continuous ambient air quality monitoring station (CAAQMS) data recorded PM2.5 concentrations below India’s daily National Ambient Air Quality Standards (NAAQS) of 60 µg/m³. Only five complied with the World Health Organization’s daily safe guideline concentration of 15 µg/m³.
    • In April 2024, the monthly average PM2.5 levels in 95 (out of 98 cities with more than 80% days with data) National Clean Air Programme (NCAP) cities surpassed the WHO’s daily guideline for PM2.5, while 84 cities met India’s daily National Ambient Air Quality Standards (NAAQS).
    • Among the 157 non-NCAP cities with over 80% of days with CAAQMS data, two cities reported monthly average PM2.5 levels below the WHO daily guideline. 131 cities adhered to the daily NAAQS, while the air quality in the remaining 26 cities was poorer than the NAAQS.
  • April experienced a considerable improvement in air quality, with 65 cities falling under the ‘Good’ category, a stark contrast to March’s 43 cities. Despite this progress, there was a rise in the number of cities categorised as ‘Poor,’ increasing from one in March to six in April. March witnessed 163 cities classified as ‘Satisfactory’ and 49 as ‘Moderate,’ while April saw a slight decline to 150 and 33, respectively. Additionally, both months recorded one city each under the ‘Very Poor’ category. These shifts suggest varying degrees of air quality improvement or deterioration across regions during this period.
  • Byrnihat, an industrial town in Meghalaya, ranked as the most polluted city in India in April 2024, recording a monthly average PM2.5 concentration of 138 µg/m³, surpassing the daily NAAQS 83% days in the month. This is the third consecutive month the city has topped the list of most polluted cities. Among India’s top 10 polluted cities, three were located in Bihar, two in Haryana and West Bengal each, while Gujarat, Assam, and Odisha each had one.
  • Despite ranking as India’s 22nd most polluted city, Delhi’s pollution levels exceeded the NAAQS and were about five times the WHO daily guideline levels.
  • A total of 53 cities were featured in the daily most polluted cities list in April 2024. Of this, 23 made an appearance at least five times over the 30-day period, topped by Gurugram in Haryana featuring the most times (24 days) followed by Byrnihat (20 days), Muzaffarpur (18 days), Patna (16 days), Nayagarh (13 days), Faridabad (13 days), Ballabgarh (13 days), Asanol (12 days), and Chhapra (11 days).
  • The cities featured in the daily top 10 most polluted cities list in India were spread across 18 states and union territories (UT).
  • Only 17 out of the 53 cities featured in the daily top 10 most polluted cities list during April 2024 are part of the NCAP. The remaining 36  are devoid of any action plan to reduce hazardous air pollution concentrations.

Ambient air quality monitoring network

Only 101 of the 131 non-attainment cities under the National Clean Air Programme (NCAP) have a CAAQMS installed as of April 2024. The remaining 30 cities do not provide any transparent information on real-time pollution levels.

Durgapur in West Bengal received its second CAAQMS in April 2024, bringing the national tally to 541 CAAQMS across 281 cities.

Of the 281 cities with CAAQMS, 26 did not record data for more than 24 days (80%) in April, 12 of which did not record even for a single day.

NCAP cities

In April 2024, the monthly average PM2.5 levels in 95 NCAP cities surpassed the WHO’s daily guideline for PM2.5. Only 84 cities met India’s daily National Ambient Air Quality Standards (NAAQS) set by the Central Pollution Control Board (CPCB), with the remaining 14 cities recording PM2.5 concentrations exceeding the NAAQS; among these,  Byrnihat on the Meghalaya/Assam border recorded PM2.5 levels two times higher than the CPCB’s daily recommended standard of 60 µg/m³.

Non-NCAP cities

Among the 157 non-NCAP cities with over 80% of days with CAAQMS data in April 2024, only two cities (Puducherry and Palkalaiperur) reported monthly average PM2.5 levels below the WHO daily guideline.

131 cities adhered to the daily NAAQS, while the air quality in the remaining 26 cities was poorer than the NAAQS.


Air pollution levels and National Clean Air Programme (NCAP)

NCAP cities

In April 2024, only 42 out of the 98 NCAP cities complied with the daily NAAQS standard for PM2.5 on all days of the month.

Additionally, 78 out of the 98 NCAP cities consistently recorded PM2.5 levels exceeding the WHO-prescribed daily guideline levels every day of the month.

Non-NCAP cities

Among the 157 non-NCAP cities, only 66 cities experienced 100% compliance with the daily NAAQS for all days of the month. Also, 22 cities recorded PM2.5 levels, surpassing the daily NAAQS for 50% of the days in April.

Of the 157 non-NCAP cities, 121  consistently recorded PM2.5 levels above the prescribed daily WHO guideline on all days of the month.

In March 2024, 163 cities fell within the ‘Satisfactory’ category, with 49 cities in the ‘Moderate’ category. Additionally, there were 43 cities in the ‘Good’ category. There was one city each classified as ‘Poor’ and ‘Very Poor’.

However, in April 2024, there was a noticeable improvement in air quality, with 65 cities falling within the ‘Good’ category, indicating a significant increase from March. The number of cities in the ‘Satisfactory’ category slightly decreased to 150. The count of cities in the ‘Moderate’ category also decreased to 33, but there was a notable increase in the number of cities classified as ‘Poor’, with six cities. Also, only one city was under the ‘Very Poor’ category.


Ranking of the top 10 most polluted and cleanest cities in India

Byrnihat ranked as the most polluted city in India in April 2024, recording a monthly average PM2.5 concentration of 138 µg/m³, surpassing the daily NAAQS on 83% of days in the month. This is the third consecutive month the city has topped the list of most polluted cities.

Following Byrnihat, the other cities in the top 10 most polluted list for April were Gurugram, Muzaffarpur, Patna, Nandesari, Asanol, Faridabad, Chhapra, Nayagarh, and Durgapur, respectively, from the second to the tenth positions. Notably, six NCAP and four non-NCAP cities were included in this list, underscoring the widespread issue of hazardous air quality across cities beyond the current focus list of non-attainment cities under the National Clean Air Programme (NCAP).

Among India’s top 10 polluted cities, three were located in Bihar, two in Haryana and West Bengal each, while Gujarat, Assam, and Odisha each had one

Seven out of the top 10 most polluted cities recorded a higher PM2.5 concentration this April compared to April 2023.

There was a slight reduction of PM2.5 concentration in Byrnihat city compared to the same month last year. However, the concentration is still twice the Indian standards and nearly nine times the WHO daily guideline levels.

Muzaffarpur in Bihar and Nayagarh in Odisha had concentrations similar to those in the past year.

A total of 53 cities were featured in the daily most polluted cities list in April 2024. Of this, 23 made an appearance at least five times over the 30-day period, topped by Gurugram in Haryana featuring the most times (24 days) followed by Byrnihat (20 days), Muzaffarpur (18 days), Patna (16 days), Nayagarh (13 days), Faridabad (13 days), Ballabgarh (13 days), Asanol (12 days), and Chhapra (11 days).

The daily top 10 most polluted cities were spread across 18 states and union territories (UT), reiterating how widespread and severe toxic air is across the country. The 18 states and UTs are: Haryana, Assam, Bihar, Odisha, West Bengal, Gujarat, Punjab, Rajasthan, Uttar Pradesh, Madhya Pradesh, Tripura, Delhi, Chhattisgarh, Karnataka, Tamil Nadu, Maharashtra, Kerala, and  Telangana.

Only 17 out of the 53 cities featured in the daily top 10 most polluted cities list during April 2024 are part of the NCAP, while the remaining 36 cities still don’t have any action plan to reduce hazardous air pollution concentrations.

Surat in Gujarat emerged as the cleanest city in India in April 2024, recording a monthly average PM2.5 concentration that placed all 29 monitored days in the ‘good’ category (PM2.5 concentration lower than 30 µg/m³). Surat also recorded PM2.5 concentrations below the WHO daily guideline level of 15 µg/m³. Following closely behind were Varanasi and Bareilly in Uttar Pradesh, where questions on data quality once again made it to the news and cast doubt over recorded air quality improvements.

Additionally, other cities featured in the top 10 cleanest cities list for April 2024 included Puducherry, Palkalaiperur, Tirupur and Chennai in Tamil Nadu, Vijayapura in Karnataka,  Gangtok in Sikkim, and Barmer in Rajasthan.

Among the 36 states and union territories (UT) in India, only 29 had at least one city with a functioning CAAQMS providing data for more than 80% of the days in April 2024.

The remaining territories either lacked any installed CAAQMS, such as Andaman and Nicobar Islands, Dadra and Nagar Haveli and Daman and Diu, Goa, Ladakh, and Lakshadweep, or had inactive stations, as was the case in Srinagar.

In April 2024, 24 out of 36 state/UT capital cities had at least one CAAQMS installed, with data availability exceeding 80% of the days. However, the remaining 12 capitals lacked real-time data on air pollution levels.

Among the 24 capitals with monitoring systems, four cities exhibited air quality surpassing the daily NAAQS set by the Central Pollution Control Board (CPCB).

All capitals, except Puducherry, recorded monthly average PM2.5 concentrations exceeding the daily level recommended by the World Health Organization (WHO).


Air pollution across cities with million plus population in Indo-Gangatic Plains (IGP)

Out of 22 million plus cities across Indo-Gangetic Plain (IGP) states/UTs (Punjab, Chandigarh, Haryana, Delhi, Uttar Pradesh, Bihar, Jharkhand and West-Bengal), only 19 cities had an operational CAAQMS for more than 80% of the days in April 2024; others didn’t have CAAQMS installed, i.e., Saharanpur, Ranchi, and Jamshedpur.

Four out of 19 cities exceeded NAAQS, and these cities are located in Delhi, Bihar, West Bengal, and Haryana.

Notably, all cities in Uttar Pradesh had PM2.5 concentration levels below the NAAQS.


Air pollution across megacities in India- March 2024


Monthly ambient air quality trends in India: March 2024 air quality snapshot (pdf version)

Data sources

Ambient air quality data recorded by Continuous Ambient Air Quality Monitoring Stations (CAAQMS) is downloaded from the ‘Central Control Room for Air Quality Management – All India‘ dashboard operated by the Central Pollution Control Board (CPCB).


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