Delhi’s air quality was poor or worse for 155 days in 2024

Layer of smog seen over Kartavya Path, Delhi.
| Photo Credit: Sushil Kumar Verma

The air quality in Delhi nosedived to hazardous levels on December 16, triggering the Central Air Quality Management (CAQM) in National Capital Region (NCR) and the adjoining areas to reimpose the Stage-IV restrictions under its Graded Response Action Plan (GRAP). When it comes to air quality at this time of the year, the story is no different since 2019, data from the Central Pollution Control Board (CPCB) shows.

Also read | Delhi air pollution: SC relaxes anti-pollution restrictions from GRAP IV to GRAP II in national capital region

In 2024 (until December 27), Delhi has witnessed 155 days of ‘poor’, ‘very poor’, or ‘severe’ air quality, that is, with an air quality index (AQI) of 200 or more. On the contrary, for the first time in six years, the city has not witnessed even one day of ‘good’ air quality days (AQI lesser than 50) in 2024.

However, over the last two years, there has been a slight improvement when it comes to the total number of days in a year where the air quality in the city was poor or worse. In 2022, the air quality in Delhi was poor or worse for 202 days or 55% of the year. This has come down to 159 days (or 44%) in 2023 and 155 days (43%) in 2024.

In 2020, when COVID-19 had triggered curbs and restrictions since March, Delhi had a total of 100 days where the air quality was ‘good’ or ‘satisfactory’, which means the AQI on those days was lesser than 100. It has only gotten worse since 2021.

The average quality of air has been ‘poor’ or ‘very poor’ in Delhi from October to February every year since 2019. The AQI in the month of November is the highest in the year, averaging to around 347 over the past six years.

This average dips a little to around 330 in the month of December, the air quality being, still, ‘very poor’.

During monsoon or July to September every year since 2019, the city has enjoyed an average AQI of under 120, barring July 2019 when the average was 134. This corresponds the the green patches in the heatmap above.

On December 25, the CAQM relaxed the GRAP curbs as the city witnessed a slight improvement in the AQI on December 24, when the AQI was 369, from December 23 when it was 429. An AQI of 400 points invokes the GRAP Stage IV curbs.