Delhi recorded the most polluted December in 2023 in the last five years

However, the government data showed that overall, 2023 had the best air quality since 2018, barring 2020 when the pollution was low owing to the country-wide lockdown

Delhi recorded the worst December in 2023, in terms of air quality, in the last five years, according to the data released by the Ministry of Environment, Forest and Climate Change. Delhi's average air quality index (AQI) in the month was 348, the worst since 2018 when it was 360. In 2022, it was 319.

The ministry attributed the poor air quality to adverse climatic, meteorological, low temperature, and calm wind conditions in the region.

However, the data also showed that overall, 2023 had the best air quality since 2018, barring 2020 when the pollution was low owing to the country-wide lockdown imposed to control the spread of the Covid-19 pandemic. 

"As per the Central Pollution Control Board criteria for the air quality category based on gradation of the daily average AQI, the year 2023 witnessed the best ever 'Good to Moderate' AQI days, registering a mark of more than 200 days (barring Covid affected 2020)," it said.

An AQI between 0 and 50 is considered "good", 51 and 100 "satisfactory", 101 and 200 "moderate", 201 and 300 "poor", 301 and 400 "very poor", 401 and 450 "severe", and above 450 "severe-plus".

Notably, the number of days with "severe" and "severe plus" AQI was 15 during 2023, which was equal to such days in 2018.

"The year 2023 also witnessed much lower levels of episodic events like farm burnings during paddy harvesting season, bursting of crackers during religious festivals and marriages/celebrations, etc," the ministry added.

The data also highlighted that India saw the cleanest pre-Diwali and Diwali day in 2023 since at least 2018. The AQI on pre-Diwali and Diwali days was 220 and 218, respectively. In 2022, it was 259 and 312, respectively.

The announcement said that owing to the efforts of various stakeholders, the AQI of Delhi is likely to improve every year.

"With persistent field level efforts and targeted policy initiatives for quantified results in the short/ medium/ long term, it is expected that the air quality scenario over Delhi will see further gradual but marked improvement, year on year," it said.