Winter Yet To Set In, But Delhi's AQI More Than Doubles In 3 Days

A slight nip in the air signals the changing season, but winter is yet to arrive in Delhi. Yet, the national capital's air quality has deteriorated sharply over the past three days. Since Friday, Delhi's Air Quality Index (AQI) more than doubled as dry weather and slower winds allowed pollutants to accumulate. From 90 on Friday, the national capital's AQI rose to 159 on Saturday and 187 on Sunday, according to Central Pollution Control Board (CPCB) data.

Meanwhile, the temperature in Delhi and the national capital region (NCR) has fallen following the withdrawal of the monsoon. On Sunday, Delhi's temperature settled at 17.1 degrees Celsius, 1.3 degrees below the season's normal, the India Meteorological Department (IMD) said.

However, with no rainfall forecast over the coming week, air quality is expected to remain a concern.

Twenty two monitoring locations across the city recorded poor air quality on Sunday, indicating that pollution levels were already elevated in several areas. The worst air quality of 430 was recorded at ITO, placing it in the severe category.

On Saturday, Anand Vihar reported an AQI of 348, while Mundka recorded 227 and Jahangirpuri registered 212. Chandni Chowk recorded 188, while Vivek Vihar and Rohini both reported 187. Punjabi Bagh recorded 171, followed by Narela at 165, CRRI Mathura Road at 158 and Dwarka Sector 8 at 155.

On Monday, Delhi's AQI is expected to deteriorate to the poor category for the first time this season.

How Much Has AQI Risen Since October 1?

Delhi's AQI at Delhi's ITO station at 5 pm on October 1 was 132, according to CPCB data. In Jahangirpuri, the number stood at 216; for Punjabi Bagh, the same number was 178. In Anand Vihar, among Delhi's most polluted points, the 5 pm AQI on October 1 was surprisingly 96. This shows that in the 18 days of this month, the air quality has deteriorated significantly - that too, just before the winter season.

And the sharpest recent increase came after Friday's relatively clean-air reading.

The CPCB classifies AQI readings of 101-200 as moderate, 201-300 as poor, 301-400 as very poor and 401-500 as severe.

Why Is Delhi's Air Quality Worsening?

The immediate reasons include the absence of rain, slower wind speeds and emissions from local sources, including vehicles, road dust and construction activity. Rain and stronger winds can help disperse pollutants. As these conditions subside after the monsoon, emissions from everyday activities begin to accumulate closer to the ground.

The changing weather also plays a role. As winter approaches, cooler temperatures, lower mixing heights and stagnant winds can make it harder for pollutants to disperse.

What The Government Says

However, Delhi has recorded 211 days of good, satisfactory and moderate air quality so far this year, its best performance since 2016, except for the COVID-affected year 2020, Environment Minister Manjinder Singh Sirsa said on Saturday.

With more than two months remaining in the year, the national capital has already surpassed the total number of good-to-moderate air quality days recorded in most previous years, including 200 in 2025, 209 in 2024, 206 in 2023, 159 in 2018 and 110 in 2016.

The minister added that the number of days with poor, very poor and severe air quality had declined from 168 during the corresponding period in 2016 to 79 this year.