Delhi's AQI crosses 300 for first time this season, more smog expected in coming days

The Air Quality Index, or AQI, is a scale used to describe how polluted the air is. CPCB classifies 301-400 as “very poor” and 401-500 as “severe.” These categories signal a major deterioration from healthier conditions and matter because pollution is affecting the city broadly, not just one location.

Delhi’s AQI stood at 307 at 7.05 am on Monday. That placed the city in the very poor category. Jahangirpuri recorded 417, making it the only monitoring station in the severe category. The city’s 24-hour average AQI had been 261 on Sunday and 117 a day earlier.

The reading shows how quickly conditions changed after rain briefly cleared the air. The article reports that meteorologist Navdeep Dahiya expects unfavourable weather to worsen pollution over the next seven to 10 days. The coming Diwali period could also add pollutants through firecracker bursting.

Pollution had spread across much of Delhi by Monday morning. Data was available from 58 of the city’s 59 monitoring stations. Of those reporting stations, 36 recorded very poor air quality, showing that the deterioration was broad rather than limited to a single hotspot.

Jahangirpuri was the only station in the severe category, with an AQI of 417. Five stations remained in the moderate category, while all remaining stations were classified as poor. The distribution shows different pollution levels across the city, even as very poor readings dominated.

This widespread deterioration followed a sharp rise in Delhi’s overall AQI. The 24-hour average rose from 117 on Saturday to 261 on Sunday, while Monday’s reading reached 307 at 7.05 am. The spread of high readings supports warnings that Delhi-NCR’s smog could worsen in coming days.

PM2.5 and PM10 are particles suspended in the air, grouped by their size. PM2.5 consists of especially fine particles, while PM10 includes larger inhalable particles. The distinction matters because the article identifies which pollutant was driving readings at each monitoring station.

At 6 am on Monday, CPCB listed PM2.5 as the primary pollutant at 51 of 58 reporting stations. PM10 was primary at the remaining seven stations. A day earlier, PM2.5 led at 46 of 57 stations, while PM10 led at 11, showing a stronger dominance of PM2.5.

The article does not identify one single source for the PM2.5 recorded at each station. It links the broader pollution rise to persistent emissions, northwesterly winds, calm conditions, farm fires, and the approaching Diwali period. These conditions allow fine particles to remain in the atmosphere longer.

Rain can temporarily wash airborne pollution out of the atmosphere. In Delhi, heavy rain produced an AQI of 60 on Friday, giving the city its cleanest October day in four years. That improvement was short-lived, and pollution levels rose sharply afterward.

The change was visible in the readings. Delhi’s 24-hour average AQI climbed from 117 on Saturday to 261 on Sunday. By 7.05 am Monday, the AQI had reached 307. The article also reports calm conditions and northwesterly winds, which meteorologist Navdeep Dahiya said would allow emissions to persist for longer.

Other pollution sources were also active. NASA detected 1,394 farm fires in Punjab and Haryana between October 1 and November 1, including 171 on November 1. Diwali was one week away, when firecracker bursting typically adds to the Capital’s pollutant load. Together, these factors ended the temporary post-rain relief.

Very poor and severe AQI categories indicate heavily polluted air. In general, exposure can irritate the eyes, nose, throat, and lungs. It can also worsen asthma and other breathing or heart problems, especially for children, older adults, and people with existing conditions. These health effects are established air-pollution knowledge, not specific symptoms listed in the article.

Daily life may be affected because people can see thick haze, breathe less comfortably, and choose to reduce outdoor exercise or other prolonged outdoor activities. Schools, workplaces, transport, and public events may also face pressure to limit exposure when pollution is high, although the article does not report such measures here.

The article shows how serious conditions became. Delhi reached an AQI of 307, and Jahangirpuri reached 417. Meteorologist Navdeep Dahiya warned that smog would worsen across Delhi-NCR and the northern plains over the next seven to 10 days. The article does not provide medical advice or specific activity rules.

Pollution comes from multiple sources. Crop-residue fires release smoke and fine particles, while firecrackers add pollutants during Diwali. Traffic and industrial activity also emit particles and gases; these are established pollution sources, although this article does not quantify their individual contributions to Delhi’s readings.

The article reports 1,394 farm fires in Punjab and Haryana between October 1 and November 1. Punjab accounted for 1,249 and Haryana for 145, with 171 fires recorded on November 1. It also warns that firecracker bursting typically adds to the Capital’s pollutant load during Diwali. Burning residue, fireworks, vehicles, and industry can therefore add emissions to the same air mass.

Weather determines how long those emissions remain concentrated. Navdeep Dahiya reported northwesterly winds and calm conditions, saying emissions would persist longer. He expected no favourable meteorological conditions for seven to 10 days. The article does not provide separate traffic or industrial emission totals.

Wind helps move and dilute pollution. When conditions are calm, emissions from vehicles, fires, fireworks, and other sources are not dispersed as quickly. They can build up near the ground, where people breathe them. This is the basic atmospheric mechanism behind pollution accumulation; the article itself focuses on the calm conditions rather than explaining every winter process.

Delhi’s meteorologist Navdeep Dahiya reported northwesterly winds with calm conditions. He said emissions would persist in the atmosphere for a longer duration. As pollution accumulated, most AQI sensors across Delhi-NCR were reporting levels above 300, with some moving toward the 400-500 range.

The article describes the start of the smog season and warns that unfavourable weather will worsen pollution over the next seven to 10 days. It does not give a detailed scientific explanation of winter temperature layers or ground-level inversion. Its immediate message is that weak atmospheric movement can extend the life of pollution over Delhi and the northern plains.