Smog returns to Delhi: Is the capital bracing for another polluted winter?

Delhi’s overall AQI was 179 on Tuesday, placing the city in the ‘moderate’ category. The Air Quality Early Warning System forecast that air quality would worsen to ‘poor’ from Wednesday and remain there until October 23. This matters because pollution is building as winter approaches.

The change was already visible at individual stations. At midnight, AQI reached 273 in Bawana, 262 in Dwarka Sector 8, 248 at Delhi Technological University and 230 at the Dr Karni Singh Shooting Range. Readings from 201 to 300 are classified as poor.

The forecast also pointed to poor conditions during the following six days. Dussehra fireworks, farm fires, vehicles, construction dust, industries and waste burning all add emissions, while colder weather can slow their dispersal. Delhi’s Winter Action Plan is scheduled to begin on November 1.

Smog is a form of polluted haze. It contains airborne particles and gases from sources such as vehicles, fires, industries and construction. Ordinary fog is mainly made of tiny water droplets suspended near the ground. It can reduce visibility without necessarily containing high pollution levels.

In Delhi, the two can appear together. The article reported thick fog at Biodiversity Park near the CWG Apartments in Akshardham, while station readings showed poor air quality. That combination can make the air look especially dense and unpleasant. The key difference is composition: fog is a weather phenomenon, while smog includes pollution.

Delhi’s Wednesday haze came as temperatures fell and atmospheric conditions became less favourable for dispersion. The article does not identify the exact share of fog and pollution in the visible haze. It does establish that pollutants from several sources were accumulating during the seasonal shift toward winter.

The Air Quality Index, or AQI, converts measurements of air pollutants into a single number and category. It helps people and authorities quickly understand pollution severity. The article identifies 201 to 300 as the ‘poor’ range. It also reports that Delhi’s citywide AQI was 179 on Tuesday, classified as moderate.

Station-level figures showed why the citywide number could hide local hotspots. At midnight, Bawana recorded 273, Dwarka Sector 8 recorded 262, Delhi Technological University recorded 248 and the Dr Karni Singh Shooting Range recorded 230. Each reading fell within the poor range. AQI stations measure pollution locally, so values can differ across neighbourhoods.

The article does not list the pollutants or calculation formula used for Delhi’s AQI. In general, an AQI category signals increasing pollution and potential concern, but the precise health meaning depends on the pollutants and exposure. The forecast indicated poor conditions through October 23.

Delhi’s pollution comes from several sources, but the article gives no percentage breakdown for Dussehra fireworks, stubble burning, vehicles, construction or waste burning. Their individual contributions cannot therefore be ranked precisely from the available evidence. This matters because pollution control depends on identifying which sources are strongest at a particular time.

Dussehra fireworks can release particulate matter and other pollutants. The article also reports 19 farm-fire incidents across six monitored states: seven each in Punjab and Uttar Pradesh, four in Madhya Pradesh and one in Haryana. Vehicles, construction dust, industries and waste burning remain significant sources across Delhi.

The impact of farm fires depends on their number and location, wind direction and atmospheric conditions. The article says it is yet to be established how much Dussehra activity contributed to Wednesday’s smog. The most accurate conclusion is that multiple sources contributed, but their separate shares remain unknown.

When air remains in the poor category, people may face greater exposure to fine particles and other pollutants. Established health knowledge links polluted air with eye and throat irritation, coughing and breathing difficulty. Children, older adults and people with heart or lung conditions can be more vulnerable. The article itself does not report specific illnesses or hospital figures.

Daily life can also be affected by reduced visibility and haze. Delhi reported thick fog near the CWG Apartments in Akshardham, and several monitoring stations recorded poor air. High pollution may lead people to limit outdoor activity, although the article does not describe any such public response.

The forecast pointed to poor conditions through October 23, with a similar outlook for the following six days. Delhi is preparing controls on vehicles, construction, dust and industry. These steps matter because exposure can continue when multiple pollution sources combine with weather that traps emissions.

Authorities do not have to wait for weather to improve. They can reduce emissions at their sources by controlling traffic, construction dust, industry, waste burning and road dust. The article’s Winter Action Plan is designed for this purpose and will begin on November 1.

Specific measures include a No PUC, No Fuel policy, which denies fuel to vehicles without valid Pollution Under Control certificates. Non-BS-VI vehicles registered outside Delhi will face entry restrictions, subject to exemptions. The government also plans 50% work from home, construction restrictions, stricter dust monitoring and more mechanised road sweeping.

The Commission for Air Quality Management’s revised GRAP adds progressively stricter steps as pollution worsens. These measures target road dust, construction, polluting vehicles and other emissions. Their effectiveness will depend on implementation and enforcement. The article presents them as preparations for the seasonal pollution problem, not as proof that pollution has already been controlled.

Pollutants disperse when winds and atmospheric mixing carry them away or upward. In colder seasons, the air near the ground can become more stable, limiting that vertical mixing. A layer of relatively warmer air above can act like a lid, keeping emissions concentrated close to the surface. This is a general atmospheric mechanism.

Delhi’s Tuesday temperatures were below normal at key stations. Safdarjung recorded a maximum of 31.8 degrees Celsius and a minimum of 17.7 degrees Celsius. Palam recorded 29.3 and 17.3 degrees, while Lodhi Road recorded 31.4 and 17 degrees. The article links falling temperatures with conditions less favourable for pollutant dispersion.

As winter approaches, emissions from vehicles, construction, industries, fires and waste burning can therefore accumulate near ground level. Wind direction and other atmospheric conditions still matter. The AQEWS forecast expected poor air through October 23 and indicated poor conditions during the following six days.