The national capital's air quality was recorded in the "poor" category on Sunday morning, while a government agency said it is likely to improve slightly in the coming days due to a change in the wind direction.
The city recorded an overall air quality index (AQI) of 218 at 10:30 am, with Jahangirpuri (AQI 283) recording the highest pollution levels in the capital.
On Saturday, the 24-hour average AQI stood at 221, which falls in the "poor" category.
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'', and 401 and 500 ''severe''.
The Ministry of Earth Sciences' air quality monitor, SAFAR, said the AQI is likely to improve to the "moderate" category by Monday.
Farm fires were observed in Punjab adjoining Pakistan, Haryana, and Uttar Pradesh which is likely to impact Delhi's air quality on Sunday, SAFAR said.
However, the wind direction will change to easterly and the impact of farm fires will reduce, it said.
On Sunday morning, Delhi's minimum temperature settled at 19.8 degrees Celsius. The maximum wind speed was 15 kilometers per hour and the direction was west-northwesterly.
Low temperatures and stagnant winds help in the accumulation of pollutants near the ground, affecting air quality.
High levels of air pollution in Delhi is a year-round problem, which can be attributed to unfavourable meteorological conditions, farm fires in neighbouring regions and local sources of pollution.
According to an analysis by the Council on Energy, Environment and Water, a Delhi-based think tank, transportation contributes the most -- 18 to 39 percent -- to Delhi's air pollution.
Road dust is the second-largest source of air pollution in the city (18 to 38 percent), followed by industries (2 to 29 percent), thermal power plants (3 to 11 percent) and construction (8 percent).