NEW DELHI: Delhi’s air quality improved overnight due to an increase in the wind speed and a change in the wind direction, but it still stands in the “very poor” category, according to monitoring agencies.
The city’s Air Quality Index (AQI) stood at 339 at 9 am, improving from 405 at 4 pm on Friday. The 24-hour average AQI, recorded at 4 pm every day, stood at 419 on Thursday.
The relatively better air quality last weekend was attributed to rain. Air pollution levels surged in the following days due to intense firecracker-bursting on Diwali night and a resurgence in stubble-burning in the neighbouring states.
These effects were compounded by unfavourable meteorological conditions, primarily calm winds and low temperatures, hindering the dispersion of pollutants.
Neighbouring Ghaziabad (274), Gurugram (346), Greater Noida (258), Noida (285) and Faridabad (328) also recorded “very poor” to “severe” air quality.
Recent findings from a joint project by the Delhi government and Indian Institute of Technology, Kanpur, found out that vehicular emissions accounted for about 45 per cent of the capital’s air pollution on Friday. This is likely to reduce to 38 per cent on Saturday.
Secondary inorganic aerosols particles such as sulfate and nitrate that are formed in the atmosphere due to the interaction of gases and particulate pollutants from sources like power plants, refineries and vehicles is the second major contributor to Delhi’s foul air, accounting for 19 to 36 per cent of the air pollution in the city over the last few days.