 "Delhi AQI, air pollution, smog")
Delhi's air quality has improved slightly and now stands in the "poor" category. On Sunday morning, the national capital's air quality index (AQI) was 290, according to the Central Pollution Control Board (CPCB). This is due to favourable atmospheric conditions, primarily wind direction and speed.
On Friday, Delhi's AQI was close to falling into the "severe plus" category, following which the government would have implemented the odd-even car rationing measure.
The capital's 24-hour average AQI, recorded at 4 pm every day, was 319 on Saturday.
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The relatively better air quality last weekend is attributed to rain. Air pollution levels surged in the following days due to intense firecrackers 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 (276), Gurugram (322), Greater Noida (228), Noida (265), and Faridabad (309) also recorded poor to very poor air quality.
An AQI between zero and 50 is considered "good", 51 and 100 "satisfactory", 101 and 200 "moderate", 201 and 300 "poor", 301 and 400 "very poor", 401 and 450 "severe", and above 450 "severe-plus".
Grap measures lifted in Delhi
On Saturday, the Centre removed stringent curbs, including a ban on construction work related to linear projects and the entry of polluting trucks into Delhi, in view of the dip in air pollution levels.
These measures constitute the final stage, Stage IV, of the Centre's air pollution control plan called the Graded Response Action Plan (GRAP).
The Commission for Air Quality Management in National Capital Region and Adjoining Areas (CAQM), a statutory body responsible for formulating strategies to combat pollution in the region, asked Delhi and NCR states to revoke all emergency measures, under which only CNG, electric and BS VI-compliant vehicles from other states are allowed to enter Delhi, with exemptions granted to those involved in essential services.
All medium and heavy goods vehicles not engaged in essential services were also banned in the capital under Stage IV of GRAP, according to the latest CAQM order.
The pollution control body said all other curbs under stages I, II and III of GRAP, including a ban on non-essential construction work, mining, stone crushers and diesel generators, will continue.
The air quality forecasts by the India Meteorological Department/Indian Institute of Tropical Meteorology do not indicate any steep degradation in the overall air quality of Delhi-NCR in the coming days, the CAQM said.
Odd-even scheme in Delhi soon?
Earlier this week, Delhi environment minister Gopal Rai mentioned the possibility of the return of the odd-even car rationing measure if the AQI crosses the 450 mark. The measure, implemented four times since 2016, allows cars to operate on alternate days based on the odd or even last digit of their registration numbers. The last enforcement was in 2019.
Last week, the Delhi government postponed its implementation after a notable improvement in the city's air quality due to rain on Friday.
Recent findings from a joint project by the Delhi government and IIT-Kanpur found that vehicular emissions accounted for about 38 per cent of the capital's air pollution on Wednesday. This was reduced to 25 per cent on Thursday.
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 -- are the second major contributor to Delhi's foul air, accounting for 30 to 35 per cent of the air pollution in the city the last few days.
On Thursday, the Delhi government set up a six-member special task force to ensure strict implementation of measures outlined in the Grap in the capital. Delhi's special secretary (environment) will head the STF, whose members include senior officials from the departments of transport, traffic, revenue, Municipal Corporation of Delhi and Public Works Department.
Will air pollution in Delhi subside soon?
Calm winds and low temperatures are allowing accumulation of pollutants, and relief is unlikely over the next few days, an official at the India Meteorological Department (IMD) said. An improvement in the wind speed from November 21 onwards might bring air pollution levels down, he said.
Delhi's air quality dropped over the last few days despite the state government implementing stringent measures, including a ban on construction work and the entry of diesel-guzzling trucks into the city.
According to IQAir, a Swiss company that specialises in air quality monitoring, Delhi was the most polluted city in the world on Thursday, followed by Baghdad and Lahore. According to a report compiled by the Energy Policy Institute at the University of Chicago (EPIC) in August, air pollution is shortening lives by almost 12 years in Delhi.
An official of the Commission for Air Quality Management (CAQM) had earlier said stringent measures, including a ban on construction work and the entry of polluting trucks in the national capital, under the final stage of the central government's air pollution control plan called the Graded Response Action Plan (Grap) will continue until further orders.
(With agency inputs)
