Delhi pollution: Vehicles are the biggest reason behind AQI spike, says study

Vehicles, and not farm fire from Punjab, are the reason behind the recent spike in Delhi's air pollution as the Air Quality Index (AQI) continues to hover around the severe zone since Diwali last week. A study conducted jointly by the Delhi government and IIT-Kanpur found that carbon emissions from cars and two-wheelers have contributed around 38 per cent of pollution on Wednesday. The study has also predicted the share of vehicular pollution to hit 40 per cent today, November 16.

The national capital recorded a jump in pollution levels after burning of firecrackers on Sunday. According to the Central Pollution Control Board, Delhi’s PM 2.5 level touched a peak of 570 micrograms per cubic metre at 1 am, nearly 10 times the safe limit. Delhi had implemented stage four of GRAP earlier as pollution reached hazardous levels in the national capital for the past one week. The ban on BS3 petrol and BS4 diesel vehicles were extended beyond Delhi to neighbouring cities like Gurugram and Faridabad in Haryana, and Noida in Uttar Pradesh.

The study conducted by the Delhi government and IIT-Kanpur said that besides vehicular emissions, the second biggest reason for pollution are secondary inorganic aerosols like sulfate and nitrate. These particles are formed when gases interact with particulate pollutants from sources like refineries and vehicles. These pollutants contributed around 35 per cent to Delhi's foul air recently.

Gopal Rai, Environment Minister of Delhi, has already hinted that the government has not put the idea of reintroducing Odd-Even rule in the national capital in the back-burner yet. While plans to implement it earlier this week was postponed, the state government is keeping a close watch on the AQI metre and a decision on Odd-Even rule is expected by Friday. Rai said, "After 2-3 days, the wind speed may pick up. So it is expected that the situation will be better. We are now monitoring the situation. Tomorrow, we will sit with the scientists and the departments."

The Odd-Even rule puts restrictions on private vehicles plying on public roads. Vehicles with registration numbers ending in an odd digit are allowed to ply on alternate days and those with even numbers on the other alternate days. Critics, however, say that it has negligible impact on pollution levels and only serves to bring down congestion on roads.