Delhi Chief Minister Arvind Kejriwal on Thursday launched a government campaign and urged citizens to switch off the engines of their vehicles while waiting at traffic signals as the air quality in the Capital deteriorated sharply. Kejriwal said the “Red light on, gaadi (car) off” initiative could lead to significant reductions in pollution levels.

The overall air quality index or AQI was 326 at 3.30 pm in Delhi on Thursday, according to government-run monitoring agency System of Air Quality and Weather Forecasting and Research. This indicates “very poor” conditions that pose a risk of respiratory problems.

At a press conference, Kejriwal said experts have told him that even if 10 lakh vehicles out of the 1 crore ones in the city join the campaign, the PM10 levels would fall by 1.5 tonnes and the PM2.5 by 0.4 tonnes in a year. PM2.5, particles that are less than 2.5 microns in diameter, can be carried deep into the lungs, causing diseases like cancer and cardiac problems.

“When the vehicles are idling [waiting at a traffic signal with the engine on], a huge amount of smoke is produced,” Kejriwal said. “And now think – there are 1 crore registered vehicles in Delhi. Imagine how much pollution is produced when even 30-40 lakh vehicles stand at traffic signals when kept turned on.”

Experts say more is fuel is wasted when vehicles are idling at traffic signals than when moving, the chief minister added. “On average, a vehicle spends 15-20 minutes at a traffic signal,” he said. “In these 15-20 minutes, a vehicle consumes about 200 ml of fuel.”

Kejriwal said that turning off vehicles at traffic signals could lead to savings of around 200 ml of fuel per day, amounting to a possible reduction of Rs 7,000 on fuel expenses per year per vehicle.

The chief minister also pointed out that stubble burning contributes to the pollution in Delhi. The Ministry of Earth Sciences’ Air Quality Early Warning System for Delhi, however, said the impact of stubble burning on the Capital’s air quality is marginal. Union Environment Minister Prakash Javadekar has also ruled out the farm fires as a major reason behind Delhi’s air pollution problems.

“We cannot do anything about the smoke coming to Delhi from stubble burning but we can take all steps we can to curb the pollution in the Capital,” Kejriwal said at the digital briefing.

The chief minister said the government has taken various steps to reduce air pollution, including an anti-dust campaign, use of bio-decomposer to avoid stubble burning, electric vehicle policy, tree plantation policy, among others.

The Delhi government had on Wednesday issued directions to its officials to implement measures under the Graded Response Action Plan. These include increasing metro and bus services, hiking parking fees and stopping the use of diesel generator sets. The plan is a set of anti-pollution measures Delhi and the nearby towns follow when the air quality deteriorates.

Kejriwal appealed to the citizens to adhere to the government campaign, especially during the winters when the air quality typically worsens. It was in the “poor category” for six consecutive days after it began to decline on October 7 for the first time in over three months. It deteriorated to the “very poor” category for the first time this season on Tuesday.