Delhi’s grand plan to deal with record levels of pollution and clean its air appears to be stalling before it has even been put into action.

Arvind Kejriwal, the top elected official of the Indian capital, said last month that private cars would be allowed on the city’s roads only on alternate days from 1-15 January, with days allocated on the basis of whether licence plates ended in an even or odd number.

On Thursday, he announced a list of people exempted from that rule: all women, top politicians, judges, police and prison officials and sick people. He also left out two-wheel vehicles such as motorbikes and scooters.

He added an even bigger caveat: if the watered-down plan inconvenienced citizens the plan would be scrapped.

The effects of pollution in Delhi are palpable: grey, overladen skies, difficulty in breathing and the smell of vehicle exhaust.

Environmentalist Anumita Raichaudury warned that with so many exemptions the effectiveness of the government efforts would be compromised. “Two-wheelers should be brought within its mandate as they make a key contribution to pollution,” she said.

“We support the government effort, but it should be executed well.”

This week, the Indian capital was suffering from the worst pollution this season.

On Thursday, the Indian environment monitoring index showed record levels of PM2.5, particles with diameters no greater than 2.5 micrometres, which can be more damaging because they are small enough to be breathed deeply into the lungs.

The average PM2.5 levels for the capital on Thursday were over 293, almost five times higher than the Indian norm of 60 and almost 15 times the World Health Organisation (WHO) standard of 20.

Plans to clean up the city’s pollution had also included shutting down one of the oldest and least efficient power plants, a temporary ban on the sale of large diesel vehicles and a stiff toll for pollution-spewing trucks entering the Indian capital.

The supreme court earlier this month also banned trucks from entering the city if they were over 10 years old or just passing through. In addition, all taxis in the area, including private ride-hailing services such as Uber, have to switch to running on compressed natural gas by 31 March.

But it was the plan to reduce the number of cars on the sprawling capital’s roads that was the most dramatic.

Last year, the WHO named Delhi the world’s most polluted city, with 12 other Indian cities ranking among the worst 20. Air pollution contributes to more than 600,000 deaths each year in India.

The watering down of the plan has disappointed many who welcomed the announcement of Kejriwal’s grand scheme.

But for others even the watered-down scheme is better than nothing at all.

Economist Surjit Bhalla said the government had acted in response to pressure mounting from citizens who had become increasingly aware of the dangers. “But I am doubtful about its success.”