The exemption given to two-wheelers could be withdrawn after the first week of the implementation of the odd-even formula in Delhi, said AAP senior leader Adarsh Shastri.

Shastri on Monday said if enough buses were added on the roads, two-wheelers could also be removed from the present list of vehicles exempted from the new environment-friendly rule.

Two-wheelers account for 33% of particulate matter emissions, according to an IIT-Kanpur report.

"I don't see a problem in being able to embrace this plan. Yes, I agree two-wheelers should not have been exempted. But fact of the matter is today we don't have an alternate commute available for 50 lakh two-wheelers," he told NDTV.

Currently 2,700 buses — 300 less than the aimed number — have been registered in Delhi to work in accordance with the pollution-curbing formula.

As of now, the notification issued by the Delhi government says between 1 and 15 January, odd-numbered cars will ply on odd dates and even-numbered ones on even dates.

Single women, two-wheelers, VIPs like the Chief Justice of India, judges of the Supreme Court and the high court, Lokayukta, will be exempted from the rule. Also, people with medical ailments will be exempted, though the method to ascertain the nature of the ailment has not been specified, giving wiggle room to drivers who could feign sickness.

The rule is applicable between 8 am and 8 pm, and not on Sundays, and anyone found flouting the rule will be fined Rs 2,000. Cars from other states plying on Delhi's roads will also be subject to this rule.

Delhi Police Commissioner BS Bassi has criticised the formula, saying it was "rolled out in a hurry", while warning civilian volunteers from taking any action on their own. He said asking people to return or stopping them from travelling would be punishable under the IPC.

"The police can enforce the plan, not volunteers," he said, adding that it would be easier to roll out this plan without any exemptions, reported the Asian Age.

A rehearsal is expected to take place between 9 am and 11 am on 31 December by the coordination committee, composed of the Delhi Transport Department, Traffic Police, Divisional Commisoners (DC), District Magistrates (DM), Sub-Divisional Magistrates (SDM) and the Delhi Transport Corporation (DTC), reported ANI. 

There will no test run on 30 December, said Delhi Transport Minister Gopal Rai. 

The Delhi government has also tied up with Twitter to provide real-time traffic update for people. Tweeting with the hashtag #pollutionfreeDelhi and to @transportdelhi handle will elicit information about bus and metro routes.

Thousands of autos have also been registered, and metro rides are to be increased to 3,000, reports The New Indian Express.

The odd-even formula is being implemented in the world's most polluted city, New Delhi, to bring down the 2.5 particulate matter (PM2.5) level, which peaked after Diwali, leading to the formulation of this plan.