Delhi's first experiment with private vehicle restrictions ended yesterday after a 15-day trial that the government called a "success". It plans to thank Delhi residents, who largely followed the rules, with an event on Sunday.

"Lots of people talked about how great the system is in the US... Singapore and elsewhere... but 'odd-even' proved the same can be done here," said Delhi chief minister Arvind Kejriwal at a press conference yesterday. "Pollution did go down... (and) there was also less traffic congestion."

Still, experts said this was just a small step in the effort to clean up one of the world's most polluted capital cities. Yesterday, its air remained in the "unhealthy" category. With pollution levels up to 8 times above the safe limit on some days, the experiment hoped to tackle the problem by allowing only cars with odd-numbered plates to be used on odd days, cars with even-numbered plates on even days and shut schools for two weeks.

Experts said the biggest impact of the trial was an increase in awareness about curbing pollution. Mr Neeraj Dawra, 35, a marketing professional who used the metro and carpooled to get to work and back, said conversations at work and home centred around how pollution should be tackled.

"Nowadays, we keep on talking about pollution," he said. "How to decrease (it) and what measures should be adopted. I am scared about the effect of pollution on me and my family. But we can't do anything until the government takes effective measures. They need to improve public transport."

Pollution in Delhi has doubled over the last two decades with the increase in vehicles, burning of residue in nearby agricultural states and construction activity in the area. The Delhi High Court recently called the city a "gas chamber".

According to the System of Air Quality Weather Forecasting and Research (Safar), pollution levels remained "severe" in the first week of the experiment, but improved to the "unhealthy" range in the second week. Dr Gufran Beig, chief scientist at Safar, said they were still analysing the data, but weather conditions were mainly responsible for the decrease as winds dispersed pollutants faster.

Experts have urged the government to come up with a long-term strategy that combines emergency measures with more long-term solutions like congestion tax.

"Now that road rationing has been able to reduce traffic volume and free up road space, what we need is a solution to reduce traffic volume and reform public transport," said Ms Anumita Roychowdhury, executive director of the Centre for Science and Environment.

The government is looking at a series of measures, saying it will bring back the odd-even restrictions, but also encourage Delhi residents to cycle to work. It is holding a meeting on Monday to decide on the next set of actions.