New Delhi: India's polluted capital, New Delhi, will within two months impose a tax on commercial vehicles entering the city and prohibit the use of cars on certain busy routes once every month, its transport minister said on Tuesday.

High pollution levels have worried environmentalists, public and the authorities in the city of 16 million people, which the World Health Organization last year said had the worst air quality in the world. India rejected the report's findings.

Initiatives to clean up Delhi's air have hit roadblocks in the past. A directive this year to ban all vehicles older than 15 years has been delayed and previous city governments have often ignored court orders to address pollution woes.

‘Delhi's pollution levels are rising beyond dangerous levels,’ state Transport Minister Gopal Rai told Reuters in an interview. ‘If we don't address this, people will be forced to think about leaving the city to save their lives.’

Rai said his government will within two months impose a surcharge of up to 1,300 rupees ($20) on diesel-fuelled trucks that enter the city. For a longer-term solution, authorities are trying to build a peripheral road to divert traffic.

About 52,000 such vehicles enter the landlocked city each day, more than double government estimates, the Centre for Science and Environment (CSE) said in a report this week. Such vehicles account for about a third of the city's pollution.

India's top court on Monday gave Rai's government three days to devise a plan to address alarming levels of pollution caused specifically by commercial trucks. There have been several similar court orders in the last 15 years.

CSE's executive director, Anumita Roychowdhury, welcomed Rai's decision to levy a pollution tax, but said effective implementation was key.

‘Implementation has to be really effective to act as a deterrent. The track record to deal with truck pollution has been bad,’ Roychowdhury said.

Among other initiatives, starting Oct. 22, Delhi will enforce a car-free day on certain routes once a month. Rai has also urged citizens to adopt a one-car-one-family policy and increase use of bicycles.

The government is also evaluating a proposal to introduce staggered office hours to decongest traffic in the city, where jams run into several hours at peak travel time.

Pollution levels in Indian cities have often been compared to China's Beijing. The WHO study last year said Delhi had the worst air quality out of the 1,600 cities surveyed worldwide.

‘It (Delhi) is not the dirtiest city,’ Rai said, ‘but the problem is serious.’