By Alastair Lawson BBC correspondent in Dhaka

The government of Bangladesh has banned thousands of two-stroke three-wheelers, sometimes known as baby taxis, from the streets of Dhaka

They are sacrificing our daily livelihoods just because they want fresh air Golam Mustafa, ex-driver

The authorities argue that exhaust from the vehicles reduces air quality.

While environmental campaigners have welcomed the ban, it has not been well received by the drivers, or the city's hard-pressed commuters.

The vehicles have until now provided a cheap form of transport for many people who can not afford taxis.

Once the baby taxis are taken off the roads the price of travel in the city is expected to escalate.

Few alternatives

Three-wheeler drivers such as Golam Mustafa now face the prospects of unemployment.

'Baby taxis' provided a useful service

"I have little chance of finding a job elsewhere," he says, "they are sacrificing our daily livelihoods just because they want fresh air."

The ban has also not been welcomed by many of Dhaka's commuters who now face heftier travel bills because of the loss of at least 5,000 three-wheelers.

"Although it is a very good decision in terms of the environment, I think for people like me it will be quite expensive later on because I really can't afford taxis all the time," said one.

Another man pointed out the lack of public transport alternatives for Dhaka's working people.

Environmentally friendly

But environmentalists such as Salimul Haq say the ban will immeasurably improve air quality in one of the most polluted cities in the world.

"It is a good sign because the three-wheelers are the main cause of air pollution in Dhaka city," he says, "and the phasing out and replacement of them with cleaner vehicles is definitely going to make a difference."

But will it make transport more expensive?

Mr Haq is not sure the answer is clear. "The jury is still out on that one," he says, "they are being replaced with more and more vehicles powered by compressed natural gas (CNG).

"These are non-polluting, or at least less polluting, and not necessarily that much more expensive."

The ban on three-wheelers follows a similar ban on polythene.

The government of Bangladesh may have its critics but it has established a reputation as the most environmentally friendly administration in the country's history.