Scotland’s first low-emission zone (LEZ) will be introduced in Glasgow on Monday, but campaigners have already said it will not achieve significant change.
The first phase of the LEZ will set emission standards which must be met by 20% of buses which pass through the city centre.
It means local bus services must comply with European emissions standards.
Phase two, applying to all vehicles entering the zone, is to be implemented in December 2022.
The scheme will be enforced through the use of Automatic Number Plate Recognition (ANPR) cameras.
But campaigners say the plan to phase out the dirtiest buses in the city centre over a five-year period will bring almost no change in the first year, and they have criticised the decision not to impose restrictions on all other vehicles until 2022.
Air pollution campaigner Gavin Thomson said: “The toxic, illegal levels of air pollution in Glasgow causes hundreds of premature deaths and life-limiting conditions.
“Unfortunately, the weak terms of this low-emission zone – only applying to one in five buses – won’t achieve any significant change for air quality.
“This ‘no ambition zone’ means fumes from transport in the centre of Glasgow will carry on poisoning people’s lungs for many more years.
“Around 18% of buses in Glasgow already met the emission standards before the zone was decided, so there will be very little change in the fleet.”
Councils in Edinburgh, Dundee and Aberdeen have discussed following Glasgow in bringing in LEZs.
Mr Thomson said councils must be bold in their approach to tackling pollution.
“Private bus operators in Glasgow are getting a free ride while everyone else is suffering the effects of illegal levels of air pollution,” he said.
“Three hundred premature deaths are caused by air pollution in Glasgow every year. We need bolder action by the council, and bus companies need to prioritise people over profits.
“We need our other city councils across Scotland to be bolder than Glasgow.
“With Edinburgh, Dundee and Aberdeen all planning their low-emission zones for 2020, there is an opportunity for cities to set a path to clean air, compel bus companies to clean up their fleet, and remove the worst polluting vehicles from city centres.
“Air pollution from transport is causing an urgent public health crisis and councils need to show leadership.”
A Glasgow City Council spokeswoman said the strategy will deliver a “manageable, yet robust” approach to reducing pollution.
“Glasgow is committed to cleaning up the air and is leading the way by introducing Scotland’s first low-emission zone at the end of the year,” she said.
“Glasgow’s LEZ is modelled as being capable of making significant reductions in levels of air pollution in the city centre. Focusing initially on local service buses, the strict emission standards required to enter the LEZ will apply to all vehicles by the end of 2022.
“This pragmatic and phased approach will ensure a manageable, yet robust timetable for implementation that looks at the city’s overall needs to ensure it won’t have a detrimental impact on people’s lives, businesses and the vitality of the city centre.
“Other cities across Europe adopted similar lead in times for their low-emission zones, so it’s seen as a reasonable amount of time to get the message out to businesses and residents so they are informed and can prepare.
“Glasgow’s LEZ is a progressive policy that will deliver cleaner air for the people of Glasgow.”