Plans for a once-a-month car-free day to curb pollution in Southampton have been proposed.
The scheme could see streets in the city centre closed to traffic on Sundays.
Clean Air Southampton and Southampton Friends of the Earth has put the proposal to the city council.
It is understood it is currently being considered by authority bosses, the Local Democracy Reporting Service (LDRS) said.
The campaign groups are asking the council to start the initiative in September.
Clean air zone
Last May, the city was named by the World Health Organization as being at the limit for levels of fine-particle pollution.
To help improve air quality in the city a non-charging clean air zone is being introduced.
Under the plans taxis and buses will have to meet low-emission regulations.
Last month, funding of £1.8m was secured from the government to help fund the plans.
Southampton is one of four English cities preparing to introduce clean air zones by next year - the others are Birmingham, Derby and Leeds.