Plans are being considered to cut the speed limit on the Sheffield stretch of the M1 in a bid to cut pollution levels.
Drivers speeding over 60mph could be slapped with fines as Highways England plans to enforce the new limit between junction 32 and 35a.
The limit will come into force when the traffic levels on the 18 mile stretch from Aston to Chapeltown is at its busiest.
Highways England is considering imposing the restriction to try and address air quality concerns around the city and if the plans go ahead, the limit will run between 7am and 7pm, seven days a week.
The plan coincides with Department for Transport plans for a £106m 'smart motorway', which is due to launch in March.
The scheme is likely to add thousands of cars, vans and other vehicles to the roads, causing an increase in air pollution. Sheffield already misses EU air quality targets and was highlighted by the World Health Organisation for having dangerously high levels of air pollution.
Currently, around 120,000 vehicles per weekday use the motorway in Sheffield, according to Mouchel, an engineering consultancy that put together the report.
It estimates that the smart motorway scheme will add a further '5,000-10,000' vehicles a day by opening the hard shoulder to traffic.
The consultancy firm found that the best way to prevent an increase in illegal pollution would be to implement a speed limit.
Highways England said this was one of 'many options' being considered.
A Highways England spokesperson said: “Smart motorways are central to the modernisation of England’s motorways, reducing congestion and improving journey time reliability by smoothing traffic flows. One of our key challenges in delivering the £15bn government investment in infrastructure is tackling the issue presented by air quality and in order to meet environmental targets we are investing in wider programme of air quality research to help address this.”
A DfT spokesperson said: “We are firmly committed to improving the UK’s air quality and cutting harmful emissions. That is why we have invested more than £2bn since 2011 to promote greener vehicles and support green transport schemes and have set out how we will improve air quality through a new programme of clean air zones.”
The proposal comes as Sheffield’s Green party launch a campaign to tackle the city’s poor air quality. A statement said: “Air pollution continues to exceed legal limits in many areas, contributing to an estimated 500 premature deaths in Sheffield every year.
“We call on Sheffield city council to take action to tackle this public health crisis by urgently agreeing and implementing a new action plan to clean up the city’s air and protect our health.”