Lower speed limits in five poor air quality hotspots has reduced air pollution, says the Welsh government.
The 50mph limits were brought into force on sections of motorway and main road where air pollution exceeded legal EU limits.
A report looking into the first 12 months of the 50mph limits depicts a reduction in nitrogen dioxide at all five locations.
Transport minister Ken Skates, said: “I am encouraged by these findings in the first year of these speed limits, but it is vital we continue to reduce emissions in order to save people from the risk of developing potentially serious health conditions.”
Average speed cameras have been installed at four locations on the A494 at Deeside, A483 at Wrexham, M4 between junctions 41 and 42 at Port Talbot, and the A470 between Upper Boat and Pontypridd. In addition, the overhead cameras on the M4 smart motorway between junctions 25 and 26 near Newport are being used to enforce the new limits.
Camera warning signs fitted at the sites feature a green shield symbol instead of yellow, indicating the limits have been put in place for environmental reasons instead of safety.
Skates added: “I would hope most motorists would agree that helping to save people from illness or death is more important than saving a minute or so on their journey.”
A further report is due in March 2020 – this will see if the trend of reducing pollution continues until levels remain under the legal limit.