New lower speed limits at five spots in Wales has cut nitrogen dioxide gas pollution, the Welsh Government says.
The 50mph limits were introduced on trunk roads in Wrexham and Deeside, the M4 motorway at Port Talbot, the A470 towards Pontypridd, and a variable limit on the M4 at Newport.
The changes were brought in a year ago to help the Welsh Government hit EU and Welsh rules on air quality.
Transport Minister Ken Skates said he was “encouraged” by the latest results.
The speed limits have been under review as part of the monitoring of air quality in those areas affected, and will remain in place until nitrogen dioxide levels fall below legal limits.
“It is vital we continue to reduce emissions in order to save people from the risk of developing potentially serious health conditions,” said Mr Skates.
“I would hope most motorists would agree that helping to save people from illness or even death is more important than saving a minute or so on their journey.”
Average speed cameras were installed at four of the locations in August to enforce the 50mph limits, and became operational last month.
The Newport M4 stretch is already covered by spot cameras that match the variable limits imposed at peak times.
Environment Minister Lesley Griffiths added: “It is vital urgent reductions in nitrogen dioxide emissions are achieved to meet legislative requirements and to support our ambitions for a healthier and more globally responsible Wales.”
A further report focusing on air quality and pollution on the speed-restricted routes will be published in March 2020.