The new speed cameras on the M4 near Port Talbot are now operational, the Welsh Government has confirmed.
After a permanent 50mph speed limit between junctions 41 and 42 of the M4 came into force on July 24 , additional cameras have now been installed.
The new cameras were due to be operational by the end of August , but it has only now been confirmed they are live.
In a statement, the Welsh Government said: " Tackling air quality is a priority for the Welsh Government and we are committed to building healthier communities and better environments.
"These cameras are aimed at reducing emissions and delivering vital improvements in air quality.”
Last year, a new report said junction 41 of the M4 for Port Talbot could be closed in a bid to cut pollution.
However, the idea was heavily criticised by politicians from the Port Talbot area, who feared a repeat of the “chaos” of four years ago when the junction was closed as part of a trial .
Businesses in the town also spoke out against the measure, claiming it would have a massive impact.
Then a report published later on in the year by the Welsh Government , exploring the different options to reduce pollution in the area, proposed to make the temporary 50mph speed limits permanent to achieve legal limits for NO2 within the shortest possible time.
In the report, it said: "The Welsh Ministers have taken the considered decision that the speed restrictions are the only measure that will achieve compliance with the NO2 limit values in this air quality zone as soon as possible, in a way that reduces exposure to NO2 as quickly as possible, and which mean it is likely, not just possible, that the limit values will be complied with."
The report found that junction 41 eastbound, or eastbound and westbound on slip road closures did not achieve as great a reduction in concentrations as the junction 41 westbound on slip only road closure would as a stand alone measure.
It said this could reduce pollution levels in the area, but the redistribution of traffic could result in increased exposure overall.
A trial slip road closure of this junction was carried out previously by the Welsh Government in 2015, it said in the report.
The slip road closure was not implemented at that time "due to the public feedback and other issues in the area, in particular the uncertain future of Port Talbot Steelworks", the report continued.
New cameras are also being installed on the A470 Upper Boat to Pontypridd , the A483 in Wrexham and the A494 at Deeside as the 50mph speed limits are enforced to improve air quality.
