Junctions 33 and 34S on the M1.
From 28 September 2020 a lower speed limit of 60mph will be introduced at this location as part of a trial across the country to lower emissions through speed management. 
Based on their research they expect a reduction in NO2 when traffic speed is reduced from 70 to 60mph. The speed limits will be operational 24 hours a day and then assessed after 12 months to understand the impact on air quality levels.   
Drivers will see new signs on the network making clear that the speed limit is at 60 mph to improve air quality.