Faster motorway speeds in Kent 'will mean more pollution' say Greens

This is from Kent News:
Green campaigners have vowed to push for reduced motorway speed limits despite transport chiefs in Parliament considering a possible rise by the summer.
MPs could be asked to vote as soon as July on plans to raise the limit from 70 to 80mph as part of a new road safety strategy, due to be considered in May.
Kent Green Party has also repeated calls for 20mph limits in residential areas, prompted by a rise in the number of child casualties on the roads.
Chairman Stuart Jeffrey said: "This problem has gone on far too long. It’s time for action. Kent needs an immediate change to 20mph limits in all residential areas. As we know, residents overwhelmingly support this, the last government supported this and public health experts support this.
"There is no excuse not to implement it."