Extinction Rebellion protest blocks Sheffield ring road
Climate change campaigners caused major rush hour delays in a protest over road-widening.
Extinction Rebellion blocked Bridgehouses roundabout in Sheffield, with police liaison officers stepping in to calm irate commuters.
The group said Sheffield Council's £4.6m roadworks "undermine its declaration of a climate emergency".
The council wants Sheffield to be a "zero carbon economy" by 2030.
Sheffield Council declared a climate emergency after legal nitrogen dioxide limits were breached in the city since January 2010.
It has said air pollution contributes to 500 deaths in the city a year.
Extinction Rebellion said the A61 widening goes against the authority's plans.
"We applaud the improvements, but they must go further and faster, taking more radical action," the group said.
"Dimming street lamps and launching the Clean Air Zone consultation won't halt climate breakdown".
Cllr Mark Jones said the road widening meant short-term air improvements, allowing the "ambitious" zero carbon targets to be met.
But Extinction Rebellion said the roadworks "mock" the council's clean air intentions.
"Road-widening brings more vehicles into the city, condemning our children to more air pollution," the group said.
Waste-powered bin lorries are being trialled in Sheffield, with buses retrofitted for cleaner emissions.
But bus routes have also been changed or axed.