Dozens of students, parents, teachers, and professionals joined a Friday protest organized by Extinction Rebellion that temporarily stalled morning rush-hour traffic in London’s southeasten borough of Lewisham to push politicians to more boldly address dangerous air pollution across the city.

The demonstration was just the first in a series of actions Extinction Rebellion (XR) is planning for the “Let Lewisham Breathe” campaign. Lorna Greenwood, who protested Friday despite being nine months pregnant, told the Guardian that “the idea was to stop traffic temporarily to put pressure on all of our politicians—Lewisham council, [London Mayor] Sadiq Khan, and the government—to confront the air pollution crisis.”

Though Khan has called the air quality issues that plague his city a “health crisis,” he criticized Friday’s action. A spokesman for Khan told ITV: “The mayor recognizes we face a climate emergency and shares the protesters’ passion for tackling this issue. But he is clear that causing disruption for Londoners in this way is unacceptable.”

Commuters were reportedly more supportive. Toting signs that declared “This Air Is Killing Us,” campaigners handed out leaflets and cake to drivers, and urged them to shut off their vehicles while they waited at the three locations of the sit-ins, according to organizers. They also warned of the disruption in advance, both online and with banners along the affected routes, and notified local schools and emergency services.

“There was some backlash but not as much as you would expect because people in the area know how bad the problem is,” Greenwood said. “Lewisham suffers really badly with air pollution so it’s at the forefront of everybody’s minds and it’s something that really unites people. It doesn’t matter what job you do or how old you are, people have to breathe the same air.”

“The environment catastrophe will far outweigh the damage caused by a few roadblocks on a Friday morning,” 35-year-old demonstrator Harry Gibson, who also participated in XR’s London demonstrations in April, told the Evening Standard.

“The planet’s not going to last, it’s not protected with the way that we’re going,” he warned. “We need to look to the future for future generations.”