The burning of fossil fuels is a large contributor to climate change. It also contributes to outdoor air pollution, which health officials have linked to around 3 million deaths per year.
This move is just the latest in a series of efforts to battle pollution — Madrid and Paris have both temporarily restricted the number of cars on the road to fight air pollution before.
Now, the four cities are urging bus and car manufacturers to join that fight.
The mayor of Madrid said, "As we reduce the greenhouse gas emissions generated in our cities, our air will become cleaner, and our children, our grandparents and our neighbors will be healthier."
RELATED: Self driving cars of the very near future
Self-driving cars -- Google, Tesla
Self-driving cars -- Google, Tesla
Brazil's President Dilma Rousseff (L) takes a ride in a self-driving car at Google headquarters in Mountain View, California on Wednesday, July 01, 2015.AFP PHOTO/JOSH EDELSON (Photo credit should read Josh Edelson/AFP/Getty Images)
An Autopilot self-driving sign sits on the window of a Tesla Motors Inc. electric automobile store in Munich, Germany, on Monday, March 30, 2015. Chief Executive Officer Elon Musk wants to transform Tesla into more of a mass-market automaker by building a battery-cell factory big enough to supply 500,000 vehicles by 2020. Photographer: Krisztian Bocsi/Bloomberg via Getty Images
A Tesla Motors Inc. Model S electric automobile fitted with Robert Bosch GmbH automated driving technology drives on a test track in Boxberg, Germany, on Tuesday, May 19, 2015. The market for automated-driving systems might total $42 billion by 2025, Boston Consulting Group estimated in January. Photographer: Krisztian Bocsi/Bloomberg via Getty Images
A GPS driving sensor antennae sits on the back of a Tesla Motors Inc. Model S electric automobile at the Robert Bosch GmbH driverless technology press event in Boxberg, Germany, on Tuesday, May 19, 2015. The market for automated-driving systems might total $42 billion by 2025, Boston Consulting Group estimated in January. Photographer: Krisztian Bocsi/Bloomberg via Getty Images
MOUNTAIN VIEW, CA - FEBRUARY 02: U.S. Transportation Secretary Anthony Foxx inspects a Google self-driving car at the Google headquarters on February 2, 2015 in Mountain View, California. U.S. Transportation Secretary Anthony Foxx joined Google Chairman Eric Schmidt for a fireside chat where he unveiled Beyond Traffic, a new analysis from the U.S. Department of Transportation that anticipates the trends and choices facing our transportation system over the next three decades. (Photo by Justin Sullivan/Getty Images)
A camera peers out from the front grill of Google's self-driving car in Mountain View, California, on May 13, 2014. A white Lexus cruised along a road near the Google campus, braking for pedestrians and scooting over in its lane to give bicyclists ample space. AFP PHOTO/Glenn CHAPMAN (Photo credit should read GLENN CHAPMAN/AFP/Getty Images)
MOUNTAIN VIEW, CA - SEPTEMBER 25: People look at camera on top of a Google self-driving car at the Google headquarters on September 25, 2012 in Mountain View, California. California Gov. Jerry Brown signed State Senate Bill 1298 that allows driverless cars to operate on public roads for testing purposes. The bill also calls for the Department of Motor Vehicles to adopt regulations that govern licensing, bonding, testing and operation of the driverless vehicles before January 2015. (Photo by Justin Sullivan/Getty Images)