California became the first state in the nation to regulate the transportation pollution produced by the surge in popularity of ridesharing on Thursday evening, as Gov. Jerry Brown signed SB 1014, a bill requiring transportation network companies (TNCs) to account for, and reduce, the greenhouse gas emissions of their operations.

The explosive growth of ride-hailing companies has left states facing a growing list of unintended consequences caused by on-demand transportation companies like Uber and Lyft.

SB 1014, sponsored by Assemblymember Nancy Skinner (D-Berkeley), requires state regulators to quantify emissions from ridesharing vehicles and set emission targets for TNCs, while requiring companies to develop plans to reduce those emissions. By prioritizing trips made in zero-emission vehicles, ridesharing companies can help popularize clean transportation, and help California meet its goal of putting 5 million zero-emission vehicles on the road by 2030.

Studies show that ride-hailing services have grown at the expense of public transit use and walking and biking. In San Francisco, it’s estimated that TNC companies produce the same amount of greenhouse gas emissions as 100,000 households produce in a year. That’s a big problem in California, where transportation emissions, the largest source of emissions in the state, have hit their highest level in ten years and are threatening the state’s ability to meet its climate goals.