California is implementing a new regulation that requires public buses in the state to be 100 percent zero-emission by 2040.

On Friday, the California Air Resources Board (CARB) approved the Innovation Clean Transit regulation to reduce emissions from the transportation sector, which contributes 40 percent of climate-changing emissions and 80-90 percent of smog-forming pollutants.

California has 200 public transit agencies and their transition to zero-emission buses will help the state meet its air quality and climate goals. CARB estimated that the full implementation of its new regulation will reduce greenhouse gas emissions by 19 million metric tons from 2020 to 2050. It will also reduce around 7,000 tons of nitrogen oxides and 40 tons of particulate matter during the same period.

In a statement, CARB Chairwoman Mary D. Nicholas, said, “A zero-emission public bus fleet means cleaner air for all of us. It dramatically reduces tailpipe pollution from buses in low-income communities and provides multiple benefits especially for transit-dependent riders.”

“Putting more zero-emission buses on our roads will also reduce energy consumption and greenhouse gases, and provides cost savings for transit agencies in the long run.”

Some California public transit agencies already operating zero-emission buses

Currently, eight of the ten largest transit agencies already operate zero-emission buses including battery electric and hydrogen fuel cell vehicles.

Public transit agencies will gradually transition their bus fleets to zero-emission from 153 buses today to 1,000 by 2020. The goal is to ultimately shift about 12,000 buses statewide to zero-emission by 2040.

Under the regulation, each public transit agency must submit a rollout plan to bus zero-emission buses, build out necessary infrastructure, and train workers. Large transit agencies are required to submit their rollout plans in 2020 while small transit agencies in 2023.

According to CARB, public transit agencies will realize $1.5 billion savings in fuel, maintenance, and other costs by 2020 following the completion of infrastructure.