Biden administration officials, including Vice President Kamala Harris, were set to announce roughly $1 billion in grants going to nearly 400 school districts to buy about 2,500 electric buses. According to a White House fact sheet, the money comes from the Bipartisan Infrastructure Law passed late last year.

“Youth development studies have shown that students need safe and healthy school environments to learn and thrive. This includes the way they get to school,” the White House said in the fact sheet. “Diesel exhaust from buses produces particulate matter and other pollutants that can cause lung damage and aggravate asthma and other health problems in children. In addition, diesel exhaust exposure has been linked to increased school absences.”

Only about 1% of the nation’s 480,000 school buses were electric as of last year, but the push to abandon traditional diesel buses has gained momentum in recent years. Despite this, Wednesday’s announcement is set to come as the United States is down to less than 30 days of diesel supply, with stockpiles at their lowest level for this time of year in records going back to 1993.

The $1 billion for electric school buses is also part of a wider Biden administration effort to accelerate the transition to zero-emission vehicles. Wednesday’s announcement comes on the same day the United Nations reported current pledges to cut greenhouse gas emissions put the planet on course to blow past the limit for global warming countries agreed to in the 2015 Paris climate agreement.

“Because of the damage already done to Earth and baked into the atmosphere, until we know how to remove emissions from the atmosphere and do something with them, even this past perilous year may well prove to be better than almost any year ahead of us unless we repair the planet at the pace that science demands and strengthen our adaptive capacity,” U.S. Climate Envoy John Kerry said earlier this week.

The Associated Press contributed to this report.