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Regulatory Rollback Could Stall Zero-Emission Bus Innovation

New resolutions may slow clean vehicle adoption, stalling momentum for zero-emission transportation and public health safeguards.

May 23, 2025
Regulatory Rollback Could Stall Zero-Emission Bus Innovation

According to the Environmental Defense Fund, this is the first time Congress has moved to undermine the state's Clean Air Act authority to do so, and it comes despite direction from the Senate parliamentarian that the Congressional Review Act procedure the Senate used was not allowable.

Photo: GILLIG/Cummins

2 min to read


This week, the United States Senate passed resolutions to overturn Environmental Protection Agency (EPA) waivers and overrule the Senate parliamentarian to revoke California's authority under the Clean Air Act.

This act, which allows California to set its own vehicle emissions standards, has been upheld by Republican and Democratic administrations for over 50 years. It has enabled the state to significantly reduce air pollution while spurring decades of innovation in the automotive industry, making today's zero-emission vehicles and buses possible.

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In the vote, the Senate overturned three regulations that would have pushed for more "clean" cars, trucks, and buses over the next 15 years. These waivers allowed California to implement the Advanced Clean Trucks (ACT), Advanced Clean Cars II (ACC II), and Heavy-Duty Omnibus (HDO) regulations.

According to the Environmental Defense Fund, this is the first time Congress has moved to undermine the state's Clean Air Act authority to do so, and it comes despite direction from the Senate parliamentarian that the Congressional Review Act procedure the Senate used was not allowable.

"This move concedes the industries of the future to global competitors, will increase air pollution, accelerate global warming, and result in significant job loss," John Boesel, Calstart president and CEO, said. "This vote upends decades of policy that has successfully resulted in cleaner air and the growth of a robust clean transportation industry."

House Joins Senate in Challenging EPA Safeguards

Additionally, the House of Representatives has passed Senate Joint Resolution 31, which would allow more cancer-causing hazardous air pollution from more than 1,800 industrial facilities and evasion from the EPA's longstanding clean air safeguards. The measure passed 216-212, with one Republican joining all Democrats in opposition.

If signed by the president, according to the Natural Resources Defense Council, this resolution would mark the first time Congress and the President overturned an EPA safeguard against hazardous air pollution, allowing industrial facilities to increase hazardous emissions.

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According to Calstart, dismantling these regulations may slow the acceleration of clean vehicle innovation, modernizing transportation fleets, expanding domestic supply chains, and growing clean manufacturing jobs nationwide. Plus, this change may undermine competitive momentum in U.S.-based clean transportation and electric bus manufacturing.

Without clear mandates or support for zero-emission bus adoption, delays in replacing diesel buses or missing out on incentives tied to regulations may become the norm again. However, curtailing California's ability to lead on emissions could create issues between state lines, where some could enforce stricter rules or propose inconsistent standards. 

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