Proposed 'Stop CARB Act' Would End State-Set Emission Rules for Heavy Equipment, Revoke Existing Waivers

A new bill, the 'Stop California from Advancing Regulatory Burden Act of 2025' (or 'Stop CARB Act'), proposes a significant shift in how emissions are regulated for certain types of vehicles and engines across the country. If enacted, this legislation would amend the Clean Air Act to remove the long-standing ability of individual states to set their own emission standards—standards stricter than the federal baseline—for things like construction equipment, farm machinery, and locomotives (referred to as nonroad engines and vehicles). It also explicitly revokes any existing permissions, known as waivers, previously granted to states for this purpose under Section 209(b) of the Clean Air Act.

One Size Fits All Emissions?

At its core, this bill aims to create a single, uniform federal standard for these specific emissions, eliminating the patchwork of state-level regulations. Currently, the Clean Air Act allows states, most notably California, to apply for waivers from the EPA to implement tougher emission rules tailored to their specific air quality challenges. Other states can then choose to adopt California's stricter standards. Section 2 of the Stop CARB Act would repeal this waiver authority entirely for nonroad engines and vehicles, meaning states could no longer set rules exceeding federal minimums for equipment like bulldozers, tractors, or train engines. Furthermore, Section 3 repeals the provision allowing other states to adopt California's standards for new motor vehicles in general, centralizing standard-setting at the federal level.

What This Means on the Ground

The practical effect is straightforward: states lose the authority to enforce stricter-than-federal emission controls on these sources. For manufacturers, this could simplify compliance by creating one national rulebook instead of potentially multiple state-specific ones. However, for people living in areas with significant air pollution, particularly near industrial zones, construction sites, or rail yards, this could mean losing state-level tools designed to improve local air quality faster than federal standards might require. The bill essentially prioritizes national uniformity over state flexibility in addressing localized environmental or health concerns tied to these emissions. Revoking existing waivers (Sec 2) means states that currently operate under stricter rules would have to roll them back to the federal baseline.

States Lose the Driver's Seat

By eliminating the waiver process specifically mentioned in Section 209(b) and related sections of the Clean Air Act, this legislation takes away a key mechanism states have used for decades to address unique environmental conditions. It represents a fundamental change, moving control over these specific emission standards exclusively to the federal government. While proponents might argue this streamlines regulation, it undeniably restricts a state's ability to implement more aggressive environmental policies for these nonroad sources and prevents them from adopting California's established motor vehicle standards, potentially impacting long-term air quality planning and public health initiatives in various regions.