SACRAMENTO – A sweeping regulatory push by the California Air Resources Board (CARB) to decarbonise the state’s cold chain has reached a critical juncture, as aggressive enforcement of new transport refrigeration unit (TRU) standards collides with a mounting legal crisis. While fundamental requirements for refrigerants and particulate matter (PM) are now in active effect, the centerpiece of California’s climate strategy, a mandatory transition to zero-emission (ZE) technology, remains entangled in a complex web of federal litigation and administrative stasis.
The 2022 Mandates and the Enforcement Surge
The current friction stems from the 2022 Amendments to the TRU Airborne Toxic Control Measure (ATCM), designed to align the off-road sector with Executive Order N-79-20, which targets 100 percent zero-emission off-road equipment by 2035. These amendments represent a strategic shift from previous performance-based standards to a total technological overhaul.
Despite a lack of formal announcements, industry observers and legal experts report a significant crackdown on compliance. The Benesch law firm recently alerted clients that CARB is “ramping up enforcement,” particularly pressuring large warehouses and distribution centers to monitor the equipment using their facilities. Under the new rules, “applicable facilities” including refrigerated warehouses over 20,000 square feet and grocery stores over 15,000 square feet must register with CARB and either report all quarterly TRU activity or declare that only compliant units operate on-site. Failure to comply can result in staggering fines of up to $10,000 per day.
A “Dual-Track” Reality: What is Enforced?
As of early 2026, the regulatory landscape is divided. While the U.S. Environmental Protection Agency (EPA) granted a waiver for most of the 2022 Amendments, it notably declined to act on the zero-emission turnover requirements for truck TRUs. This has created a “dual-track” reality for fleet operators.
Currently, all TRUs operating in California, regardless of their home state, must meet the following active standards:
- Refrigerant Benchmarks: Since December 31, 2022, newly manufactured TRUs must use refrigerants with a Global Warming Potential (GWP) of 2,200 or less, such as R-452A.
- Particulate Matter (PM) Standards: Model Year 2023 and newer non-truck TRU engines must align with EPA Tier 4 final off-road standards, emitting no more than 0.02 grams per brake horsepower-hour.
- Administrative Compliance: Owners must register all units in the ARBER system, pay operating fees, and affix valid CARB compliance labels every three years.
The Zero-Emission Standoff
The mandate for fleets to turn over 15 percent of their truck TRUs to zero-emission technology annually is effectively in administrative suspension. In January 2025, the EPA’s partial waiver paused this requirement, informing operators they are not currently required to purchase ZE units until further notice.
This pause coincides with a broader “civil war” over environmental jurisdiction. In March 2026, the U.S. Department of Justice (DOJ) filed suit against CARB, arguing that ZEV mandates are preempted by the Energy Policy and Conservation Act (EPCA), which grants federal authorities exclusive power over fuel economy standards. Furthermore, the Clean Truck Partnership, a voluntary agreement between CARB and major manufacturers like Daimler and Volvo, collapsed in late 2025 after manufacturers sued to void the pact, alleging they were “strong-armed” into unconstitutional standards.
The Human and Economic Stakes
The push for cleaner technology is fueled by dire public health needs. CARB estimates that 40 percent of applicable facilities are located in disadvantaged communities, which bear a disproportionate burden of diesel exhaust and noise. The 2022 Amendments are projected to save $1.75 billion in statewide healthcare costs by 2034, preventing an estimated 177 premature deaths.
However, the industry warns of severe economic strain. The total net cost of the amendments is estimated at $850.2 million. Trade groups like the California Trucking Association (CTA) argue that ZEV technology is not yet viable for many routes due to battery weight, charging infrastructure deficits, and high upfront costs that can double or triple lease payments for small fleets.
Looking Ahead
While the ZEV transition for trucks is stalled, CARB is already developing “Part 2” of its rulemaking, which aims to transition trailer TRUs, railcars, and shipping containers to zero-emission technology by 2035. As the DOJ lawsuit proceeds, the future of California’s air quality goals hangs in the balance, forcing the global shipping industry to navigate a fragmented and litigious regulatory environment
