In California, diesel emissions bills sprout and multiply

The governor signs two bills, one accelerating clean truck technologies, the other creating a smog check program.

Still reeling from a new labor law that could reshape the way the trucking industry does business, carriers operating in California now have a pair of emissions regulations to contend with, one aiming to accelerate the transition to clean truck technologies, the other setting up a framework for a smog check program.

California Gov. Gavin Newsom signed both bills into law last week.

SB44, otherwise known as the “Ditching Dirty Diesel” bill by its sponsor, Sen. Nancy Skinner, requires the California Air Resources Board (CARB) to create a comprehensive strategy for medium- and heavy-duty vehicles that will allow the state to meet federal air quality standards and state greenhouse gas reduction goals.

“Tailpipe pollution from petroleum diesel is bad for our health,” Skinner said in a statement. “SB 44 will clean up our air and protect families and children.”


The trucking industry was less sanguine. “It sounds very alarming,” said Jimmy Nevarez, an owner-operator in Chino, California, referring to the potential costs tied to a clean truck transition. “Between AB5 and this, he’s [Gov. Gavin Newsom] just begging trucking companies to move out of state.”

AB5, signed into law last month, seeks to protect workers from employers that classify them as independent contractors instead of employees. It would be a disaster for the owner-operator business model, the industry claims.

From particulate matter to climate change

One of the new emissions laws, SB44, calls on CARB to develop a transition strategy for medium- and heavy-duty trucks by January 1, 2021, with a goal of meeting national air quality standards. Using $182 million from the Greenhouse Gas Reduction Fund, the law also directs the air pollution agency to set greenhouse gas emissions goals and identify incentives for fleets that limit pollution from their vehicles.


That directive expands on existing clean truck regulations, experts say. Because of longstanding diesel pollution mandates, big rigs in California are already much cleaner than they used to be, said Robert Harley, a civil engineering professor at UC Berkeley.  

“That takes some of the wind out of the sails around the ‘ditching dirty diesel’” tagline, said Harley, who has been measuring emissions from on-road, heavy-duty truck fleets since 2010. 

Nevertheless, SB 44 does contain important provisions, he said.

“It is going to give incremental improvements on NOx (oxides of nitrogen) and particulate matter that have already been addressed. The aspect of it that’s new is to switch away from petroleum-based fuels and address greenhouse gas emissions and climate change.”

Transitioning to diesel alternatives is a big ask, especially for long-haul trucking, Harley acknowledged, stating, “But we can’t just ignore the problem.” One important factor to consider going forward, he said, is to ensure the burden of transition doesn’t fall on owner-operators but to have shipping companies and other entities figure out solutions.

Initially adopted in 2008, California’s Truck and Bus rule, the state’s key regulation governing heavy-duty truck emissions, basically says that all heavy-duty vehicles will be required to have 2010 or newer model year engines by 2023. 

Smog check

The second bill signed into law last week, SB 210, requires heavy-duty trucks to undergo emissions inspection and maintenance testing, similar to the smog checks required for passenger vehicles. 


The law allows for the use of an onboard diagnostics data and test procedures to measure the effectiveness of the control of emissions of NOx and particulate matter. 

Compliance with California emissions regulations so far is about having the new or right model truck, Harley said. SB 210 builds on those regulations by requiring “functional tests” to ensure the emission controls systems are actually working.

Battle on all fronts

Vehicle emissions have dominated the California docket this past week.

On September 18, President Trump threatened to revoke a waiver allowing California to set its own emissions standards for passenger vehicles. The state promptly sued Trump to preserve that authority.  

Trump’s effort to revoke the waiver does not impact trucking emissions regulations. In the unlikely event his action is upheld in court, heavy-duty trucks will still have to meet the CARB standards.

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