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Climate and Environment

Heavy Duty Diesel Trucks Will Now Be Required To Get Smog Checks

The 10 freeway in California at dusk, as heavy duty trucks and cars travel on both sides, their headlights and backlights glowing in the twilight
Diesel trucks and cars travel the 10 freeway near Banning in Riverside County
(David McNew
Getty Images)
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For most of us, getting a smog check on our car is a regular, if somewhat annoying, occurrence. But California’s most polluting vehicles, heavy duty diesel trucks, haven’t had the same level of oversight.

That changed on Thursday, when the California Air Resources Board, the state agency that forms policy around air pollution and climate change, voted to enact a smog check program for the approximately one million heavy-duty diesel trucks operating in the state. The program will go into effect in 2023.

The new program rolls out legislation by Senator Connie Leyva that Gov. Gavin Newsom signed into law in 2019.

Although big rigs and other heavy-duty vehicles make up only 3% of traffic on California highways, they cough up more than half of the pollutants that give L.A. its notorious smog, according to the Air Resources Board.

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Diesel exhaust is dangerous. Exposure to it increases the risk of asthma, cancer and other health problems. People of color, who disproportionately live in neighborhoods near freeways, ports, warehouses and industrial areas, have borne the brunt of these health impacts for decades.

Outsize Impacts

Regulators say lowering emissions from this relatively small group of polluters will have outsize impacts for public health.

They estimate that through 2050, the new policy will help prevent more than 7,500 premature deaths and thousands of emergency room visits for illnesses like asthma and heart disease.

Currently, heavy-duty vehicle inspection programs rely on random field inspections by the agency’s staff as well as yearly self-reported inspections for fleets of two or more heavy-duty diesel vehicles.

The stricter regulations include twice-a-year inspections and the use of remote monitoring devices to identify high emission vehicles. The new program will also include independent owner/operators who were previously exempt from periodic inspections.

Regulators have found that most of the state’s truck pollution comes from 11% to 17% of heavy-duty vehicles.

The initial focus will be on the San Joaquin Valley and South Coast region, both of which have some of the worst air quality in the California.

Years Of Pressure — And Years Of Resistance

The policy is not only a way to clean up our air, it’s also a strategy to help slow the climate crisis. In California, the transportation sector remains the largest contributor of emissions that are heating our planet. Heavy-duty trucks are responsible for a large chunk of these emissions.

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The decision comes after years of resistance from the trucking industry, and pressure from environmental advocates and the communities most impacted by dirty air.

The policy is another tool in the state’s growing arsenal of policies that aim to combat the climate crisis and improve air quality by lowering emissions from cars and trucks. Last June, the Air Resources Board passed a rule that requires all trucks sold in the state be zero-emission by 2045, the first policy of its kind in the United States.

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