When big-rig trucks are required to get smog checks, California’s air will get better

In September the federal government determined that the San Joaquin Valley air district had attained a key milestone in its battle against pollution.

The U.S. Environmental Protection Agency said the Valley had reached attainment for a 24-hour standard of PM2.5 pollution. “PM” stands for particulate matter, the microscopic bits of air pollution that can get into a person’s bloodstream once inhaled. PM2.5 causes a multitude of health problems, including heart and respiratory disease.

But here’s the kicker: It took the district 24 years to achieve the mark. The standard was established in 1997.

Such is the difficulty of dealing with airborne pollution in the Valley, one of the two toughest air basins in the nation to clean up. The other one, of course, is Southern California’s South Coast basin. The Valley air basin runs from San Joaquin County on the north to Kern County at the southern end, and is framed by the Sierra Nevada and the coastal range, which is why it is so easy for pollution to get trapped in the region.

The biggest creators of PM2.5 pollution are semi trucks. While they represent just 3% of the vehicles on the road in California, diesel trucks generate 54% of all vehicular PM2.5 emissions in the state. And they spew more than half of all nitrogen oxides, a key component of smog.

In the Valley, big-rigs account for 40% of total ozone and nitrogen oxide emission, as well as the majority of particulate pollution for communities near major roadways.

Now the state air board is poised to launch a program that would require big-rig owners — from the operator with a single truck to giant fleets — to undergo regular smog checks. Up to now, diesel truck operators have faced periodic roadside checks, and single-truck owners have been exempt from annual inspections of their smoke output.

Getting compliance

The air board staff proposes that the emission equipment on big rigs be checked twice a year. Newer trucks have on-board diagnostic systems that gather performance data as the truck is operated. Owners of these rigs would be required to submit the data. Owners of older trucks without the built-in diagnostics would be directed to use certified technicians to reach semiannual compliance.

Of particular importance, the new rules would apply not just to California owners, but also operators from outside the state. The staff report notes that those vehicles cause 36% of the state’s PM2.5 pollution and 27% of its nitrogen oxides. If those out-of-state vehicles do not comply with the new regulations, then legally they could not drive in California.

The program would be phased in, starting Jan. 1, 2023 and reaching full scale a year later.

Critical health impacts

A consortium of health groups, such as the American Lung Association, back the proposal. “This is the most health-protective measure that CARB has considered in over a decade to advance California’s Clean Air Act responsibilities to protect public health,” the groups wrote in a letter to the air board.

Properly operating pollution-control equipment can yield major results. For example, air board staff noted that diesel particulate filters can trap 98% of PM2.5 emissions when a system is working as designed.

About 5,000 people in California die each year because of particle pollution — with half of those related to transportation sources.

The most pollution-burdened census tract in the state, as found in the most recent CalEnviro Screen, is just off Fresno’s downtown. People living there are adjacent to Highways 99 and 41, as well as a major freight train line. West Fresnans have long had acute asthma and heart disease, which are caused by dirty air, and as a result have much shorter lifespans than residents on Fresno’s cleaner northside.

The reaction from farming and trucking groups has been muted, with most comments focusing on technical details and not the overarching purpose of the program. Even those most affected get it.

Given the out-sized impact of diesel trucks, the California Air Resources Board should support the program and get it going immediately. This is one government mandate that everyone can back — especially in an era when e-commerce warehouses, which rely on big-rigs to ship their goods, are proliferating in the Valley.