Diesel big rigs have belched smog for years. California may soon ban them.

A layer of particulate matter is made visible over a residential area and commercial warehouses from the foothills of the Jurupa Mountains in Fontana, Calif. (Sofia Valiente/for The Washington Post)

BLOOMINGTON, Calif. — The two-acre plot was overgrown and unruly, but they could see the potential. Mountains crowned the horizon and the soil was healthy. There was room to roam — for their children and their animals. For Cecilia and Macedonio González, this patch of land 50 miles east of Los Angeles was a portal to their past and a promise to their future.

The couple picked the place some 15 years ago because it reminded them of where they grew up, in the Mexican state of Jalisco, and they wanted their children to feel connected to those roots. But these days, the family property doesn’t feel the same. Instead of the chorus of birds and roosters, it’s the growl of trucks. Hulking tractor-trailers that sport the names of some of the country’s largest corporations, such as Amazon and FedEx, or none at all.

Lines of them — sometimes lurching, sometimes buzzing, zipping past children walking home from school on the partially paved sidewalks of this mostly Latino unincorporated city and leaving a trail of noxious emissions.

“They’re invading us,” Cecilia González said, standing in her yard as the family’s goats bleated in the background. “For us, our American Dream was this: to have some land and for our children to get a formal education. We feel like we accomplished it, and now it feels like it’s being taken away.”

A vast warehouse — a truck magnet — now sits a few hundred feet away. As the expansion of the goods movement industry brought more warehouses and heavy-duty trucks to cities in this Southern California region known as the Inland Empire in recent years, grass-roots organizers and state regulators have worked furiously to clean up the sector, which they say is poisoning vulnerable communities, many of them populated largely with people of color.

In what may be one of the most consequential developments yet, the California Air Resources Board, a niche but powerful agency, appears likely to adopt a rule that would ban most diesel big rigs and other large vehicles that run on fossil fuels within the next two decades. For some, the transition would begin as soon as 2024. The move, which the board considered at a meeting last week, would drastically reshape the trucking industry and set a standard for the nation, just months after the state banned the sale of new gasoline-powered cars.

“There is no government that is today doing what California is doing” with the trucking rule, said Ray Minjares the heavy-duty-vehicles program director for the International Council on Clean Transportation, a research group. “It’s unprecedented globally.”

The effort to phase out big rigs highlights a long-standing paradox: California, famous for its hundreds of miles of beaches and the take-your-pick beauty of its iconic national parks, is also home to the country’s dirtiest air. Smog has choked parts of the state since the 1940s, and California cities regularly rank as the most polluted in the nation. The environmental movement here has made immense progress in the past half-century, but places near ports, along trucking routes and around warehouses are stifled by toxic emissions.

This reality has posed challenges for the nation’s wealthiest and most populous state, which has styled itself as an ambitious leader in the battle against climate change, setting lofty goals for the near future. Yet critics say the boldest rules are exercises in magical thinking. Advocates, meanwhile, insist the dire state of Earth’s warming atmosphere has left no room for moderation.

The trucking rule, dubbed the Advanced Clean Fleets regulation, is especially divisive.

A marathon air resources board meeting on Thursday encapsulated the difficulties that come with adopting such a sweeping proposal. The agency heard from more than 150 people, some demanding the rule be significantly strengthened, others complaining it was already unrealistic, noting that the state doesn’t have the charging infrastructure required for such a large number of electric vehicles.

“We see the potential for the technology, and our members are moving into it in the areas that make sense,” said Chris Shimoda, senior vice president of government affairs for the California Trucking Association, which represents the industry. “But the regulation is really just the moonshot, going for it all at once and much too quickly.”

Warehouse growth is booming, and the resulting environmental impacts are being felt disproportionately.

Across the country, discriminatory zoning practices and local ordinances have placed heavy polluting industry and bustling highways near low-income communities of color, isolating areas and creating unequal health impacts. Those patterns are profound up and down California, from the ports in Oakland and Long Beach to the freight routes in the Central Valley and the state’s south.

In the Inland Empire, a sprawling region east of Los Angeles that includes Riverside and San Bernardino counties, the spread of warehouses and the long lines of trucks they bring has exacerbated resident concerns. And the pandemic-fueled surge in online shopping has made the area even busier.

In the past seven years alone, warehouses have fanned out across the Inland Empire at a staggering pace. In 2015, they covered more than 590 million square feet in the two counties, according to a study by Pitzer College. By 2021, the number had ballooned to more than a billion square feet.

Once known for its abundant fields of citrus, the region has now been given the moniker “America’s shopping cart.” But public health experts have a different name for these high-traffic areas: diesel death zones — a reference to the chronic and sometimes fatal health impacts for those living nearby.

The big rig proposal remains relatively obscure outside of industry and activist circles, but it would have far-reaching consequences if adopted in or close to its current form. Transportation is responsible for 40 percent of California’s greenhouse gas emissions, and trucks are the dirtiest of the bunch. They account for 70 percent of smog-causing pollution and 80 percent of dangerous diesel particulate matter, despite making up just 6 percent of California’s registered vehicles, according to a state analysis.

The proposed regulation would require manufacturers by 2040 to sell only zero-emission medium- and heavy-duty vehicles. It would also set gradual milestones for certain operators to convert their fleets to electric, with state and local government vehicles leading the way, followed by drayage trucks, which transport shipping containers from ports and rail yards and are some of the road’s worst polluters. By 2035, all drayage trucks would need to be emissions-free.

Perhaps the most far-reaching categories of trucks targeted are those owned by the federal government and private fleets that the state considers “high priority,” defined as companies with at least $50 million in annual revenue or 50 vehicles, including the U.S. Postal Service, Amazon and FedEx. Those fleets would need to begin phasing in electric trucks as early as 2024 and gradually increase their share of zero-emission vehicles. By about 2040, most of these vehicles would be electric.

The rule would impact about 70 percent of California’s heavy-duty trucks, and the air resources board forecasts a head-spinning increase in the number of zero-emission trucks in the coming decades.

“This is probably the most substantial regulation to come out of California in a generation,” said Sean Cocca, the director of compliance at Gladstein, Neandross and Associates, a consulting firm that advises fleets on the transition to zero emissions. “This is akin to the conversion to catalytic converters back in the ’70s.”

The Thursday meeting was a crucial chance for the board to hear public comments that could shape revisions to the rule, which it will then vote on early next year. Members signaled their support for the proposal, which builds on a 2020 rule meant to encourage more zero-emission truck sales. But they also called for changes to the text and voiced concern about the state’s energy infrastructure, which has appeared particularly precarious during recent heat waves, with officials asking residents not to charge their vehicles during peak hours.

“We know we can achieve significant health benefits for communities if we move with all possible speed to remove diesel trucks from our roadways tomorrow,” said Liane Randolph, the board’s chair. “We also know this is going to be a transition with many challenges.”

New rules require a simple majority vote, though Randolph is expected to try to attain a broad consensus on the changes among fellow board members. Randolph and most of her colleagues expressed a willingness to enact the regulation in a somewhat revised form, citing the high stakes of phasing out diesel trucks and the road’s other big emitters.

The consequences have been playing out in neighborhoods for decades.

In the American Lung Association’s most recent assessment of polluted cities, California metro areas dominated the list of riskiest places. Riverside and San Bernardino counties scored failing grades across the report’s three measurements. Breathing air there comes with increased risk of cancer, heart and respiratory illness, and preterm birth.

“We live in some of the worst air pollution in the entire nation, we live and breathe that every single day, and that translates to a lot of our communities being really sick,” said Andrea Vidaurre, a senior policy analyst at the People’s Collective for Environmental Justice, a local advocacy organization. “If you live really close to these centers of pollution, it’s a reality you cannot escape — there’s a noise, a vibration, a smell you cannot escape, even if you go into your home.”

The air resources board, aiming to address health inequities, estimates the rule will save some 5,000 lives and lead to nearly $60 billion in health-care savings.

Many in the trucking industry also acknowledge the need for a transition to zero emissions — eventually.

But in the near term, drivers, fleet operators and industry lobbyists maintain that regulations like Advanced Clean Fleets are too radical and ignore concerns about the state’s energy grid and charging infrastructure. They also say it will further drive up costs for companies and consumers. Fleet operators who have asked local public utilities to supply power for large charging projects say they have been told it will take years to generate the capacity needed for that many megawatts.

“This infrastructure just does not exist today,” said Shimoda, with the California Trucking Association. “The utilities do not have a ton of spare power on their circuits.”

At its worst, Shimoda argued, the regulation could create “a major setback for trying to get zero emissions developed, because the experience of doing it is going to be so poor that you’re going to set back the cause.”

Since it released its draft proposal, the air resources board has said it would broaden the exemptions for fleets that cannot comply with the rule because of delays in infrastructure construction, responding to one of the industry’s major critiques.

Refueling his big rig at a Chevron station in south Fontana, a major logistics hub bordering Bloomington, Rigo Macias said he would welcome the death of diesel — after all, it just cost him $150 to fill a fraction of his tank. But buying a truck would put him out of business.

“Electric trucks — electric everything — it’s good for the atmosphere, it’s a good idea, but where’s the money?” said Macias, a 56-year-old who has been driving trucks for nearly half of his life. “We’re getting hurt every single day, real bad.”

Macias, who owns just one truck, would not be subject to the proposed regulation, but his anxiety about affordability speaks to larger concerns among drivers. The air board has been aggressively promoting the state’s subsidy programs, but some worry it won’t be enough.

Francisco Arellano lives just down the street from the Chevron, which is part of a cluster of gas stations and fast-food joints that cater to truckers. The neighborhood in south Fontana is one of the most polluted in the state.

The 28-year-old has spent his life in the city, and he has struggled with health problems for as long as he can remember, ones that he blames on the heavy truck traffic. One week in middle school, his nose bled so many times that this parents took him to the hospital to get the blood vessels cauterized, afraid he would choke in his sleep. Asthma and severe allergies have made everyday life difficult.

Driving through the city on a recent afternoon, Arellano pointed out warehouse after warehouse, some abutting schools and all attracting a string of semis. In nearby Rancho Cucamonga, where he works as a retail manager, there are far fewer signs of industry. The population is also much Whiter and wealthier on average.

“I can’t wait to leave Fontana,” Arellano said. “I would pay a million dollars to live in Rancho, where it’s just a few miles away and there’s no pollution.”

A couple miles northeast, Alondra Mateo lives near the intersection of a major truck thoroughfare and busy train tracks. The 22-year-old community organizer saw the impact of air pollution when traveling to San Bernardino for work, but when she relocated to Fontana a month ago, she didn’t know she was moving to an epicenter of the problem.

“Now I’m right in the middle of it — I have the warehouses, I have the train and all the big trucks that pass by,” said Mateo, who works with the People’s Collective for Environmental Justice.

In Bloomington, the González family and some neighbors have planted signs in their yards: The city is not for sale, they read. They are part of a small grass-roots group fighting to stop a warehouse project that would place another large facility in their backyard.

“Our small piece of open land here in Bloomington is being taken over by a sea of concrete all around us,” said Alejandra González, 34, one of Cecilia’s daughters.

She lives nearby and spends after-work evenings and weekend days at the house where she grew up, where she hopes her 3-year-old niece, Ximena, can have a similar childhood. But Alejandra is afraid of what might happen if another warehouse is built and more trucks begin to rumble past.

On a recent day, the two played at the far edge of their property, running around the way Alejandra did when she was a girl.

“Ximena, we’re going to get lost we’re so far over here,” she said.

“No, no, tía,” her niece replied. “We’re not going to get lost here; this is our home.”