The Brief

Researchers at the University of Southern California have released an interactive map to show Angelenos how pollution from diesel truck traffic affects neighborhoods and streets across the region.

The map allows users to look at the number of diesel trucks that travel regularly though their communities, heading to or from the Ports of Los Angeles and Long Beach. It provides both ZIP code and street-level data.

Users can compare truck traffic in their neighborhood to other areas across L.A. County and track how it varies month to month. Most of the highest pollution areas are those closest to the ports.

“Diesel fuel can cause cancer in communities that are highly exposed to pollution, as well as higher rates of asthma, emergency department visits and heart disease,” said Jill Johnston of the USC Center for Children’s Environmental Health. “If you're near a busy freeway or roadway and you see trucks passing every day, that suggests really heightened risk for exposure.”

USC researchers say they hope the map can help L.A. residents make more informed decisions about their health.

Diesel exhaust accounts for more than two-thirds of cancer risk from air pollution in the Los Angeles basin, according to analysis by the South Coast Air Quality Management District — the region’s air quality regulator.

And despite some recent regulation and improved emissions standards for trucks going in and out of L.A.’s ports, 90% are powered by diesel fuel, according to the Port of Los Angeles.

Still, L.A. trucking professionals say their industry is getting cleaner — and argue that data collected by projects like USC’s don’t tell the full story.

“I think it's important to remember that these trucks have gotten significantly cleaner from where we started,” said Matt Schrap, CEO of the Harbor Trucking Association, a group that represents trucking companies serving West Coast ports.

Understanding your exposure risk

USC’s mapping tool breaks down truck traffic by both ZIP code and street, covering 15 months of data from January 2023 through March 2024. Users can:

• Check their ZIP code's ranking among 177 county zones for port truck traffic.
• View specific street-level data across 2,600 road segments.
• Track monthly variations in truck traffic.
• Identify if they live within three blocks of heavily trafficked routes.
• Compare their neighborhood's exposure to other areas across the county.

According to the map, the 10 ZIP codes with highest exposure are concentrated near the ports and along the 110, 710, and 605 freeways, which are trucking routes to rail yards and warehouses. Areas like Long Beach, San Pedro, and Wilmington are among those facing the greatest impact.

Diesel trucks from the ports, which transport 40% of all U.S. imports, generate harmful pollutants that pose serious health risks to residents living near the ports and along major trucking routes, according to environmental experts.

“This project was really driven by community concerns that have long-documented the ports of L.A. and Long Beach as major sources of truck traffic,” Johnston said. “It shows the disproportionate impact on low-income and communities of color.”

She said the map also reflects a concerning trend in recent years: diesel trucks traveling not just on freeways, but down residential streets. For example, in the Wilmington neighborhood, just north of the L.A. and Long Beach ports, one residential street recorded more than 17,000 trucks in a single week — approximately one every 38 seconds.

To generate the map, researchers used data from a sample of trucks equipped with GPS monitors. Environmental advocates say they hope tools like this can be used to push local officials to respond to specific community public health concerns.

“I think this report is helpful to understand who's most harmed,” said Adrian Martinez, deputy managing attorney at Earthjustice, and environmental advocacy group. “People living next to these large magnets for diesel pollution are breathing some of the most toxic air in the country.”

But trucking industry professionals argue that maps like this could be misleading, because different kinds of diesel trucks vary significantly as to how much pollution they disperse, and the data doesn’t account for exactly what type of vehicles are involved.

“There's no information on its drive train, its fuel type, its age, whether or not it's meeting a certain emission standard, whether or not it's utilizing renewable fuel,” Schrap said.

The USC Center for Children’s Environmental Health also tracked all truck traffic on one busy residential street, Drumm Avenue in the Wilmington neighborhood of Los Angeles. Using an infrared camera, it was possible to record every truck during a weeklong period in October 2023.

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USC Center for Children’s Environmental Health

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Why diesel is dangerous

Experts say diesel exhaust poses particularly severe health risks, including cancer, asthma, stroke and heart disease, especially for those living near high-traffic corridors.

Diesel engine exhaust is a complex mixture of thousands of gases and fine particles that contains more than 40 toxic air contaminants, according to the California Environmental Protection Agency’s Office of Environmental Health Hazard.

“These are really, really tiny dust-like particles that can not only enter into your lungs, but they can also enter into your bloodstream and into your brain and so these can have cardiovascular effects, respiratory effects, as well as impact cognitive functioning,” Johnston said.

The affects are especially concerning for vulnerable populations. Children face disproportionate risks, breathing in three times more air per pound of body weight than adults, Johnston said. Studies show pregnant women in these areas experience higher rates of infant death, low birth weight, and premature births.

Diesel fumes also contain other pollutants like nitrogen oxide, which contribute to urban smog. The Los Angeles area consistently ranks No. 1 in the country in ozone pollution in the American Lung Association’s annual State of the Air reports.

Will Barrett, the association’s national senior director for clean air advocacy, said smog can trigger a host of health emergencies and premature deaths.

In 2012, fumes from heavy duty cargo trucks caused an estimated 15,000 asthma attacks, 480 premature deaths and more than $5 billion in health-related costs in Southern California, according to researchers at UC Irvine.

Diesel particulate matter was responsible for 72% of the overall cancer risk from toxic air pollutants measured by the South Coast Air Quality Management District, which looked at a one-year period spanning 2018 and 2019. The agency also noted carcinogenic emissions have been gradually decreasing in recent years because of stricter regulations and cleaner technologies.

But they also stress that there’s more to be done.

California regulators recently abandoned a plan to phase out and eventually ban diesel trucks. But there are other ongoing state efforts that seek to provide incentives for the trucking industry to switch from diesel engines to electric and hydrogen-powered fleets.

On the federal level, the U.S. Environmental Protection Agency initiated a $3 billion Clean Ports Program aimed at transitioning to zero-emission operations and reducing pollution in port-adjacent neighborhoods. And on the local level, the cities of Los Angeles and Long Beach have launched clean truck programs to increase zero and low-emission vehicles in their fleets.

A chart recording all the entries and exits of trucks in the Port of Los Angeles by month from January 2023 to September 2024.

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USC Center for Children's Environmental Health

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Port of Los Angeles & Port of Long Beach

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Protecting your household

USC’s experts recommend L.A. residents concerned about diesel pollution start by reviewing the maps. If your home is within three blocks of a street with heavy truck traffic or if you live in high-traffic ZIP code, they recommend taking precautions, particularly if you have children or if you have a respiratory or heart disease.

For residents concerned about diesel exposure, USC recommends several protective measures:

• Install HEPA air filters indoors and maintain them regularly. (Learn more about them and see whether you qualify for an incentive program here.)
• Monitor daily air quality indexes and limit outdoor activities on high-pollution days.
• Regularly wet-clean and dust homes to remove settled pollutants, especially if there are young children at home who play on the ground.
• Maintain a diet high in antioxidants to help counter pollution effects.
• Choose exercise locations away from busy roads.
• If you regularly walk to work, school or public transit, rethink your routes to avoid busy streets.
• Reach out to local officials with concerns. (City councilmembers, county commissioners, air quality regulators, and members of the Board of Harbor Commissioners in Los Angeles and Long Beach.)

Need help making your own indoor air filter? USC has a guide:

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USC Environmental Health Centers

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USC Environmental Health Centers

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