Port area pours out a toxic diesel cocktail

AQMD report measures some of L.A.’s sins of emissions, but doesn’t go far enough

By Tom Politeo
April 2001

A toxic air blanket extends from the San Pedro Channel to downtown Los Angeles and follows shipping lines all over Southern California. Diesel fumes are responsible for most of the cancer risk caused by bad air.

This AQMD map shows cancer risk from all emission sources, with diesel exhaust responsible for about 70% of the risk. Darker areas correspond to higher risk. The lightest, lowest-risk areas have less than 200 cancer cases per million people, while the black areas—including the port—have more than 1,200 cases per million risk.

Wilmington and San Pedro may have the most unhealthy air in the greater Los Angeles area, according to a government report. By a small margin, Wilmington edged out other locations in the dubious competition to have the worst air in L.A. A Southern California Air Quality Management District report published last year shows a general improvement in air quality from all toxic pollutants, except one: diesel exhaust. The cancer-causing fumes follow the ships, trucks and trains of the shipping industry all over the Los Angeles Basin, with the highest concentrations near shipping centers and along freeways. The air is worst near the harbor, along the 110 and 710 freeways in downtown Los Angeles and near the airport.

Southern California residents breathe a cocktail of toxic fumes, including hexavalent chromium, lead, benzene, perchloroethylene (from dry cleaning), carbon tetrachloride and numerous other compounds. Clean air regulations have brought the the cancer risk associated with these compounds (excluding diesel) from about 450 cancer cases per million people, down to about 150 per million in the past decade.

However, the AQMD study doesn’t give any annual figures to compare the risk from diesel fumes. Because there has been little regulation of diesel emissions and a significant increase in shipping (trucks, trains and ships), it’s likely that the risk associated with diesel use is on the rise.

With plans in the works that will dramatically increase shipping through the Port of Los Angeles (in San Pedro and Wilmington), it is likely that the risk associated with diesel exhaust will rise still further unless something is done to mitigate the pollution.
Diesel fumes are already responsible for almost four times as much cancer risk as all other chemical compounds combined, though research is still being done as to exactly how much risk diesel is responsible for.

In the worst case, diesel fumes may be responsible for 25 times the risk from all other sources. This would raise the risk of getting cancer from about one person in 750 people to more than one person per every 100. In the best scenario, diesel fumes may be responsible for twice the cancer risk of all other sources combined.

The Los Angeles Harbor Department is projecting shipping to increase through the harbor two to three times over current levels in about the next 10 years. If there is no improvement in shipping technology, the increased ship, truck and train traffic will increase diesel pollution and our health risks accordingly.

Fortunately, there are some plans to clean up American-operated diesel trucks. Though the improvement is welcome, it will kick in too late to help clean up our air in the short term and it will not reduce cancer risks to acceptable levels alone, especially with increased shipping.

Further, plans to clean up American trucks will not improve emissions from trucks that come in to the U.S. from Mexico, and the U.S. may not be able to regulate those trucks under international trade agreements. Further, the large cargo vessels that berth in the harbor contribute a substantial percent of our diesel pollution, and local government may not be able to regulate those either, because of international trade agreements.

One of the underlying problems with air pollution in the Los Angeles Basin is that much of it follows socioeconomic lines, with poorer neighborhoods closer to industrial pollution sources. In San Pedro, for example, neighborhoods closest to the port have the worst air. Neighborhoods further west and up San Pedro hill have progressively cleaner air and higher price values.
However, people living in upscale neighborhoods can’t necessarily breathe much easier. Air throughout the L.A. Basin has generally poor quality, and there are numerous counter examples where higher income neighborhoods have terrible air. San Pedro itself offers such examples.

As part of its environmental justice initiative, the new AQMD study added three sites to its list of air monitoring locations: Wilmington, Compton and Huntington Park. The new study is called MATES-II, or the AQMD’s second Multiple Air Toxics Exposure Study (a follow-up to the 1990 MATES-I). As a result, the new study monitored 10 total fixed sites.

The MATES-II study consists of two major sections. The first involves monitoring (or measuring) air quality at each of the 10 sites plus a number of “micro-scale” sites. The second involves a three-dimensional computer model of air pollution in the L.A. Basin.

It is the computer model that shows Wilmington has the highest cancer risk among the 10 monitoring sites in the basin.

Unfortunately, the AQMD monitored diesel pollution at only eight of the 10 monitoring sites and Wilmington was not among them. That leaves a potentially confusing hole in the study.

Further, the study doesn’t explain why diesel emissions weren’t monitored in Wilmington—or in Compton, the other site where there was no diesel monitoring. Though the modeled data corresponds to the measured data fairly well, there are some differences in ranking as to which site has the most unhealthy air. Overall, the measured and modeled data are within 20 percent of each other, which would seem to be a good sign that the model is fairly accurate.

It’s fairly surprising that the study didn’t monitor diesel emissions in the harbor area since another map in the study shows that the harbor is the area that creates the most diesel pollution.

Though the study might suggest that longshore workers may be at particular risk, it doesn’t provide sufficient data to evaluate the depth of that risk. The study doesn’t present enough detail to show whether risks are higher dockside than inland. Also, though the study shows seasonal variation in risk—with May being the safest month and November to January being five times more dangerous—it doesn’t show how much the risk factor may vary by time of day. Understanding daily cycles might also be helpful in determining exposure levels for longshore workers.

Lastly, though the study appears to show that the harbor is the basin’s largest source of diesel pollution, and though it provides a detailed breakdown of pollution by various categories, it doesn’t show how much of the region’s diesel pollution is caused by port activity.

For years, the Port of Los Angeles has broken down its EIRs into small projects and has only listed the component of air pollution generated within the confines of those projects. This policy has left the public without a clear understanding of the comprehensive risk created by the port. The MATES-II study is an important first step in demonstrating that risk.

But the report leaves us just short of seeing such a comprehensive inventory for the port. Planning for the future of cargo transit in the Los Angeles Basin requires an understanding of these figures. Just how much diesel exhaust is released in the port itself by ships, trains, trucks and dockside equipment? And how much more is released as these vehicles carry cargo in and out of the harbor?

Reading the report suggests that port-related shipping contributes to an overwhelming portion of the area’s airborne cancer risk. Solid figures would help us understand the seriousness of the problem and plan for modernizing the shipping industry to clean up our air.

The figures would also help us seek methods of mitigating the pollution problem and might suggest that we need to limit port expansion until diesel pollution solutions are put in place.

Tom Politeo is acting chair of the Sierra Club’s Harbor Vision Task Force. To reach him, call