Under the practice witnessed recently by a Neon Tommy investigative team, a clean-burning rig transports cargo a short distance from the port's gates where it is met by a second rig, which does not meet rigorous air standards.

The state Air Resources Board, which enforces clean-air measures statewide, vowed to take aim at truckers next year who try to move goods in California in trucks that do not meet new emissions standards.

Port of L.A. officials sent letters to 22 companies whose trucks made 10 or more port entrances in a day in December 2009. The letters demanded an explanation as to why the trucks made so many trips.  

Neon Tommy sought copies of the letters and of the companies' responses in a formal request filed under the California Public Records Act, but port officials refused to release the information. "Upon completion of this investigation, staff will submit our findings to the Executive Director, and thereafter send you a copy along with posting the information on our website," wrote Diana Henderson of the community relations division.  

The Port of L.A. also refused to identify the companies involved.   

Chris Cannon, director of the port's Clean Truck program, said 40 trucks entered the port 10 or more times a day in December. He acknowledged that clean trucks could be swapping cargo with old trucks even after making only one port entrance.   

He said Port of L.A. officials are not responsible for problems outside their gates.   

"We're not a regulatory body. What we're really trying to do is influence what's happening here at our port terminals and on our property," said Cannon. "And we know that switching containers, in terms of within their own companies, there's nothing we can do about that."  

The Ports of L.A. and Long Beach, both located at the San Pedro Bay, started the Clean Truck Program in October 2008 in an effort to rid the ports and surrounding communities of polluting trucks, and clean up L.A. skies, by banning polluting trucks from the ports in a phased process.   

The health dangers posed by the trucks include an increased risk of cancer and asthma, contributing to the San Pedro Bay ports' nickname as the "diesel death zone."   

The state Air Resources Board currently works with local governments and law enforcement to ensure trucks near ports abide by regulations, including emissions standards, by doing random inspections.   

Those enforcement practices will be geared up when the state phases in its new rule banning 1994 to 1999 model year trucks, starting in 2013. The new policies will also require that trucks made before 1994 use an emission filter starting January 1, 2011.   

State officials appear optimistic about their ability to enforce the new policies. "A lot of people think this truck swapping [drayoff] practice is something that cannot be addressed, but it can be in different ways," said Paul Jacobs, the chief of enforcement for mobile sources at the Air Resources Board.     

To combat truck swapping, state inspectors will randomly stop trucks at border crossing checkpoints, much like it does now.

"We think we'll be able to wrap our arms around it," said Jacobs. "These bumps are something we can address. We have much bigger challenges."  

But foiling the truck swapping practice might be a bigger "bump" than the state anticipates.

Neon Tommy observed truck exchanges at two locations outside port gates: the Clean Truck Center, a place where truckers receive information about the Clean Truck Program and other port regulations, and outside the Long Beach Pier A terminal at a turn-off surrounded by "No Cargo Drop" signs. 
  

VIDEO: Watch a truck swap happen near the ports.

At both locations the swaps happened within a matter of minutes. One truck just arrived from the port, dropped its trailer and pulled away. Another truck picked up the cargo and the drivers scurried away once they saw the Neon Tommy team peeking at them from behind a taco truck.    

The team suspects truck swaps also happen regularly at privately owned trucking yards. One yard on Quay Street in Wilmington, which allowed the Neon Tommy team to visit but asked not to be named, has its clean fleet drop cargo off starting about 4 p.m. 
  

"The Nike warehouse in Ontario, and other warehouses, are full right now," said the vice president of the trucking company, when asked why the trucks leave their cargo in the yard instead of taking it to its final destination. 
  

Angelo Logan, executive director of the East Yard Communities for Environmental Justice in Commerce, believes the truck swapping takes place on a large scale at transloading stations, warehouses used by truckers to consolidate cargo and prepare loads for train shipments. These spots, located along major freeways, are convenient and make the exchange easy.   

"It's that type of thing that if you see right in front of your office, it must be happening a lot," said Logan, who said he saw a truck swap in the median across the street from his City of Commerce office.    

And many port truck drivers seem to agree.    

"I don't know what [port officials] are looking at," said Buena Park truck driver Pani Hunt, waiting in his truck near the port. "If they come out and sit down here they'll see it. It's happening right outside the gates. They gotta be kidding."   

With Mayor Antonio Villaraigosa's prodding, the Port of L.A. launched the Clean Trucks initiative in 2008 and appeared to be on its way to scrubbing the air at the country's largest port. It banned pre-1989 models and offered incentives for buying newer and cleaner rigs to replace many of the 16,000 trucks doing business there every day. 
  

The incentives include extra loading fees for trucks that fail to meet 2007 EPA standards and emit significantly more diesel emissions.  
  

A Neon Tommy investigation published in December showed that some truck companies avoid the fees and the cost of upgrading their fleet by sending new trucks to pick up cargo at the port and older trucks to haul it through nearby neighborhoods and along L.A. freeways.  

The more truck companies send their clean trucks to do circles around the port, and the more dirty trucks continue to haul cargo through the 710-corridor and other freeways, the less effective the Clean Truck Program is at improving community health and air quality.   

Despite the truck swapping problem, the Port of L.A. and the mayor's office still continue to claim the program has reduced truck diesel emissions by 70 percent. As outlined in the December Neon Tommy article, port officials base the 70 percent statistic off a rate formula instead of actual air monitoring station data.   

Five months ago the port did release a general air monitoring report with analysis up to April 2008. The report includes seven months of data that overlap with the first year of the Clean Truck Program. 
  

When comparing the May 2006 - April 2007 time period to the May 2007 - April 2008 time period, one can see a drop in elemental carbon, an indicator of diesel emissions, ranging from 35 to 23 percent. Clearly not the 70 percent the mayor touts, but still a significant cut. The Port of L.A. attributes the reduction to the economic slowdown--2009 cargo volumes were down 16 percent--and to their Clean Air Action Plan.  

The clean air plan began in 2006 and includes the Clean Truck Program and other port initiatives focused on cutting diesel polluters besides trucks, such as cargo handling equipment. 
  

"But ultimately the major source of diesel emissions is diesel trucks," said Philip Fine, atmospheric measurement manager of the South Coast Air Quality Management District.  

Andrea Hricko, of the Southern California Environmental Health Science Center, wrote in an e-mail to Neon Tommy, "It's difficult to sort out the reason behind the decreases in air pollution levels during the [2007-2008 time period]; that is, what part is CAAP and what part is decrease in imports."  

VIDEO: Andrea Hricko discusses the Clean Truck Program

Environmental groups continue to be concerned about diesel emissions despite the recent data. And they see truck swapping as counterproductive to cleaning up L.A.'s skies.  

"One way to prevent this practice is for the port to have the authority to investigate claims of trucking swapping and to punish [companies] who engage in this kind of deceitful practice." said Jessica Lass, spokeswoman for the Natural Resources Defense Council.  

Logan agrees and says the port should put in some type of mechanism to monitor where clean trucks go for their first destination. Their first stop should be farther away than the Port of L.A. truck yards and local transloading stations, at the very least, he said.  

But Port of L.A. officials remain optimistic about the future of the current program. "We expect 7,500 clean trucks to be operating in the port by this Spring," said Phillip Sanfield, Port of L.A. spokesman, "making more clean trucks available for short hauls and thereby even further reducing the need to switch trucks."

VIDEO: Trucks make drops of their cargo trailers

Reach reporter Madeleine Scinto here. Reach reporter John Guenther here. Join Neon Tommy's Facebook fan page or follow us on Twitter.