An ARB investigation showed that Antelope Valley Transit Authority personnel failed to test, measure, record and maintain records, and were cited for excess diesel particulate matter emissions for their fleet. The law requires owners of California-registered truck and bus fleets to regularly inspect their vehicles to ensure that their engine emissions meet state air quality standards.  

"Compliance with emissions recordkeeping and state smoke emission standards is a key component in cleaning up the air in California," said ARB Chairman Mary Nichols. "Transit agencies serve a large number of people who ride the bus every day that are negatively affected by these harmful emissions."

In January 2009, Antelope Valley Transit Authority agreed to pay $17,500 in penalties: $13,125 went to the California Air Pollution Fund that provides funding for projects and research to improve California's air quality;  $2,187.50 went to the Peralta Community College District to fund emissions education classes conducted by participating California community colleges; and the remaining $2,187.50 went to the California Pollution Control Financing Authority to fund low-interest loans for owners of off-road diesel-powered construction vehicles. 

Diesel exhaust contains a variety of harmful gases and over 40 other known cancer-causing substances. In 1998, California identified diesel exhaust as a toxic air contaminant based on its potential to cause cancer, premature death and other health problems. New research links vehicle exhaust and lung cancer mortality in trucking industry workers exposed to diesel and other types of vehicle emissions with increasing years of work.