SACRAMENTO, Calif. — A new controversial California Air Resources Board report concludes that there is a causal relationship between exposure to fine particle pollution and premature death.

The study found that about 9,000 people in California die prematurely each year as a result of exposure to fine particle pollution, which is produced by of a variety of sources including particles in the exhaust of diesel exhaust.

"This study is further evidence that we are on the right track, and CARB will continue to work with truckers and equipment owners to clean up diesel emissions, improve our air quality and protect public health. CARB is committed to reducing this staggering statistic because one premature death is one too many," said CARB Chairman Mary Nichols.

California already has some of the toughest emissions rules of any jurisdiction in North America, but the report suggests that more emission reductions must be achieved through CARB regulations of mobile sources, including trucks.

The CARB report and its methodology were based on recent assessments by the U.S. EPA.

However, the report has detractors.

In fact, a well-respected 36-year veteran UCLA researcher was fired, he claims, because he doubted the science regarding diesel particulate matter and public health.

Even though no one at CARB challenged his work, Dr. James Enstrom says he was terminated on a technicality.

"If there is an ongoing controversy in science, you don’t put out regulations that cost billions of dollars," he told media.