A new study out of Harvard University says the chances of a trucker dying from heart disease are nearly 50 percent higher than the general U.S. population, diesel exhaust being the likely cause.

According to the Sacramento Bee, the findings are part of the largest and most comprehensive study to look into the effects of diesel engine emissions on trucking industry workers nationwide, including long-haul truck drivers, but also office clerks, engine mechanics and dockworkers exposed to the exhaust.

The researchers examined the jobs and medical histories of more than 54,000 male Teamsters union members who had worked for one of four national trucking companies from 1985 through 2000.

Cynthia Garcia, a state air pollution scientist, told the Bee the findings are important not only for transportation workers but also for people who commute in heavy diesel-fueled traffic or who live or work near truck terminals, ports and railroad yards.

Garcia presented the research in front of the California Air Resources Board, which regulates diesel exhaust as a cancer-causing agent.  She said the study is further evidence on the risks of diesel exhaust and the need for cleaner-burning fuels and engines for diesel-powered vehicles and equipment.

The Harvard study was published in the August edition of Environmental Health Perspectives, a scientific journal.

According to the Bee, the researchers were surprised by the higher death rates for heart disease, particularly among truck drivers - 49 percent - and dockworkers, 32 percent. The lung cancer death rate also was elevated among drivers and dockworkers, by 10 percent.

The study focused on diesel soot and other breathable exhaust particles, but did not examine individual exposures to the exhaust or workers lifestyles and diet, which could explain the higher number of heart attacks and lung cancer.

The study said the trucking industry workers overall were heavier smokers than the general population but not so much as to explain the elevated lung cancer and heart disease, according to the Bee.