Nearly 24,000 Californians die prematurely because exposure to pollution for a long time, according to report presented Thursday to the California Air Resources Board.

Called “Methodology for Estimating Premature Deaths Associated with Long-term Exposures to Fine Airborne Particulate Matter in California, the report reads that Californians exposed to particle pollution had their lives cut short by an average of 10 years.

Based on the analysis of 60 studies worldwide, including studies by the World Health Organization, the report concluded that the microscopic particles are 70 percent more dangerous that previously thought, Bart Croes, chief researcher for the California Air Resources Board said, according to the Los Angeles Times. He also added “cities with higher rates of air pollution have much greater rates of death from cardiovascular diseases,” which is a clear sign that air pollution increases a person’s risk to die from heart attacks, strokes and respiratory-related problems. The most polluted areas around the state include the South Coast, the San Joaquin Valley and the San Francisco Bay air basins.

Trucks, passengers cars, off-road equipment and electric power generation seem to be the worst air pollutants.

The researchers warned that even small amount of polluted air can affect children, the elderly, and people with weakened immune systems.

“Particle pollution is a silent killer. We must work even harder to cut these life-shortening emissions by further addressing pollution sources head-on,” said Air Resources Board Chairman Mary Nichols.

Following results of this report, Air Resources Board unanimously voted to approve the air cleanup plan, which will curb emissions from diesel-powered trucks and buses. This plan requires final approval from the U.S. Environmental protection Agency.