Findings Demonstrate Importance of Equity-Driven Action. September 15, 2024 – SACRAMENTO – Californians are breathing far less pollution from vehicles than they were 25 years ago. Exposure to fine particulate matter (PM2.5) from cars, trucks and other vehicles has dropped by 65%, according to a new study by the California Environmental Protection Agency’s (CalEPA’s) Office of Environmental Health Hazard Assessment (OEHHA); University of California, Berkeley (UC Berkeley); and University of Washington. Particulate Matter 2.5 is a type of pollution comprising very small particles in the air that are 2.5 micrometers or less in diameter.