Nearly Half of US Breathes Unhealthy Levels of Pollution—Cars and Trucks Largely to Blame
Union of Concerned Scientists
MAY 21, 2025
It presents air pollution data at the county-level for two pollutants, deadly fine particulate matter (PM 2.5 ) and ground-level ozone. is emitted directly from the tailpipes of gasoline and diesel vehicles, while ozone and even more PM 2.5 From 2000 to 2020, national PM 2.5 Secondary PM 2.5
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