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Attorneys for the Natural Resources Defense Council say those who are living near the freeways are breathing the dirtiest air.
A coalition of environmental groups filed a petition Thursday with the Ninth Circuit Court of Appeals demanding comprehensive monitoring of air quality along freeways.
According to the L.A. Times, the 710 Freeway averages more than 12,000 vehicles per hour, and 25 percent of them are diesel trucks going to and from the ports.
The lawsuit against the EPA aims to overturn vehicle emissions limits for Southern California. Environmental groups say monitors are far from the interstates where diesel particulates and the cancer risk are greatest.
They say the South Coast Air Quality Management District is prohibited by federal law to measure pollution near known sources, such as the freeways, when it calculates regional air pollution.
Environmental groups hope their lawsuit can bring change at the federal level, and that will eventually help clean up the air locally.