A study by UC San Diego researchers reveals that pollutants found in the sewage-laden Tijuana River are ending up in the air near the U.S.-Mexico border in San Diego County.

That’s according to a study from UC San Diego’s Scripps Institution of Oceanography, published Wednesday in the journal Science Advances, which identifies the Tijuana River as the dominant source of coastal pollution in the region.

The 120-mile Tijuana River flows from Baja California into the United States and discharges millions of gallons of wastewater — including sewage, industrial waste and runoff — into the Pacific Ocean every day,