Historically, human civilizations formed near rivers because rivers provided water, fertile soil, and food.
Today, many rivers, including in India, are heavily polluted by cities and factories, turning them into polluted sewers.
Scientists in California studied how pollutants from rivers can enter the air after flowing into the ocean.
They tracked pollutants in the Tijuana River near the U.S.-Mexico border by sampling seawater and air along the coast.
The study looked for 12 common pollutants found in wastewater, like sunscreen chemicals, tire additives, prescription drugs, pesticides, and illegal drugs.
They found higher pollution levels in river water than in other seawater, and the air near the river was the most polluted.
Pollutants like sunscreen ingredient octinoxate and drug methamphetamine were found in both water and air, coming from the same source.
They estimated that 1 km of polluted coastline can release large amounts of these chemicals into the air that people breathe.
Globally, polluted coasts could release tens of thousands of tons of sunscreen chemicals and other pollutants into the atmosphere yearly.
While the amounts inhaled near rivers might be small, the long-term health effects on coastal communities who breathe this polluted air are unknown.
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