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New research shows dirty ocean water is fouling air in Imperial Beach

San Diego researchers say the sewage polluting the ocean off South County beaches is also polluting the air.

Findings published in Environmental Science and Technology concluded that pollution is being lifted into the air when the ocean churns into waves near shore and creates aerosols.

Researchers concluded their findings by sampling the air in Imperial Beach between January and May 2019. They found aerosols from the ocean waves that contained bacteria and other contaminants present in the Tijuana River.


Air monitors collected tainted airborne samples suggesting that the contamination risk from the cross-border pollution is not limited to just water contact.

Which means, people near the beach and pier were exposed to contaminated aerosols.

“We have an infrastructure problem that’s causing not only polluted water, but research demonstrates that people in coastal communities like Imperial Beach are exposed to coastal water pollution even without entering that water,” said Matthew Pedergraft, the paper’s lead author and a recent graduate from the Scripps Institution of Oceanography.

Big wave action during storms creates the most sea spray, increasing the amount of bacteria-carrying aerosols.

And there is no shortage of pollution in the water this winter.


An estimated 13 billion gallons of sewage-tainted water had crossed the border, flowed through the Tijuana Estuary and out into the ocean since the beginning of this year.

Pollution warning signs, linked to the cross-border flows, were up at South County beaches for the majority of the previous year and for an earlier part of this year.

“We’ve shown that up to three-quarters of the bacteria that you breathe in at Imperial Beach are coming from aerosolization of raw sewage in the surf zone,” said Kim Prather, a Scripps Institution of Oceanography researcher who studies aerosols. “People worry about swimming and surfing in it, but not about breathing it in, even though the aerosols can travel long distances and expose many more people than those just at the beach or in the water.”

Researchers are still trying to determine whether the airborne bacteria poses a health threat like the bacteria does when it is in the water.

There are research projects in the works that will track hospital admissions, and teams plan to regularly swab lifeguards, surfers and residents who live near the beach to get a better understanding of the impacts of the airborne pollution.

If there are health risks, it may lead to warnings about air quality when the weather churns up a lot of sea spray.

New research shows dirty ocean water is fouling air in Imperial Beach

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