Study finds the air you breathe contains bacteria from the ocean

The Scripps Institution of Oceanography at UC San Diego has found that coastal water pollution transfers to the atmosphere in sea spray aerosol, which can reach people across the land.

This according to a press release published by the institution on Thursday.

This sea spray aerosol contains bacteria, viruses, and chemical compounds from the seawater.

The study comes along at a time when an estimated 13 billion gallons of sewage-polluted waters have entered the ocean via the Tijuana River since December  2022.

“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 lead researcher Kim Prather, a Distinguished Chair in Atmospheric Chemistry, and Distinguished Professor at Scripps Oceanography and UC San Diego’s Department of Chemistry and Biochemistry. 

“Coastal water pollution has been traditionally considered just a waterborne problem. 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.”

The research team collected and analyzed coastal aerosols at Imperial Beach and water from the Tijuana River between January and May 2019. Through the use of DNA sequencing and mass spectrometry, they were able to link bacteria and chemical compounds in coastal aerosol back to the sewage-polluted Tijuana River flowing into coastal waters. 

Harmful bacteria and chemicals found

Aerosols from the ocean were found to contain bacteria and chemicals originating from the Tijuana River however this does not mean people are getting sick from sewage in sea spray aerosol. Most bacteria and viruses found in the compounds are harmless.

The authors do add that infectivity, exposure levels, and other factors that determine risk need to be further assessed through more studies.

“This research demonstrates that coastal communities are exposed to coastal water pollution even without entering polluted waters,” said in the statement lead author Matthew Pendergraft, a recent graduate from Scripps Oceanography who obtained his PhD under the guidance of Prather. 

“More research is necessary to determine the level of risk posed to the public by aerosolized coastal water pollution. These findings provide further justification for prioritizing cleaning up coastal waters.”

The researchers report their findings in the journal Environmental Science & Technology.