Beach closures due to sewage leaking from Tijuana have become ubiquitous to life in Coronado, but new research shows it’s not just the water that’s contaminated – the air is too.
As breaking waves churn sewage-infected water, bacteria is pushed airborne, according to findings from the Scripps Institution of Oceanography at the University of California San Diego published earlier this month. Between 41 and 76 percent of bacteria in the air at Imperial Beach, depending on surf and wind patterns, is traceable to leaked sewage, the study says.
Although improvements in both Mexico and California are underway to mitigate the problem, it will likely persist after the new infrastructure is built, the study argues, because the sewage comes from multiple sources and high-flow stormwater will still be diverted to the oceans.
Further, the study says, “climate change is expected to cause more extreme precipitation events, which may further exacerbate the problem.”
An estimated 13 billion gallons of polluted water from the Tijuana River have entered the oceans since Dec. 28, 2022, according to a UCSD statement.
Just because leaked sewage from Tijuana ultimately pushes bacteria into the air, researchers caution, that doesn’t necessarily mean people are getting sick from it. Some bacteria are harmless, and exposure and infectivity are factors that play into risk. While this study established the fact that sewage-linked bacteria can become airborne, more research is needed to determine its impact on humans.
“This research demonstrates that coastal communities are exposed to coastal water pollution even without entering polluted waters,” said lead author Matthew Pendergraft in a statement. “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.”
Researchers are also working to determine how far downwind bacteria travels and whether viruses also transfer to the air in addition to bacteria. To aid in this research, Ethereum founder Vitalik Buterin donated $15 million in cryptocurrency to the university, establishing the Meta-Institute for Airborne Disease in a Changing Climate at UC San Diego.
His donation is the largest to fund open-source research on aerosols to date, and one of the largest cryptocurrency donations made to a university in history. Though the institute will be housed in the UCSD School of Biological Sciences, it will take a multidisciplinary approach, with researchers from Scripps and UCSD’s School of Physical Sciences spearheading the research.
“Working together with health care experts, infectious disease doctors, engineers, respiratory experts and scientists, we will be developing state-of-the-art measurements and computational tools to study these problems,” said Kim Prather, co-director of the new institute and distinguished chair in atmospheric chemistry and biochemistry at Scripps. “A major goal is to develop a better understanding of the production and sources of airborne bioparticles and how long they remain infectious.”
Prather is also the founding director of the Center for Aerosol Impacts on Chemistry of the Environment, which is funded by the National Science Foundation. She will co-direct the new institute with Rommie Amaro, distinguished professor of theoretical and computational chemistry, section chair of biochemistry and biophysics, and co-director of the Visible Molecular Cell Consortium at UC San Diego.
