Nearly three in 10 surfers admit they knowingly surf during health advisories - nearly the same amount that chooses not to surf during periods of elevated bacteria. About 40 percent of surfers said they were unaware if they had ever surfed during an active health advisory.

The data can help public officials better warn surfers of potential health risks, said Anna Harding, co-author of the study and professor in OSU's College of Public Health and Human Sciences.

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"Beach advisories for bacteria are not having their intended effect of dissuading surfers," Harding said. "The lack of awareness about advisories - and willingness to take risks surfing in water that may be contaminated - suggests the need to educate surfers about behaviors that make them vulnerable to illness."

More than 500 surfers from the Pacific Northwest provided information for OSU's study and spanned a wide range of ages, incomes, surfing frequency and other demographics.

Of those surveyed by OSU, nearly 40 percent reported ear infections or discharge at some point during surfing; 30 percent, a sore throat or cough; 16 percent experienced diarrhea; 10 percent, fever; and 7 percent had vomited. Results were consistent across experience levels and were not lessened by showering after surfing.

Surfing during and after rain also led to higher rates of waterborne illnesses. Surfers are attracted to large waves that accompany a storm, but rain can send fecal bacteria from stormwater outfalls into the Pacific Ocean, as well as flush harmful microbes from animal feces present in streams and rivers onto beaches.

Surfers cannot avoid swallowing water - which can include harmful bacteria - during wipeouts, Harding said. They ingest 10 times more ocean water than swimmers, about 170 milliliters a day, or half a can of soda, she added.

Health advisories are posted online and on signs around the West Coast. But not every beach entrance has a warning sign, and many surfers do not notice them, said Dave Stone, co-author of the study and an environmental and molecular toxicology professor in OSU's College of Agricultural Sciences.

Image of surfers on a white beach via Shutterstock.

Read more at Oregon State University.