‘Florida red tide,’ which annually hits the Florida coast due to blooms of the karenia brevis algae, produces highly potent airborne toxins that are known to cause breathing problems.

But a study from the University of Miami shows that people with asthma are much more severely affected by red tides after even a short period of exposure, with breathing difficulties lasting well beyond the time spent on the beach.

“In the normal population, inhaled aerosolized red tide toxins can lead to eye irritation, rhinorrhea, nonproductive cough, and wheezing. However, these symptoms usually subside after leaving beach areas,” said Lora E. Fleming of the University of Miami Rosenstiel School of Marine & Atmospheric Science, who led the study.

“Our study shows that red tide toxins may have a greater impact on patients with asthma, who experienced respiratory problems and decreased lung function after just one hour of beach exposure to the toxins,” she said.

The study measured the lung function of 97 people with asthma who spent at least an hour on the beach in Sarasota during an active bloom of K brevis. The asthmatics reported a “significant increase in symptoms” following exposure to the algal bloom toxins, even if using asthma medication.

The frequency and intensity of red tides is thought to have increased with higher concentrations of nutrients produced by human activities. Agricultural run-off in particular is thought to supply the nitrates and phosphates needed to ‘fertilise’ algal blooms of karenia brevis.

Goska Romanowicz

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