Tides of Trouble: What Asthmatics and Everyone Should Know About the Risks From Sargassum (Seaweed) Along the Coastline

You’ve probably already read the ominous media reports of the coming wave of the largest Atlantic sargassum belt ever, stretching more the 5,000 miles and circling the Gulf of Mexico and mid-Atlantic. The largest masses of this class of leafy, rootless and buoyant algae, or seaweed, is expected to wash ashore along Florida’s beaches and elsewhere along the Gulf of Mexico and the Caribbean by mid-summer.

But what about health hazards to people, particularly those with asthma or other respiratory conditions? Not only can such masses of sargassum wreak havoc on nature’s ecosystems, it releases irritants like hydrogen sulfide in the air when it begins to rot about 48 hours after washing onto beaches and coastal communities.

Jose Vazquez, M.D., chief of primary care at Baptist Health Medical Group.


Jose Vazquez, M.D., chief of primary care at Baptist Health Medical Group, has seen patients on occasion with minor flare-ups from contact with sargassum or even red tide, the harmful algal blooms (HABs) that occur anywhere along the nation's coast, turning parts the water a deep red. Some HABs produce toxins that have harmful effects on people, fish, marine mammals, and birds

“Anybody that has a history of asthma, a history of any chronic respiratory issues, or history of chronic allergies, could be susceptible to large amounts of sargassum because it emits irritants in the form of a foul-smelling gas, called hydrogen sulfide,” explains Dr. Vazquez. “And it could irritate the respiratory tract and irritate your eyes and nasal passages. People that are prone to having those symptoms could be more susceptible.”

Sargassum is a class of large brown seaweed (a type of algae) that floats in island-like masses and never attaches to the seafloor. Large blooms of sargassum are not new to the Caribbean islands, the U.S. coast along the Gulf of Mexico and around Florida’s coastline. Mexico’s Yucatan Peninsula has also seen its share of waves of sargassum in recent years.

Dr. Vazquez urges people who may run across masses of sargassum along the beach to be extremely cautious, and not to allow children to play or touch the piles of seaweed.

“Anybody could be affected if you are exposed to high concentrations, or for a very long period of time,” he said. “Even if you don't have asthma or if you don't have chronic allergies, you could also be affected. And you could have some of the same symptoms: coughing, watery eyes, runny nose, maybe even shortness of breath.”

In 2011, the Atlantic Oceanographic & Meteorological Laboratory, part of NOAA (National Oceanic and Atmospheric Administration), noticed that the geographic range of the sargassum belt expanded, and massive amounts began washing ashore along islands throughout the Caribbean Sea. “Although Sargassum provides habitat, food, protection, and breeding grounds for hundreds of diverse marine species, the sudden occurrence of an unprecedented amount of this floating algae can disrupt shipping, tourism, fishing, and coastal ecosystems,” states AOML, which is headquartered in Key Biscayne, Florida.

“We know every year we get a little bit here and there,” explains Dr. Vazquez. “For whatever reason, we're getting a lot more this year. And, we know that it could have some effects depending on how much accumulates. The sargassum does have some organisms that live in it -- little jellyfish, little microscopic organisms, and those could be irritating to the skin if people come in contact with them.”

In more severe cases, especially among clean-up crews and other workers exposed to sargassum-related, airborne irritants.

“High concentration exposure could also affect the nervous system,” said Dr. Vazquez. “You could have headaches and you could have memory problems – although the majority of these recover well. But, there's been some cases of people that develop long-term neurological effects from this. We're talking about very high concentrations in closed areas, mostly people that work in industries that produce a lot of hydrogen sulfide, fertilization, plants and places like that.”

Dr. Vazquez has a general “common sense” message to everyone who comes across piles of sargassum or families that are even tempted to play in the masses of seaweed.

“For the public, it's important for them to use their common sense,” Dr. Vazquez emphasizes.  “Don't overexpose yourself to this, don't eat it, don't use it for cooking. Make sure your children don't eat it. If you have developed symptoms, then step away from it. Use your inhalers if you are asthmatic, and if you don't get better, see your doctor. This is very treatable. This doesn't lead to cancer, and it shouldn’t lead to long-term effects. But you should try and avoid exposure to it whenever possible.”

Healthcare that Cares

With internationally renowned centers of excellence, 12 hospitals, more than 27,000 employees, 4,000 physicians and 200 outpatient centers, urgent care facilities and physician practices spanning across Miami-Dade, Monroe, Broward and Palm Beach counties, Baptist Health is an anchor institution of the South Florida communities we serve.

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