Miami Beach and the Keys could get loads of seaweed. It’s smelly and can cause these symptoms

Florida is bracing for a massive, smelly load of seaweed to wash upon its shores.

The brown seaweed is expected to start piling up in the Florida Keys in the next few days, with Miami Beach slated to become a hot spot later in the sargassum season, which runs from March through October.

It tends to have a nasty, rotten egg smell and can sometimes cause health problems for people with chronic respiratory conditions.

Here’s what to know:

Why does seaweed smell so bad?

The brown seaweed that washes up on Florida beaches is known as Sargassum. Once it washes ashore, the seaweed starts to rot and releases hydrogen sulfide gas, which smells like nasty, rotten eggs.

What type of health problems can hydrogen sulfide cause?

The gas seaweed releases when it rots — hydrogen sulfide — can irritate your eyes, nose and throat. Tiny sea creatures living in the seaweed, like jellyfish and sea lice, can also cause skin rashes and blisters.

“If you have asthma or other respiratory illnesses, you will be more sensitive to hydrogen sulfide. You may have trouble breathing after you inhale it,” according to the Florida Department of Health in Monroe County.

People who are exposed to hydrogen sulfide for long period of times in an enclosed space, like workers in wastewater treatment industries, can get ill and experience various symptoms such as dizziness, headache, an upset stomach and apnea, according to the Centers for Disease Control and Prevention.

“However, hydrogen sulfide levels in an area like the beach, where large amounts of air flow can dilute levels, is not expected to harm health,” according to Monroe’s health department. There’s also no indication the gas causes cancer in humans.

Health officials in the Keys are recommending people who live near the beach keep their windows and doors closed. They’re also recommending anyone with asthma or other respiratory problems stay away — or reduce their time — at the beach if there is seaweed. If you don’t want to risk getting stung by an animal living in the seaweed, don’t touch it and stay away.

And before you think about taking some seaweed home to cook with it, think again. The health department said it’s not a good idea because sargassum might contain “large amounts of heavy metals like arsenic and cadmium.”

And remember, if you’re having severe trouble breathing, call 911.

What are the seaweed hot spots in Miami-Dade?

Some Florida beaches might have more seaweed than others. And while it’s possible Florida might see a record bloom of seaweed this season, it doesn’t mean all of the beaches will be full of stinky seaweed every week through October. The sargassum will show up on the beaches in clumps when the tide is high and the wind is blowing from east to west, pushing the seaweed toward shore.

Miami-Dade County has identified four seaweed hot spots on local beaches: beaches in Haulover just north of Haulover Cut; beaches in Bal Harbour just south of Haulover Cut; Miami Beach between 26th Street and 31st Street; and the beaches alongside South Pointe jetty.

Miami Herald staff writer Nicolas Rivero contributed to this report.