Red tide refers to a harmful algal bloom (HAB) caused by microscopic algae that multiply to higher-than-normal concentrations in marine waters. In Florida and the Gulf of Mexico, the primary organism responsible for these blooms is Karenia brevis, a type of dinoflagellate. These natural phenomena can sometimes discolor the water, giving rise to the term “red tide,” though the water’s appearance can vary. Red tides have been documented in these regions for centuries, occurring annually in late summer or fall.
How Red Tide Triggers Coughing and Other Respiratory Issues
Karenia brevis produces natural neurotoxins called brevetoxins. When waves break near the shore, these microscopic algae cells can rupture, releasing the brevetoxins into the air as tiny particles or aerosols. People near affected beaches can then inhale these airborne toxins, which irritate the respiratory tract. Common respiratory symptoms include coughing, sneezing, throat irritation, a runny nose, wheezing, and shortness of breath. Symptoms usually lessen or disappear once a person leaves the affected area, though those with pre-existing respiratory conditions like asthma or COPD may experience more severe or prolonged effects.
Beyond Respiratory Symptoms: Other Health Impacts
Beyond respiratory irritation, red tide exposure can cause other health effects. Direct contact with water or airborne toxins may lead to skin irritation, such as rashes or a burning sensation, and eye irritation, including stinging or redness; wash affected areas thoroughly with fresh water if this occurs. Another potential health impact comes from consuming contaminated seafood, particularly shellfish like oysters, clams, and mussels. These filter-feeding organisms can accumulate brevetoxins in their tissues, leading to a condition known as Neurotoxic Shellfish Poisoning (NSP) if consumed by humans. Symptoms of NSP can include gastrointestinal issues, such as nausea, vomiting, or diarrhea, and neurological symptoms like tingling in the fingers and toes; fortunately, commercially available shellfish are generally safe because state agencies closely monitor harvesting areas and test for toxins before sale.
Minimizing Your Exposure and Protecting Your Health
To reduce exposure to red tide toxins, staying informed about current conditions is important, and individuals can check local red tide forecasts and status reports provided by environmental agencies. Avoiding affected beaches and coastal areas, especially when winds are blowing onshore, can help prevent inhalation of airborne toxins, and staying indoors with windows closed and using air conditioning with properly maintained filters can also limit exposure. For those with asthma or other chronic respiratory conditions, it is advisable to consult a healthcare provider for an action plan and to keep prescribed medications readily available. If symptoms persist or worsen after leaving the area, seeking medical attention is recommended. Pets can also be affected by red tide, so it is advisable to keep them away from impacted areas and prevent them from playing with dead fish or foam.