Scientists have discovered that harmful chemicals from Florida‘s blue-green algae blooms are becoming airborne, potentially affecting people who live miles away from contaminated water.
A new study reveals that toxins produced by cyanobacteria, commonly known as blue-green algae, are being released into the air in Southwest Florida, raising concerns about respiratory exposure to these harmful compounds.
Researchers from Brain Chemistry Labs in Wyoming partnered with the nonprofit Calusa Waterkeeper to place air samplers across multiple locations in Southwest Florida.
Every single sample collected contained a neurotoxin called 2,4-DAB, which is produced by cyanobacteria. This is the same toxin previously found in the brains of beached dolphins in Florida’s Indian River Lagoon, where the animals showed signs of Alzheimer’s disease.
Cyanobacteria are ancient organisms that helped create Earth’s oxygen-rich atmosphere billions of years ago.
However, when waterways become overloaded with nutrients like nitrogen and phosphorus, often from agricultural runoff or poorly treated sewage, these bacteria can multiply rapidly, forming dense blooms that release toxins into the environment.
Scientists have long focused on contaminated food and drinking water as the primary routes of exposure to the toxins, but the new findings suggest that breathing contaminated air may be an equally important pathway.
Harmful algae toxins are linked to a range of health issues, from immediate respiratory and gastrointestinal problems to long-term neurological conditions including Alzheimer’s disease, amyotrophic lateral sclerosis (ALS) and Parkinson’s disease.
Florida’s blue-green algae toxins are becoming airborne, reaching people miles from contaminated water (stock)
To find out if algae toxins can become airborne, researchers developed a special device called ADAM, short for Airborne Detection for Algae Monitoring.
This portable air sampler was designed to collect air at ‘breathing height,’ about five to six feet off the ground, which is the level where people would actually inhale it.
The device uses two collection methods: a glass fiber filter that captures particles, and a liquid ‘impinger’ that traps any toxins dissolved in the air.
Between July and December 2021, the team placed these samplers at multiple locations across Southwest Florida, specifically along the lower Caloosahatchee River, within the Matlacha Preserve areas and at sites like the Cape Coral Yacht Club, running each one for 24 hours at a time.
At each site, they also collected water samples to compare the toxins found in the air with those found in the water.
The air samples were then analyzed for a range of toxins. Because Florida’s Gulf Coast also experiences red tide blooms from Karenia brevis, they also tested for brevetoxins — respiratory irritants linked to red tide.
The study, published in the journal Toxins, found that even when there were no visible algae blooms in the water, toxins were still present in the air.
Of the 21 water samples collected, 62 percent showed no signs of cyanobacteria or algae at the surface.
Pictured is the ADAM sampler’s collection system, showing the glass fiber filter and liquid impinger that work together to capture both particle-bound and dissolved toxins from the air
This map shows the locations where researchers collected air and water samples across Southwest Florida. The study focused on areas along the Caloosahatchee River and Matlacha Pass, with samples taken at multiple sites between July and December 20
Yet despite the lack of blooms, air samples regularly contained detectable levels of toxins.
The device collected both particles and dissolved compounds, leading researchers to conclude that people may be chronically exposed to low concentrations of these toxins through inhalation.
‘Even though we can avoid contaminated food and water, preventing exposure through breathing is far more difficult,’ lead scientist Dr James Metcalf said.
The air filters detected a red tide toxin in just five percent of samples. But other toxins were far more common. One appeared in a third of samples, and after more sensitive testing, detection rates hit 100 percent.
That suggests people are breathing in low levels of these compounds even when no blooms are visible.
Water samples contained an even broader mix of toxins linked to health issues. Liver toxins were found in 29 percent of samples, nerve toxins in 43 percent and respiratory irritants in 38 percent.
Only one sample, which contained an actual bloom of Microcystis aeruginosa, a type of blue-green algae, showed high levels of microcystin-LR — the most common and well-studied cyanotoxin. For the most part, toxin concentrations were low, consistent with the absence of significant blooms.
There was no clear link between what was in the air and what was in the water at the same location. Airborne toxins were detected even when the water showed little to no algae.
Pictured is the pump that draws air through the system at two liters per minute
This suggests that aerosols can travel from distant sources or that even small amounts of algae can release toxins into the air.
The frequent detection in air samples raises concerns about chronic, low-level exposure.
‘These data suggest that you don’t need to be close to toxic blooms to be exposed through breathing,’ Metcalf said.
‘We continue to find cyanobacterial toxins in the air, as in our study of dust blown from the exposed lakebed of the Great Salt Lake in Utah.’
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One of the most concerning long-term health risks is the potential link between the neurotoxin BMAA and neurodegenerative diseases such as ALS or Parkinsonism dementia complex (PDC), which is a rare neurodegenerative condition that combines symptoms of ALS, Parkinson’s disease and dementia.
This connection has been observed in primate models and cell cultures, where BMAA exposure can trigger harmful effects such as excitotoxicity and protein aggregation in the brain.
Microcystins are also being investigated for their ability to cross the blood-brain barrier and potentially contribute to Alzheimer’s and Parkinson’s diseases by causing neuroinflammation and other cellular damage.
However, more research is needed to fully understand these links, and a 2017 EPA review concluded that current data does not definitively prove BMAA causes brain disease in humans.
Toxins like brevetoxin from red tides are well-known respiratory irritants. Inhaling them can cause coughing, sneezing, a runny nose, wheezing and chest tightness.
People with pre-existing conditions like asthma are particularly vulnerable. Research has shown that breathing in aerosolized brevetoxins can cause measurable decreases in lung function for asthmatics, making their symptoms noticeably worse.
Recent studies show that inhaling microcystins, which have also been found in lake and sea spray aerosols, can cause harmful airway inflammation. This inflammation is similar to a specific type of asthma and may even worsen existing inflammatory lung conditions.