Scientists Find Blue-Green Algae Toxins Spread Through Air Beyond Water

Scientists have discovered that toxins produced by blue-green algae, also known as cyanobacteria, are not confined to polluted water bodies but can disperse through the air over long distances. This finding emerged from a study conducted by researchers at the Brain Chemistry Laboratories in Wyoming in collaboration with the nonprofit organization Caloosa Waterkeeper.

The study revealed that air samples collected from various locations in southwest Florida contained toxins generated by cyanobacteria. Cyanobacteria are among the oldest living organisms on Earth and contributed billions of years ago to the formation of the oxygen-rich atmosphere. However, elevated nutrient levels such as nitrogen and phosphorus in rivers and lakes—caused by agricultural runoff and untreated sewage—promote dense cyanobacterial blooms that release toxins harmful to human and animal health.

Previously, scientists believed that human exposure to these toxins occurred mainly through drinking contaminated water or consuming affected food. The new research suggests that inhaling airborne toxins represents another significant exposure pathway.

To investigate this, the researchers developed a portable device named ADAM designed to collect air samples at human breathing height. It uses a filter to capture particles and a specialized unit to gather dissolved airborne toxins.

Between July and December 2021, the team deployed these devices at multiple sites along the lower Caloosahatchee River, within the Matlacha Preserve, and at the Cape Coral Yacht Club. Each device operated for 24 hours while water samples were simultaneously collected at the same locations for comparison.

The results, published in the journal Toxins, showed the presence of the neurotoxin 2,4-DAB in every analyzed air sample, despite 62% of water samples showing no visible cyanobacterial or algal blooms. The researchers also detected other toxins at low levels in the air, while the red tide toxin brevetoxin appeared in less than 5% of samples.

The scientists noted that the persistent detection of these toxins in the air, even without obvious algal blooms, implies that humans might experience chronic exposure through respiration. These toxins may travel via airborne particles from distant sources or originate from small, visually undetectable amounts of algae.

Dr. James Metcalf, the lead scientist, stated, "We can avoid contaminated food and water, but it is much harder to avoid toxins present in the air."

Water analyses identified a variety of toxins, including liver toxins, neurotoxins, and respiratory irritants. Only one water sample showed elevated levels of microcystin-LR toxin alongside a clear bloom of Microcystis aeruginosa algae.

Exposure to algal toxins is linked to health issues ranging from coughing and respiratory irritation to neurological disorders. Researchers are currently exploring whether toxins such as BMAA and microcystin contribute to diseases like Alzheimer’s, Parkinson’s, and amyotrophic lateral sclerosis, although current evidence does not confirm a direct causal relationship in humans.

Scientists warn that individuals with chronic respiratory illnesses, such as asthma, may be particularly vulnerable to these toxins. Previous studies have indicated that inhaling certain red tide toxins can impair lung function and worsen symptoms.