Algae are plant-like organisms that sustain marine life. They contribute to the food chain and to the oxygen that keeps water bodies healthy. But sometimes, when conditions are right—warm water and increased nutrients—certain algae can quickly grow and overpopulate. These foam- or scum-like masses are called blooms, and can be pushed to the shore by winds, waves, tides and currents. Some blooms release toxins that make ecosystems, animals and people sick: scientists call these harmful algae blooms or HABs. In Florida, we find HABs along our saltwater, freshwater and brackish water bodies.
HABs are temporary and usually happen in late summer or early fall. They can last three to five months, sometimes longer, and can affect small and large areas.
As some HABs decay they release a bad odor. Hydrogen sulfide is one such foul smelling gas that is a naturally occurring, colorless product of decomposition. It can smell like rotten eggs. The human nose is very sensitive and can smell the unpleasant odor of hydrogen sulfide at very low levels. The Florida Department of Health completed testing in 2016 and 2018 for the presence of hydrogen sulfide in the air during HAB events. The results from both studies indicated very low, non-hazardous levels. The smell can cause respiratory irritation, but is not harmful to your health. If you are irritated by the strong odor or have breathing difficulties move away from the source of the smell. Symptoms should end a short time after the odor disappears or the exposure to the odor ends.
HABs and Animal Health Resources