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The National Center for Environmental Health’s Health Studies Branch (HSB) at the Centers for Disease Control and Prevention (CDC) is the response branch for the Center. HSB conducts rapid epidemiologic investigations in response to outbreaks that are believed to have environmental causes and responds to natural and technologic disasters.

Harmful Algal Blooms - Gateway to Health Communication - CDC

Harmful algal blooms can produce toxins that are dangerous to people, animals, and the environment. Learn what harmful algal blooms are, how you and your pets should keep away from them, and what CDC is doing about them.

A harmful algal bloom (HAB) occurs when toxin-producing algae grow excessively in a body of water. Algae are microscopic organisms that live in aquatic environments and use photosynthesis to produce energy from sunlight, just like plants. The excessive algal growth, or algal bloom, becomes visible to the naked eye and can be green, blue-green, red, or brown, depending on the type of algae.