State officials confirmed Monday that the waters off the coast of Palm Beach County have tested positive for red tide.
Dozens of beaches across the county were shut down this weekend after people reported having breathing problems and skin irritation.
Lifeguards wore face masks Monday as they ushered people away from the beaches. Businesses along the beaches said they have seen a drop in customers.
Officials said the beaches would reopen Wednesday, but advised people with respiratory problems to avoid the area. Tests were also conducted in Deerfield Beach in Broward County, but the results won't be available until Wednesday.
Red tide is a natural occurrence that happens due to the presence of nutrients in salt water and dinoflagellates.
Officials with the Florida Fish and Wildlife Conservation Commission said the tests in Palm Beach County showed medium concentrations of the Karenia brevis organism, a dinoflagellate.