The Florida gulf coast is experiencing a seasonal surge in red tide and health officials are warning residents and visitors about potential respiratory issues triggered by the toxic algae bloom.

The Florida Fish and Wildlife Conservation Commission reports a new outgrowth of a troubling bloom along parts of the southwest Florida coast last week, particularly around Sarasota, Charlotte, Lee and Collier counties.

The bad blooms can also be an irritant for swimmers, causing eye, skin and respiratory ailments, and are particularly dangerous to consumers of tainted shellfish. Red tide may be most severe for people with preexisting respiratory conditions, such as asthma, according to the National Oceanic and Atmospheric Administration.