Reported Asthma Symptom Intensity during Exposure to Aerosolized Florida Red Tide Toxins

Florida red tides are naturally occurring blooms of the marine dinoflagellate, Karenia brevis. K. brevis produces natural toxins called brevetoxins. The brevetoxins become part of the marine aerosol as the fragile, unarmored cells are broken up by wave action. Inhalation of the aerosolized toxin results in upper and lower airway irritation. Symptoms of brevetoxin inhalation include: eye, nose, and throat irritation, coughing, wheezing, chest tightness, and shortness of breath. Asthmatics appear to be more sensitive to the effects of brevetoxin. This study examined data from 97 asthmatics exposed at the beach for 1 hour to K. brevis blooms, and on separate occasions when no bloom was present. In conjunction with extensive environmental monitoring, participants were evaluated by questionnaires and performed pulmonary function testing before and after beach exposure. A modified Likert scale incorporated into the questionnaire was used to create symptom intensity scores for each individual pre- and post-beach exposure. Exposure to a Florida red tide significantly increased the likelihood that the reported intensity of asthma symptoms increased; no significant changes were seen during an unexposed period. This is the first study to examine the intensity of reported effects on asthmatics after a 1 hour exposure to brevetoxin aerosols.