Reports of airway irritant effects from Florida red tide have been documented since 1844 (Baden et al., 2005). In general, it is well established that persons inhaling marine aerosols containing polyether brevetoxins (PbTxs) produced by the dinoflagellate, Karenia brevis (K. brevis), can exhibit either upper and/or lower airway symptoms (see Backer and McGillicuddy, this issue). Upper-airway symptoms include cough, sneezing, rhinorrhea (runny nose), a burning sensation in the nose and throat, and watery eyes (Kirkpatrick et al., 2004). Lower-airway symptoms include chest tightness and wheezing and/or shortness of breath, all of which reflect difficulty in breathing (Kirkpatrick et al., 2004). Normal individuals, as well as those with pre-existing airway diseases such as asthma (i.e., susceptible populations), can be affected, although anecdotal evidence has indicated that susceptible populations are at greater risk (Asai et al., 1982).