The determinants of risk of chronic sequelae of high-dose exposures to inhaled irritants are not well understood.1,2 One of the obstacles to the study of this issue is the lack of predictability about when such events (eg, accidental releases of irritant gases, vapors, dusts, and fumes) will occur. Although an unimaginably horrible incident, the World Trade Center (WTC) disaster has provided the opportunity to learn much about the risk of chronic respiratory disease after massive exposures to fire smoke and a highly alkaline dust.3 Because New York City firefighters had undergone routine medical surveillance with spirometry prior to September 11, 2001, it has been possible to document with continued serial spirometry in the subsequent years that firefighter responders sustained a substantial loss of ventilatory function as a consequence of these exposures.4,5 In addition, Fire Department City of New York (FDNY) investigators have demonstrated that subgroups of firefighters have developed persistent cough, airway hyperresponsiveness, and/or airways obstruction following their response to the WTC collapse.6-8