The World Trade Center (WTC) disaster and its recovery work involved a range of hazardous occupational exposures that have not been fully characterized but can be reasonably assumed to have the potential to cause mucosal inflammation in the upper and lower airways. A high prevalence of lower airway disease (LAD) symptoms was reported by several early surveys. Clinical studies further categorized the diagnoses as irritant-induced asthma (of subacute onset), nonspecific chronic bronchitis, chronic bronchiolitis, or aggravated preexistent obstructive pulmonary disease in a substantial proportion of patients. Risk factors for WTC-related LAD included early (on September 11 or 12, 2001) arrival at the WTC site and work at the pile of the collapsed towers. Cigarette smoking (but not atopy) also seemed to be a risk factor for LAD. No data thus far suggest an increased incidence of neoplastic or interstitial lung disease, but ongoing surveillance is clearly necessary.