Although a variety of classification schemes have been introduced to describe asthma in the workplace and streamline efforts to study the disease, it is important to understand that the evaluation and treatment of affected individuals, for the most part, remains the same. Occupational asthma has been defined as asthma induced by exposure in the working environment to airborne dusts, vapors, or fumes, with or without preexisting asthma.2,3 It includes the terms “sensitizer-induced asthma” and “acute irritant-induced asthma,” the latter coined “reactive airways dysfunction syndrome” (RADS), which refers to a type of occupational asthma for which there is no latency and no immunologic sensitization. The terminology is reserved for when a single high-dose irritant exposure has occurred.4 The term “work-related asthma” can be used to include occupational asthma, RADS, or an aggravation of preexisting asthma (also known as “work-aggravated” or “work exacerbated” asthma). Other diagnoses are occasionally confused with occupational asthma or may coexist with it. One example includes “sick building syndrome,” which has been described in certain individuals who work in buildings with alleged variation in temperature, humidity, or lighting that have been associated with development of upper respiratory irritation, rhinitis, and occasionally nonspecific symptoms involving the skin and nervous system.5 Individuals who manifest upper airway symptoms from chemical odors like perfumes or cleaning agents are relatively common6 and do not necessarily have asthma7; they may represent a variety of illnesses somewhat poorly defined and include an overactive perception of irritants (referred to as sensory hyperreactivity8), but not necessarily a significant airway response to methacholine challenge testing.6,9,10 Vocal cord dysfunction (irritable larynx syndrome)11 and eosinophilic bronchitis12 are clinical syndromes that may be associated with patients presenting after workplace exposures with wheezing, dyspnea, or cough, but are not considered occupational asthma.