Workplace respiratory irritants and asthma.

Workplace respiratory irritants can have a variety of effects in relation to asthma. Very high exposures can cause new-onset asthma (reactive airways dysfunction syndrome or irritant-induced asthma) with or without concurrent sensitization, e.g., to diisocyanate. Aggravation of underlying asthma can result from moderate exposures. Adjuvant or other effects enhancing the risk of sensitization to high molecular weight allergens have occurred with chronic low-moderate exposures. Enhancement of airway responsiveness on a short-term basis can be produced by ozone and biological irritants such as endotoxin and beta 1-3 glucans. Production of nonasthmatic responses such as hyperventilation and vocal cord dysfunction can mimic asthma symptoms. Controversy exists as to whether moderate irritant exposures can cause asthma or long-term worsening of underlying asthma.