Abstract

Irritant-Induced Asthma and Reactive Airways Dysfunction Syndrome (RADS)

Stuart M Brooks

Irritant-induced asthma affects about one-fifth of workers with the diagnosis of 'occupational asthma'. There are believed to be two types of irritant-induced asthma. Single exposure-type of irritant-induced asthma occurs when a person inhales a very high concentration of an irritant gas, vapor or fume to manifest newly-developed asthma symptoms plus nonspecific airway hyperresponsiveness within 24-hours following the exposure. In contrast, repeated exposure irritant-induced asthma evolves when a purportedly genetically predisposed individual is repeatedly exposed to non-massive levels of an irritant gas, vapor or fume (or as a mixture) over a few days, weeks or months and eventually develops clinical asthma. The treatment of RADS is similar to the treatment afforded patients suffering from an acute inhalational injury. Aerosolized bronchodilators are essential for treating acute bronchoconstriction. Likely, oral corticosteroids are not effective. There is no human study showing efficacy of oral corticosteroids in the treatment of RADS. Inhaled steroids have been found effective in reducing airway hyperresponsiveness in a case considered to be RADS.