Occupational asthma is a type of asthma which is identifiable by limited passage of air through the respiratory pathways, as well as hyper-responsiveness of the pathways as a result of being exposed to certain environmental conditions experienced at the patient's workplace. Occupational asthma is usually not triggered outside one's workplace.

Occupational asthma comes in two different variants. The first variant causes the chest muscles to tighten, breath to come in short gasps, wheezing sounds to come out when breathing and fits of dry coughing. These symptoms occur after being exposed for some time to one's work environment.
 
The second variant of occupational asthma develops instantly, and its occurrence is usually attributed to an exceptionally high presence of allergens in the occupational environment. Its symptoms can differ significantly from those exhibited in case of the first variant of occupational asthma. The second variant is also known as Reactive Airways Dysfunction Syndrome (RADS).

Like all other variants of asthma, occupational asthma can be caused by a diverse range of biological and chemical substances, including the likes of colophony fumes, toluene di-isocyanate, flour, wood dust and skin flakes shed by animals. Its advent is mostly attributed to organic substances.