Problem due to narrowing of air passage can be classified as a reversible airway problem caused by the spasms of the small airways of the lungs. These spasms, coupled with an increase in mucous production, cause air to be trapped in these small airways making breathing difficult.

Problem due to narrowing of air passagetics have extra sensitive airways. Problem due to narrowing of air passage attacks are most often triggered by an allergic reaction from exposure to various stimuli, such as chemicals, animal dander, certain foods, and pollens and from exposure to irritants such as cigarette smoke. Attacks may also result from emotional upset, exercise and excitement.