With asthma, you have a persistent condition with irritation = inflammation in the airways. The reason is that there is a narrowing of the airways and a contraction of the smooth muscle in the lungs. This is due to an inflammatory reaction. It causes coughing and shortness of breath. The lungs become very sensitive to cold air, strong smells, infections, air pollution, pollen, animal hair and the like. Allergies and hay fever are the most common causes of asthma.