The disorder is a chronic inflammatory condition often linked to allergies, in which the airways develop increased responsiveness to various stimuli, characterized by bronchial hyper-responsiveness, inflammation, increased mucus production, and intermittent airway obstruction. The symptoms of asthma, which can range from mild to life threatening, can usually, be controlled with a combination of drugs and lifestyle changes.
Many environmental factors are known to precipitate attacks of asthma. These factors are all either allergens or irritants. Allergic factors play a role in many, but by no means every, case of asthma. Some factors and triggers that can cause an asthma attack are: dust, animal dander, pollen, an infection, breathing cold air, exertion, reactions to certain medications, workplace chemicals and cigarette smoke.
Asthma is increasingly becoming a public health concern because of its rapidly increasing prevalence, affecting up to one in four urban children. Susceptibility to asthma can be explained in part by genetic factors, but no clear pattern of inheritance has been found. Asthma is a complex disease that is influenced by multiple genetic, developmental, and environmental factors, which interact to produce the overall condition.