Asthma is a common chronic condition of the airways.
People with asthma experience episodes of wheezing, breathlessness and chest tightness due to widespread narrowing of the airways. The symptoms of asthma are usually reversible, either with or without treatment. The severity of asthma ranges from mild, intermittent symptoms, causing few problems for the individual, to severe and persistent wheezing and shortness of breath. In a few people with asthma the disease has a severe adverse impact on quality of life and may be life-threatening.
While the underlying causes of asthma are still not well understood, there are a number of factors that may increase the risk of developing asthma.
Among those with the condition, airway narrowing and symptoms can be triggered by:
- viral infections
- exercise
- exposure to specific allergens such as:
- house dust mites
- pollens
- mould spores
- animal dander
- irritants such as:
- tobacco smoke and other air pollutants
- some food additives.
- occupational exposures to:
- specific allergens
- irritants such as: