Asthma can be triggered by external agents, such as irritants in the atmosphere which are breathed in, or by internal reactions within the body that have been caused by an external influence. The kinds of provoking factors can be divided into two groups:
- Non-specific factors: all asthma patients are affected by a number of things that are referred to as irritants. They include exertion, cold, smoke, scents and pollution.
- Specific factors: these are irritants or allergens in the form of pollen, dust, animal fur, mould and some kinds of food. A virus or bacteria, chemical fumes or other substances at the workplace and certain medicines, eg aspirin and other non-steroidal anti-inflammatory drugs (NSAIDs), may also cause asthma.
To acquire asthma, people seem to need to have been born with a predisposition to the disease. It may not reveal itself until they have been exposed to some asthma irritants.
Smoking mothers, low birth weight, a lack of exposure to infection in early life and traffic fumes have all been associated with the increase in asthma. Less draughty houses resulting in a higher concentration of house dust mites and cooking gases may also be part of the problem.
Currently, a great deal of research looking for the genes that allow asthma to develop is being carried out. But until we can prevent asthma, we have to suppress the symptoms and try to avoid the triggers where possible.
