Asthma experts have a wealth of evidence, which shows that asthma is a growing worldwide problem. Yet, they do not have a clear explanation why it has leapt to epidemic proportions over the last 20 years. Many suggestions have been put forward - stress, diet, dust mites, better living standards, increased pollution, better diagnosis, the list goes on and on. However, it could be that the overuse of these drugs simply identifies severe asthmatics who have a greater risk of dying. When you experience an episode of asthma, it is known as an attack.
Many people have asthma without even knowing it.
This may be your only symptom. This depends on your sensitivity to the specific trigger and how hyper-reactive your airways are at a given time. It can occur instantaneously and will nearly always occur within 30 minutes to 2 hours of exposure to the trigger. Some parts of the immune system, however, only cause symptoms about five hours after initial exposure. Asthma becomes worse when you are exposed to triggers.