b'Chapter hapterExercise Induced Asthma?At rest, you generally breathe through your nose. The nose warms and moistens the air.When exercising, you tend to breathe faster and through your mouth. The mechanism in the mouth to warm and moisten the air is less effective than that in the nose. This means that colder, drier air reaches the small airways causing water loss and cooling. This is thought to irritate and tighten the airways of people with asthma. Exercise is a common trigger that affects up to 90% of people with Asthma. It is a trigger that should be managed and not avoided.Epidemic thunderstorm asthma?Epidemic thunderstorm asthma events are thought to be triggered by an uncommon combination of high grass pollen levels and a certain type of thunderstorm, resulting in large numbers of people simultaneously developing asthma symptoms over a short period of time.Pollen grains from grasses get swept up in the wind and carried for long distances. Some can burst open and release tiny particles that are concentrated in the wind just before the thunderstorm. These particles are small enough to be inhaled deep into the lungs which in turn can trigger breathing difficulty (asthma symptomswheezing, breathlessness, tightness in the chest / coughing)It is thought that the grass pollen grains and allergens are removed from the air by the rain from the thunderstorm.Whole grass pollen grains are relatively large and can in some susceptible people cause irritation of the eyes, nose and throat, resulting in what is commonly known as hay fever.Those at increased risk of epidemic thunderstorm asthma include people with asthma or past history of asthma. People with undiagnosed asthma or seasonal hay fever (who may or may not have asthma) are also at increased risk.Medical Emergencies 181'