Physical exertion and exercise is a trigger for 8 out of 10 people with asthma. Pollen is a trigger for 5 out of 10 people with asthma. Fur or feathers from pets are triggers for 8 out of 10 people with asthma. There are number of other substances, like insecticides, paint fumes, grain, flour dust and wood dusts, that are known to trigger asthma attacks. Even a change in the weather can trigger an attack.
Emotional upset can also act as a trigger.