There are three main triggers that can cause an asthma attack: allergens, irritants, and exercise.
Allergens are substances that can trigger an allergic reaction. They can be found in the environment, such as pollen, dust mites, or animal dander. When someone with asthma comes into contact with an allergen, it can trigger an asthma attack.
Irritants are substances that can irritate the airways and cause them to narrow. Common irritants include smoke, chemicals, and strong odors. Exercise can also be an irritant for some people with asthma.
Exercise is a common trigger for asthma attacks because it causes the body to release chemicals that can irritating the airways. Cold weather is also a trigger for some people because it causes the airways to constrict.