Half the cases develop in childhood. Asthma symptoms may go away as children become adults. They may come back as adults get older.

Asthma symptoms vary from one person to the next. Common symptoms are shortness of breath, cough, wheezing, and chest tightness. These symptoms may mean a severe flare-up.

Triggers include allergens, strong odors, and respiratory infections. Others include weather changes, medicines, GERD (gastroesophageal reflux disease), air pollution, food, exercise, strong emotional reactions, and secondhand smoke, the America Lung Association says.

You should take these steps to manage your asthma even when you don't have symptoms.

It's important to get regular exercise. Swimming is good for people with asthma. Other activities recommended include short break periods, according to the American Academy of Allergy, Asthma, and Immunology. Some people with asthma may need to use inhaled medicines before exercise.