Jeremy Wirick, 9, has been back in school for less than two months, but he has already had several asthma attacks. A recent attack happened on October 2, after he pushed himself too hard in gym class. Running, power walking, jogging and push-ups took their toll. When Jeremy got home an hour or two later, he was out of breath. He needed to use a nebulizer, a machine that helps send medicine quickly to the lungs, to get his breathing back to normal. Asthma attacks like Jeremy increase in September and October. More than six times as many asthma sufferers who are elementary-school age need hospital treatment in the fall as in the summer. Experts believe many factors can contribute to back-to-school asthma. Kids get together in close spaces, they start passing viruses around. A viral infection can cause an asthma attack. There are also certain fall allergies that can cause attacks. Exercise is another common cause of an attack. Besides, the stress of school can make asthma worse. Parents can play a big role in helping kids with asthma start the school year right. Dawne Gee's10-year-old son, Alexander, has had asthma since he was a baby. Before the school year starts, she tells school workers in writing about her son's asthma. The Gees live in Kentucky, which has passed laws allowing students to carry their asthma medication with them at school. Alexander's mom makes sure he has his inhaler with him when he goes to school and that he keeps it on hand at all times. In Delaware, where Jeremy lives, kids are allowed to carry their inhalers at school. The American Lung Association says that about 6.2 million American children suffer from asthma. Asthma is the chronic   illness that causes students to miss the most days of school. There are many things that schools can do to help students control their asthma The passage lists many factors that cause asthma attacks except  _  .
A viral infection unhealthy habits certain fall allergies physical exercise