An asthma action plan is a written plan of what to do if you or your child has an asthma attack. The green zone of the asthma action plan is where a person with asthma wants to be every day. When in the green zone:

• The peak expiratory flow is 80% to 100% of the person's personal best measurement. To find 80% of your personal best, multiply your personal best measurement by .80. For example, if your personal best flow is 400, then 80% of that is 400 times .80, which is 320.
• The person does not have any symptoms of an asthma attack.
• The person is able to do his or her usual activities and can sleep without having symptoms.

If you or your child continues to stay in the green zone for several weeks, your health professional may reduce the amount of daily asthma medication.