In an asthma action plan, what peak flow measurement indicates a patient is in the green zone?

The green zone on an asthma action plan represents a state of well-controlled asthma, where the patient's peak flow measurements fall within a specific range indicating adequate respiratory function. A peak flow measurement of 80-100% of the patient's personal best signifies that asthma is under control, allowing for normal activities without significant restrictions. In this zone, the patient should feel well, experience few or no symptoms, and have minimal need for rescue medications. This reflects optimal lung function and indicates that the current asthma management plan is effective.

In contrast, measurements below this range could signify worsening asthma or an increased risk of an exacerbation, which is why maintaining peak flow readings in the green zone is crucial for the patient's health and daily functioning.