A Peak Flow Meter is a simple, handheld device used to measure how fast air can be expelled from the lungs. It is commonly used by individuals with respiratory conditions like asthma to monitor their lung function. By blowing into the meter, users can obtain a reading that indicates their peak expiratory flow rate (PEFR), helping them assess their breathing capacity. Regular use of a peak flow meter can help identify changes in lung function, allowing users to take proactive steps in managing their condition. It is often part of an asthma action plan, guiding patients on when to seek medical help or adjust their medication based on their readings.