During an asthma attack, the muscles of the airways contract, causing the airways to narrow. A peak flow meter can help detect narrowing of the airways hours or even days before any symptoms of asthma appear.

Peak expiratory flow is a test that measures a person's maximum rate of exhalation, used to test lung function and is often used in the diagnosis of asthma.

Asthma is not a rare disease, it is considered to cause many inconveniences in life. To help control the disease better, many people have proactively used popular asthma management tools today.