A peak flow meter measures how fast air moves out of the lungs. This is a good way to check changes in your airways from asthma before you may feel them. Then you can take your medicines early to stop these changes and avoid a severe asthma attack. Use a peak flow meter as directed by your doctor.

How to use your peak flow meter

1. Remove any gum or food you may have in your mouth. 
2.  Connect the mouthpiece to the peak flow meter. 
3.  Move the mark to 0 (zero). 
4.  Hold the meter with 1 hand. 
5.  Stand up or sit up straight. 
6.  Take in a deep breath. 
7.  Close your lips tightly around the mouthpiece. 



8. Blow out as hard and fast as you can for 1 to 2 seconds into the mouthpiece with 1 blow. 
9.  Write down the number on the gauge. If you cough or make a mistake, reset the mark to 0 (zero) and do it again. 
10. Repeat these steps 2 more times. Write down the highest of your 3 readings. 
11.  Clean the mouthpiece with soap and water.

What the Reading Means

Your action plan is based on zones of how bad your asthma is, called asthma severity. Your peak flow can help you find out what zone you are in. You do this by comparing your current peak flow to your personal best peak flow. 

Your personal best is your highest peak flow recorded over a 2 to 3 week period when your asthma is under control.

• Green Zone. Green means good: You want to be in the green zone every day. Green means your peak flow shows your lungs are working well. Your medicine is working, and you can go ahead with your daily activities.

Your green zone is readings above _______.

• Yellow Zone. Yellow means caution: Yellow means your lungs are working harder. Your medicine may need to be changed. Take the action your doctor has ordered for you or call your doctor. Use caution in your daily activities.

Your yellow zone is readings between _______ and _______.

• Red Zone. Red means STOP: Red means you are having breathing problems, and your asthma is not under control. Go to the doctor or call 911. You need treatment right away.

Your red zone is readings below _______.

Some meters have color markers that can be set to show your target zones. 

Your doctor or nurse can help you figure out your target zones based on your readings when your asthma is controlled. You may need to check your readings for several days and bring them with you to the doctor’s office or clinic. Your target zone may be different than another person’s because of your size, age, and lung function. 

Each meter is a little different. If you change meters, you will need to find your asthma zones using the new meter. 

Follow-up care is a key part of your treatment and safety. Make and go to all appointments and call your doctor if you have problems, questions, or concerns. Knowing your test results and keeping a list of the medicines you take is also a good idea.

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© 2005 – January 18, 2023, Health Information Translations

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Peak Flow Meter. Arabic.