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Peak Flow Meter: Using the Zone System

is the zone system?
The zone system is an easy way to check if your child's asthma is in good control, if your child needs to take medicine, or if you need to get help right away. The peak flow meter can be marked with three colored zones (green, yellow, and red). The zones are different for each person and are based on your child's personal best peak flow reading. Your child's personal best peak flow is determined by checking and recording the peak flow twice a day for 2 weeks while your child is healthy. Your healthcare provider will help you figure out the right number range for each zone. Many peak flow meters come with a sticker to mark the zones. An asthma action plan is a written plan developed by your healthcare provider to help you manage asthma and prevent your child's asthma attacks. It is based on your child's peak flow zone.

What do the zones mean?
The colored zones on the peak flow meter are modeled after the traffic light.

  • Green means good control (80 to 100% of personal best reading).
  • Yellow means caution (50% to 80% of personal best reading)
  • Red means danger (less than 50% of personal best reading)

Green zone: When the reading is in the green zone, it means your child's asthma is under control.

Your child should:

  • continue to take his long-term control medicine (controller) as prescribed
  • continue with everyday activities (school, play, sports)

If your child has stayed in the green zone for at least 3 months, talk to your healthcare provider about possibly reducing your child's medicines.

Yellow Zone: If the reading is in the yellow zone, it means your child is probably having asthma symptoms or may soon be having symptoms (asthma attack). Your child may be having difficulty with normal activities or having symptoms at night.

Your child should:

  • Take his quick-relief (reliever) medicine as prescribed.

You should:

  • Take note of anything that may have caused your child's asthma to get worse (for example, forgetting to take medicine or being exposed to cigarette smoke).

If your child's peak flow is often in the yellow zone, or stays in the yellow zone after treatment, it means his asthma is not under good control. Talk to your healthcare provider about adjusting your child's medicine.

Red Zone: If the peak flow reading is in the red zone, it means your child's asthma is seriously out of control. He is probably having serious asthma symptoms such as extreme shortness of breath (even at rest), chest tightness, wheezing, and trouble talking.

Your child should:

  • Take his quick-relief medicine (reliever) as prescribed.

You should:

  • Call your healthcare provider or go to emergency room. Note: Check with your healthcare provider about how long you should wait to seek emergency help if the quick-relief medicine does not return your child to the yellow or green zones.
  • Call 911 if your child is having severe trouble breathing and his medicine is not helping.