Peak Flow Meter: Using the Zone System
What 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 is determined by checking and recording your peak flow twice a day for 2 weeks while your child is healthy. Your health care provider will help you figure out the appropriate number range for each zone. Many peak flow meters come with a sticker to mark the zones.
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 and your child is not having asthma symptoms.
Your child should:
- continue to take his preventive medicine 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 health care 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 (rescue) medicine as prescribed.
- Take note of anything that may have caused the asthma to get worse (for example, forgetting to take medicine or being exposed to cigarette smoke).
If your child is often in the yellow zone, it means his asthma is not under good control. Talk to your health care provider about adjusting your child's medicine.
Red Zone: If the 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.
You should:
- Give your child the quick-relief medicine as prescribed by your health care provider. Check with your health care provider about how long you should wait to seek help if the quick-relief medicine does not return your child to the yellow or green zones.
- Call 911 if your child is having significant difficulty breathing or talking. Seek medical advice (call your health care provider or go to the emergency room).
