The patented dual colour sliders on the asmaPLAN+ define the management colour zones set by
the healthcare professional for the asthmatic to follow.
100% is the asthmatic's best. The yellow zone will typically be set to start at 80% of the
asthmatic's best while the red zone will typically start at 60%. Variability of PEFR of
greater than 20% should alert the asthmatic to a possible asthma attack.