TABLE 1. American Thoracic Society/European Respiratory Society spirometry quality criteria [8].

Acceptability
Free of artifacts
Cough
Glottis closure
Early termination
Submaximal effort
Leaks
Obstructed mouthpieces
Back extrapolated volume <5% of FVC or 0.15 L, whichever is greater
Expiratory time ≥ 6 s, 3 s for children or plateau in the volume-time curve or when the patient cannot or should not continue to exhale
Repeatability
A minimum of three acceptable tests should be obtained
The two largest FVC should be within .15 L of each other
The two largest FEV1 should be within .15 L of each other

Note: FVC, forced vital capacity; FEV₁ , forced expiratory volume in the first second.