Figure 1.

The scheme represents the universe of the 8 locations in the study and the final spirometries obtained.

Notes: Test Session Quality Grades: A= 3 + acceptable maneuvers, and FEV₁ and FVC match within 150 mL; B= 3 + acceptable maneuvers, and FEV₁ and FVC match within 200 mL; C= 2 + acceptable maneuvers, and FEV₁ and FVC match within 250 mL; D= only 1 acceptable maneuver, or the FEV₁ or the FVC from the best 2 acceptable within 250 mL; F= no acceptable maneuvers.

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