The spirometric measurements were carried out at schools according to ATS criteria,
using a Minato AS-505 portable electric spirometer (Minato Ltd., Tokyo, Japan).
The spirometers were calibrated before and after each field
Effects of air pollution on children’s lung function growth 1513
work session using a 2-L calibration syringe. Study subjects
were measured in a sitting position with a nose clip. After
a demonstration, each child was asked to perform the test
until three satisfactory readings were obtained. The output
from the curve with the largest FVC and forced expiratory
volume in 1 s (FEV1) was chosen for analysis. Prior to the
test, each child’s height (standing erect without shoes) and
weight (in light clothes) were also measured.