As the differences between the annual mean concentrations of PM10 and SO2 were small between MPD and LPD,
we combined the data from the two districts and compared
the lung function growth of these children with those of
children in the HPD. Results showed a similar pattern as the
above findings: a faster growth rate for FEV1, FEF25e75, and
FEF25 in boys living in the two districts than those in the
HPD (mean (SE): 0.27 (0.01) vs. 0.22 (0.02) for FEV1; 0.37
(0.04) vs. 0.29 (0.05) for FEF25e75; and 0.17 (0.03) vs. 0.09
(0.04) for FEF25, respectively). The differences in FEV1
and FEF25 were, however, only borderline insignificant
( p Z 0.069).