The obstruction could be within the middle and the small airways, as indicated by the low values of the forced expiratory flows (FEF25
, FEF50, FEF75, and FEF25-75).
(86) found associations between chronic residential N[O.sub.2] exposure and lung function to be stronger among Roman girls than boys 9-14 years of age; mean [FEV.sub.1] and FEF25
75 decrements were approximately four times greater in girls than boys, corroborating other studies (82,83,103,108-112).
Table 16 shows that statistically there is no significant (p>0.05) difference in the pulmonary function parameters in between smokers and passive smokers, except for FEF25
and FEF50 (p<0.01).
, FEF50, and FEF75 are measures of the speed at which air exits the lung when 25%, 50%, and 75% of the FVC, respectively, remains in the lung.
In the study of Ren et al., the pulmonary function parameters including, FVC, FEV1, FEV1/FVC, PEFR, FEF25
, FEF50, decreased significantly with age in both male and female subjects.