Carbon monoxide pollution and lung function in urban compared with rural Mongolian children.

Background And Objective: Mongolia is experiencing rapid urbanization, and this presents a unique opportunity to assess the effects of this process on the lung health of children.

Methods: Two cross-sectional cohorts of school-age children (5-15years of age) from the capital (Ulaanbaatar) (n=116) and a rural district (Tuv Aimag) (n=108) were studied. Demographical information, exposure to tobacco smoke, and ambient and exhaled CO, as well as FEV(1) and FEF(25-75%) were recorded for each child.

Results:   Ambient CO levels were threefold higher in the capital city than in the rural Aimag (0.63 vs 0.21 parts per million (ppm), P<0.00005), while exhaled CO was twofold higher (0.94 vs 0.47ppm, P<0.00001). Rural Mongolian children were 6cm shorter on average than urban children. However, when adjusted for age and height, FEV(1) was 140% of predicted in rural children compared with 106% of predicted in urban children (P<0.00001). There was no significant difference in small airway expiratory flow (FEF(25-75%) ; 104 in urban children, 100 in rural children, P=0.63).

Conclusions:   'Normal' FEV(1) was actually 40% higher in rural Mongolian children than in urban children, suggesting that the FEV(1) of apparently healthy children living in urbanized societies may in fact not be normal, but may instead reflect the deleterious effects of air pollution in cities, as indicated by increased levels of both environmental and exhaled CO.