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Thorax 60:467-473 doi:10.1136/thx.2004.033977
  • Environmental exposure

Traffic related air pollution as a determinant of asthma among Taiwanese school children

  1. B-F Hwang1,
  2. Y-L Lee2,
  3. Y-C Lin3,
  4. J J K Jaakkola4,
  5. Y L Guo2
  1. 1Department of Health Care Administration, Diwan College of Management, Tainan, Taiwan; and Department of Environmental and Occupational Health, College of Medicine, National Cheng Kung University, Tainan, Taiwan
  2. 2Department of Environmental and Occupational Health, College of Medicine, National Cheng Kung University, Tainan, Taiwan; and Department of Internal Medicine, National Cheng Kung University Hospital, Tainan, Taiwan
  3. 3College of Dental Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
  4. 4Institute of Occupational and Environmental Medicine, University of Birmingham, Birmingham, UK
  1. Correspondence to:
    Dr Y L Guo
    Department of Environmental and Occupational Health, National Cheng Kung University, Tainan, Taiwan; leonguomail.ncku.edu.tw
  • Received 27 August 2004
  • Accepted 3 February 2005

Abstract

Background: There is evidence that long term exposure to ambient air pollution increases the risk of childhood asthma, but the role of different sources and components needs further elaboration. To assess the effect of air pollutants on the risk of asthma among school children, a nationwide cross sectional study of 32 672 Taiwanese school children was conducted in 2001.

Methods: Routine air pollution monitoring data for sulphur dioxide (SO2), nitrogen oxides (NOx), ozone (O3), carbon monoxide (CO), and particles with an aerodynamic diameter of 10 μm or less (PM10) were used. Information on individual characteristics and indoor environments was from a parent administered questionnaire (response rate 93%). The exposure parameters were calculated using the mean of the 2000 monthly averages. The effect estimates were presented as odds ratios (ORs) per 10 ppb changes for SO2, NOx, and O3, 100 ppb changes for CO, and 10 μg/m3 changes for PM10.

Results: In a two stage hierarchical model adjusting for confounding, the risk of childhood asthma was positively associated with O3 (adjusted OR 1.138, 95% confidence interval (CI) 1.001 to 1.293), CO (adjusted OR 1.045, 95% CI 1.017 to 1.074), and NOx (adjusted OR 1.005, 95% CI 0.954 to 1.117). Against our prior hypothesis, the risk of childhood asthma was weakly or not related to SO2 (adjusted OR 0.874, 95% CI 0.729 to 1.054) and PM10 (adjusted OR 0.934, 95% CI 0.909 to 0.960).

Conclusions: The results are consistent with the hypothesis that long term exposure to traffic related outdoor air pollutants such as NOx, CO, and O3 increases the risk of asthma in children.

Footnotes

  • This study was partially supported by grant #NSC92-2302-B-006-028 from the National Science Council and grant #DOH90-TD-1138 from the Department of Health. Yung-Ling Lee was also a recipient of the Taiwan National Health Research Institute MD-PhD Predoctoral Fellowship (DD9102N). Jouni Jaakkola was partly supported by The Yrjo Jahnsson Foundation.