• air pollution;
  • airway hyperresponsiveness

Background: There has been an increase in allergic diseases as a result of increased air pollution emanating from traffic and various industries.

Objective: This study evaluated the association between air pollution and airway hyperresponsiveness in a cross-sectional study of a cohort of 670 children, aged 10–13 years.

Methods: We measured spirometry and conducted allergic skin tests and methacholine challenge tests in 670 schoolchildren. The methacholine concentration causing a 20% fall in FEV1 (PC20) was used as the threshold of airway hyperresponsiveness (AHR). Thresholds of 16 mg/dl or less were assumed to indicate AHR.

Results: All of the schoolchildren had normal pulmonary function. Of the children, 257 (38.3%) had AHR. There was a significant increase in AHR in schoolchildren living near a chemical factory [45.0% (138/306), 6.50 ± 0.48] compared to those in rural [31.9% (52/163), 9.84 ± 0.83] and coastal [33.3% (67/201), 7.17 ± 0.68] areas. Atopy was significantly more prevalent near the chemical factory vs the coastal and rural areas [35.6% (109/306) vs 27.3% (55/201) and 23.3% (38/163), respectively, P < 0.007]. Schoolchildren with atopy had lower PC20 than those without atopy (5.98 ± 0.60 vs 8.15 ± 0.45, P < 0.001). Positive allergy skin tests and living in a polluted area were risk factors in multivariate analyses adjusted for sex, parents’ smoking habits, age, body mass index, nose symptoms and lung symptoms (odds ratio for location = 2.4875, confidence interval 1.6542–3.7406, P < 0.000; odds ratio for allergy skin test = 1.5782, confidence interval 1.1130–2.2379, P < 0.0104).

Conclusion: Our findings demonstrate that more children living in polluted areas have airway hyperresponsiveness than do those living in less polluted areas.