ABSTRACT
<p><b>OBJECTIVE</b>To study the indoor environmental factors associated with the prevalence of asthma and related allergies among school children.</p><p><b>METHODS</b>A cluster sampling method was used and the ISAAC questionnaire was conducted. A total of 4612 elementary students under Grade Five of 7 schools were enrolled in the survey for the impact of indoor environmental factors on the prevalence of asthma and related allergies in several urban and suburban schools of Beijing.</p><p><b>RESULTS</b>A total of 4060 sample were finally analyzed including 1992 urban and 2068 suburban. The prevalence of wheeze, allergic rhinoconjunctivitis and atopic eczema in the past 12 months was 3.1% (61/1992), 5.3% (106/1992), 1.1% (22/1992) among urban children while 1.3% (27/2068), 3.1% (65/2068), 1.0% (22/2068) among suburban children respectively. The prevalence of wheeze and allergic rhinoconjunctivitis of the past 12 months in urban were both significantly higher than that in suburban (χ(2) = 14.77, 11.93, P < 0.01). The incidences of having asthma and eczema ever among urban children (5.3% (105/1992), 29.4% (586/1992)) were significantly (χ(2) = 39.03, 147.22, P < 0.01) higher than that among suburban (1.7% (35/2068), 13.8% (285/2068)). Although the distributions of indoor environmental factors were similar in both areas, passive smoking and interior decoration had different influence on the prevalence of asthma and related allergies among school children in the two areas. The significant impact of passive smoking on having asthma ever among suburban children was observed (OR = 2.70, 95%CI = 1.17 - 6.23) while no significant result in urban (OR = 1.06, 95%CI = 0.71 - 1.58); the percentage of interior decoration was 84.0% (1673/1992) among urban children and 80.0% (1655/2068) among suburban children, there was significant impact of interior decoration on the prevalence of having eczema ever among urban children (OR = 1.57, 95%CI = 1.17 - 2.10) but no significant results were found in suburban sample (OR = 1.06, 95%CI = 0.76 - 1.48).</p><p><b>CONCLUSION</b>The prevalence of asthma and related allergies among school children is much higher in urban areas than that in suburban areas and the indoor environmental factors such as passive smoking and interior decoration may differently explain the prevalence of asthma and related allergies in the two areas.</p>