Table 3—

Prevalence of recent respiratory disorders by indoor exposure level of particulate matter(PM10) and CO2, and associations of respiratory disorders with exposure levels (reference: low level)

LowElevated#p-valueConventional logistic regression modelsTwo-level hierarchical regression models
Crude OR (95% CI)Adjusted OR+ (95% CI)Adjusted OR+ (95% CI)
PM10 μg·m−3
 Wheeze11.813.8ns1.20 (0.65–2.22)1.22 (0.51–2.91)0.98 (0.93–1.04)
 Dry cough at night20.838.6<0.0012.39 (1.49–3.86)***1.21 (0.63–2.31)0.89 (0.27–2.96)
 Rhinitis28.631.9ns1.17 (0.76–1.82)0.72 (0.38–1.36)0.59 (0.22–1.57)
CO2 ppm
 Wheeze11.913.9ns1.20 (0.72–2.01)1.24 (0.55–1.03)1.52 (0.68–3.39)
 Dry cough at night21.040.0<0.0012.52 (1.69–3.76)***2.99 (1.65–5.44)**3.32 (1.21–9.09)*
 Rhinitis25.934.1<0.051.47 (1.01–2.16)*2.07 (1.14–3.73)*1.76 (0.71–4.38)
  • #: PM10 >50 μg·m−3, CO2 >1,000 ppm. : first level, child; second level, classroom. +: analysis accounted for passive exposure to tobacco smoking at home, sex, age, PM10 (increment: 10 μg·m−3), and CO2 (increment: 100 ppm). ns: not significant. *: p<0.05; **: p<0.01; ***: p<0.001. p-values were calculated using Chi-squared test.