. 2014 Nov 14;9(11):e112933. doi: 10.1371/journal.pone.0112933

Table 8. Associations between measured environmental factors and onset (incidence) of weekly symptoms during the two-year follow-up from 2010 to 2012 (N = 1283).

Type ofexposures	Any skinSymptoms(OR 95% CI)	Any mucosalSymptoms(OR 95% CI)	Any generalSymptoms(OR 95% CI)	Any symptomsimproved ifaway from school(OR 95% CI)	Any school relatedmucosal symptoms(OR 95% CI)	Any school relatedgeneral symptoms(OR 95% CI)
Indoor climate and air pollutants in classrooms
SO₂	0.61(0.19–2.01)	0.61(0.30–1.23)	0.92(0.49–1.74)	0.70(0.33–1.48)	0.57(0.22–1.43)	0.65(0.29–1.47)
NO₂	0.87(0.59–1.28)	0.97(0.76–1.23)	0.98(0.78–1.22)	0.85(0.67–1.09)	0.94(0.69–1.28)	0.87(0.66–1.14)
O₃	0.86(0.59–1.26)	0.91(0.74–1.12)	0.91(0.75–1.10)	0.88(0.70–1.11)	0.93(0.72–1.21)	0.92(0.73–1.17)
PM₁₀	1.39(1.10–1.76)^**	1.34(1.14–1.57)^***	1.24(1.06–1.45)^**	1.01(0.84–1.22)	1.33(1.09–1.63)^**	1.26(1.05–1.52)^*
Temperature	1.49(0.28–7.80)	1.45(0.51–4.08)	1.12(0.82–1.23)	1.21(0.95–1.35)	1.17(0.98–1.33)	1.24(0.91–1.40)
CO₂	1.43(0.96–2.11)	1.59(1.23–2.06)^***	1.85(1.45–2.36)^***	1.73(1.31–2.27)^***	1.93(1.43–2.62)^***	1.87(1.41–2.48)^***
RH	1.33(0.93–1.76)	1.47(1.22–1.76)^***	1.51(1.27–1.79)^***	1.41(1.16–1.71)^***	1.65(1.33–2.05)^***	1.56(1.28–1.91)^***
Air pollutants outside the school
SO₂	2.08(1.11–3.90)^*	1.33(0.90–1.97)	1.17(0.85–1.68)	0.91(0.60–1.39)	0.93(0.55–1.58)	1.05(0.66–1.67)
NO₂	1.16(1.07–1.25)^***	2.03(1.27–3.25)^**	1.64(1.06–2.54)^*	0.90(0.54–1.51)	1.54(0.83–2.85)	1.14(0.65–1.99)
O₃	0.60(0.34–1.08)	1.11(0.75–1.65)	1.14(0.79–1.64)	1.47(0.94–2.29)	1.24(0.72–2.13)	1.51(0.92–2.48)
PM₁₀	1.22(1.07–1.40)^**	1.25(1.14–1.37)^***	1.20(1.09–1.32)^***	1.18(1.06–1.31)^**	1.33(1.20–1.47)^***	1.29(1.17–1.43)^***

Odds ratio (OR) with 95% confidence interval (CI) calculated by multiple logistic regression. Adjustment for age, gender and parental asthma or allergy, analysing each exposure variable separately.

*P<0.05.

**P<0.01.

***P<0.001.