Table 6 Associations between incident wheezing symptoms for 3-day mean concentrations (lag 2–4) of air pollutants in 110 children living within a 5 km radius of the central monitor

	Age 0–1	Age 1–2	Age 2–3	Age 0–3
	OR* (95% CI)	OR (95% CI)	OR (95% CI)	OR (95% CI)
n†	102	81	70	103
PM₁₀ (μg/m³)	1.32 (0.95 to 1.82)	1.20 (0.87 to 1.67)	0.78 (0.52 to 1.16)	1.11 (0.88 to 1.39)
n	76	78	70	95
UFP_NC§ (particles/m³)	2.46 (1.04 to 5.84)‡	1.09 (0.61 to 1.94)	0.40 (0.21 to 0.76)‡	0.92 (0.63 to 1.34)
n	103	81	70
NO₂ (ppb)	1.84 (1.07 to 3.17)‡	1.36 (0.90 to 2.05)	0.92 (0.62 to 1.35)	1.28 (0.99 to 1.65)
n	103	81	70	104
NO_x (ppb)	1.46 (0.97 to 2.21)	1.37 (0.98 to 1.91)	0.93 (0.67 to 1.28)	1.23 (1.00 to 1.51)‡
n	103	83	70	104
CO (ppm)	1.40 (0.83 to 2.36)	1.32 (0.75 to 2.34)	0.81 (0.46 to 1.40)	1.18 (0.85 to 1.63)

CO, carbon monoxide; NO_x, nitrogen oxide; NO₂, nitrogen dioxide; PM₁₀, particulate matter <10 μm in diameter; UFP_NC, ultrafine particles.
*Odds ratios estimated in a single-pollutant model per log IQR of a pollutant and 3-day mean (lag 2–4 days) adjusted for age, gender, exposure to smoking, paternal asthma history, temperature and season.
†Number of COPSAC children in the model.
‡p<0.05.
§Total concentration of ultrafine particles 10–700 nm in diameter (95% of total concentration comes from particles <100 nm).