Table 3– Association between prevalence of respiratory symptoms and long-term average concentration of particulate matter with a 50% cut-off aerodynamic diameter of 10 μm (PM₁₀)

	Mean OR (95% CI)
	Age-sex adjusted	Fully adjusted^#
Wheeze	1.03 (0.95–1.11)^¶	1.01 (0.95–1.09)
Asthma	0.99 (0.92–1.08)	1.03 (0.97–1.10)
Bronchitis	1.06 (0.94–1.21)^¶	1.08 (0.98–1.19)^¶
Phlegm	1.16 (1.02–1.31)^¶	1.15 (1.02–1.30)^¶
Nocturnal cough	1.15 (1.00–1.32)^¶	1.13 (0.98–1.29)^¶
Morning cough	1.16 (1.02–1.32)^¶	1.15 (1.02–1.29)^¶
Sensitivity to inhaled allergens	1.01 (0.90–1.13)^¶	1.02 (0.93–1.11)
Hay fever	1.18 (0.96–1.44)	1.20 (0.99–1.46)
Itchy rash	1.04 (0.98–1.11)	1.07 (0.96–1.19)^¶
Woken by wheeze	1.04 (0.94–1.14)^¶	1.01 (0.92–1.12)
Allergy to pets	1.18 (0.95–1.46)^¶	1.18 (0.96–1.45)^¶

Odds ratios (ORs) are combined effect estimates from single pollutant models calculated from country-specific estimates using random effects model. Mean ORs and 95% confidence intervals are given per 10 μg·m⁻³ increase in PM₁₀. ^#: adjusted for age, sex, maternal education, paternal education, household-crowding, current parental smoking, mother smoking during pregnancy, gas-cooking, unvented gas/oil/kerosene heater, mould, nationality, birth order and “ever had a pet”; ^¶: evidence of between-study heterogeneity (p<0.10).