Table 5– Change in interrupter resistance (R_int) for an interquartile range (IQR) increase in long-term air pollution concentration: sensitivity analysis

	NO₂			PM_2.5			Soot
	n	*βIQR**	*seIQR**	n	*βIQR**	*seIQR**	n	*βIQR**	*seIQR**
Model 2 (main model)	765	0.0245*	0.0123	765	0.0399*	0.0150	765	0.0337*	0.0132
Model 2 + intervention	765	0.0246*	0.0123	765	0.0403*	0.0151	765	0.0339*	0.0132
Model 2 + cough on test day	765	0.0227^#	0.0124	765	0.0379*	0.0151	765	0.0318*	0.0132
Model 2 + technician R_int	765	0.0283	0.0184	765	0.0432^#	0.0247	765	0.0376^#	0.0198
Model 2 + region of the country	765	0.0248	0.0192	765	0.0400	0.0271	765	0.0368^#	0.0210

Change in R_int (kPa^.s^.L⁻¹) calculated by multiplying regression slope (β) from multiple linear regression with IQRs (table 2). Model 2: corrected for age, sex, height, nationality, siblings, mother smoking during pregnancy, pets, mould/damp spots, smoking inside child's home, use of gas for cooking, geyser without outlet, parental allergy and education of parents, temperature, relative humidity and season. PM_2.5: particles with a diameter of <2.5 μm. *: p<0.05; ^#: p<0.10.