Table 6

Risk of low lung function (FEV₁ <80% predicted) in preschoolers aged 4.5 years in relation to exposure levels of air pollutants

Exposure	N low/normal lung function	RR	(95% CI)	p Value
Benzene
Entire pregnancy	112/453	1.13	(0.93 to 1.36)	0.208
First trimester	112/453	1.10	(0.92 to 1.33)	0.270
Second trimester	112/453	1.22	(1.02 to 1.46)	0.027
Third trimester	112/453	1.15	(0.96 to 1.37)	0.134
First year of life	111/448	1.03	(0.86 to 1.23)	0.768
NO₂
Entire pregnancy	112/454	1.18	(0.85 to 1.63)	0.324
First trimester	112/454	1.10	(0.81 to 1.48)	0.545
Second trimester	112/454	1.30	(0.97 to 1.76)	0.080
Third trimester	112/454	1.21	(0.89 to 1.64)	0.222
First year of life	111/449	1.01	(0.74 to 1.36)	0.962
Recent exposure*	112/454	1.31	(0.87 to 1.97)	0.193
Current exposure†	108/415	1.13	(0.84 to 1.51)	0.410
NO_x
Recent exposure*	112/454	1.16	(0.91 to 1.49)	0.230
Current exposure†	108/415	1.05	(0.90 to 1.22)	0.553

All models adjusted for area of study, birth weight, maternal social class, maternal education level, maternal smoking in pregnancy and paternal smoking in pregnancy, environmental tobacco smoke 0–14 months, and lower respiratory tract infections 0–14 months.
*One-year average before lung function testing.
†One-week average before lung function testing.
NO₂, nitrogen dioxide; NO_X, nitrogen oxides; RR (95% CI), Relative Risk and 95% CIs for anIQR increase in exposure estimated by log-binomial regression.