Table 4– Effect per logged unit increase of indoor nitrogen dioxide (NO₂) on daily lung function measures in children during the winter of 2006

Lung function measurement	Child days n	Subjects n	Effect size	95% CI
Evening FEV₁ mL	22516	346	-13.21	-26.03– -0.38
Morning FEV₁ mL	21335	337	-17.25	-27.63– -6.88
Evening PEFR L·min⁻¹	22518	346	-0.97	-2.29–0.36
Morning PEFR L·min⁻¹	21619	338	-1.33	-2.69–0.02

FEV₁: forced expiratory volume in 1 s; PEFR: peak expiratory flow rate.