Exposure to environmental tobacco smoke is associated with increased r
espiratory morbidity in young children, but few studies have assessed
such exposure objectively by urinary cotinine measurements. 501 childr
en aged 1-5 years, a random 5% sample of children attending an outpati
ent clinic, were classified as exposed or nonexposed to environmental
tobacco smoke with a cut-off of 10 ng cotinine per mg creatinine in ur
ine. Exposed children were 3.5 times (95% Cl 1.56-7.90, p<0.0024) more
likely to have increased respiratory morbidity (three or more episode
s during the previous 12 months) than non-exposed children after adjus
tment for potential confounding factors.