Passive smoking and childhood asthma. Urinary cotinine levels in children with asthma and in referents
Passive exposure to tobacco smoke was assessed in children with asthma (age 3-15) and in referents. There was statistically significantly (P less than 0.0005) higher excretion of the nicotine metabolite, cotinine, in the urine of 49 children with asthma (geometric mean 10 ng/ml) compared with 77 referents (4.8 ng/ml). Maternal smoking was statistically significantly more prevalent among the asthma