The effects of low-level environmental tobacco smoke exposure on pulmonary function tests in preschool children with asthma.

Objectives: Though parents of children with asthma smoke, they often avoid smoking in their homes or near their children, thus limiting exposure. It is not known if such low-level environmental tobacco smoke (ETS) results in measurable exposure or affects lung function. The objectives of this study were to measure urinary cotinine in preschool children with asthma, and to examine the relationship between low-level ETS exposure and pulmonary function tests (PFTs).

Methods: Preschool children with asthma were enrolled. Parents completed questionnaires on ETS exposure and asthma control, urinary cotinine concentrations were measured and PFTs were compared between subjects with and without recent ETS exposure.

Results: Forty one subjects were enrolled. All parents denied smoking in their home within the last 2 weeks, but 14 (34%) parents admitted to smoking outside their homes or away from their children. Fifteen (37%; 95%CI: 23-53) of the children had urinary cotinine levels ≥1 ng/ml, of which seven (17%; 95%CI: 8-32) had levels ≥5 ng/ml. FEV1 and FEV0.5 were lower in subjects with a urinary cotinine level ≥5 ng/ml as compared to those with levels <1 ng/ml or between 1 and 5 ng/ml; both at baseline and after inhalation of albuterol. Five of seven subjects with urinary cotinine levels ≥5 ng/ml had FEV0.5 less than 65% of predicted values. There were no significant differences in IOS measures.

Conclusions: Despite parental denial of smoking near their children, preschool children may be exposed to ETS. Such low-level ETS exposure may affect lung function, possibly in a dose-dependent manner.