Objective: The present study was performed to determine the relationship between environmental tobacco smoke (ETS) exposure and acute lower respiratory tract infection (LRI) caused by respiratory syncytial virus (RSV) in children.

Material and Method: The authors did the study in 71 children (median age 12 months; 60% male) who were admitted to King Chulalongkorn Memorial Hospital with acute LRI between June and September 2004. 27% had RSV infection.

Results: RSV-LRI required longer duration of oxygen therapy than non RSV-LRI (4.5±1.7 vs. 2.8±1.3 days; p<0.001). Desaturation in room air was more common in the former group compared to the latter group (37 vs. 11%; p = 0.01). There was no difference in urinary cotinine level between the two groups (median 0.5 vs. 0.6 mcg/mg Cr; ns). Among RSV-LRI, those with desaturation had higher urinary cotinine level than those without desaturation (median 0.8 vs. 0.0 mcg/mg Cr; p = 0.04).

Conclusion: ETS exposure was not associated with RSV-LRI but increased the risk of desaturation in these patients.

Keywords: RSV, Passive smoking, Children, Cotinine, Acute lower respiratory tract infection