Environmental Tobacco Exposure Linked to Lower Oxygen Saturation in Infants with Community-Acquired Lower Respiratory Tract Infections

Objective: Tobacco smoke is a pervasive environmental hazard, particularly detrimental to the developing respiratory systems of infants. Exposure to environmental tobacco smoke (ETS) has been consistently implicated in the etiology of a spectrum of lower respiratory tract infections (LRTIs), which are a leading cause of morbidity in children under two years of age. The pathophysiological impact of ETS extends beyond exposure; it actively exacerbates the severity of respiratory conditions, often resulting in increased hospital admissions and prolonged medical care for the youngest and most vulnerable. This study aimed to explore the relationship between exposure to ETS and the severity of clinical manifestations, laboratory findings, and hospitalization duration in infants with community-acquired LRTIs. Material and Methods: A cohort of 115 infants aged 1–24 months, hospitalized due to community-acquired LRTIs and without prematurity or chronic diseases, was evaluated. Data on household tobacco use were collected, and infant cotinine levels were measured to assess the impact of ETS on the severity of LRTIs. Results: Findings revealed that the frequency of urinary cotinine positivity is significantly higher in infants from households with smokers (p=0.001). Among patients with household smoking, the proximity of tobacco consumption to the child did not affect the frequency of cotinine positivity (p=0.501). Notably, the cotinine-positive group had significantly lower oxygen saturation at admission (p=0.038). In the RSV-positive subgroup, this association remained significant (p=0.015), providing stronger evidence that ETS independently exacerbates respiratory distress. Conclusion: This study demonstrated that tobacco exposure is associated with increased respiratory distress in infants with lower respiratory tract infections. Emphasizing the importance of smoke-free environments during infancy, it also proved the negative effects of not only secondhand smoke but also thirdhand “surface” smoke exposure on infants’ respiratory health.