Background: 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 mere 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.         Objective: This study aims to explore the relationship between exposure to environmental tobacco smoke and the severity of clinical manifestations, laboratory findings, and hospitalization duration in infants with community acquired LRTIs.         Methods: A cohort of 115 infants aged 1-24 months, hospitalized due to community acquired LRTIs and without prematurity or chronic diseases, was evaluated. We collected and analyzed data on household tobacco use and measured infant cotinine levels, a biomarker for tobacco exposure, to assess the impact of ETS on the severity of LRTIs.         Results: Findings revealed a significant correlation between higher household tobacco use and increased infant cotinine levels (p=0.001), although the proximity of tobacco consumption to the child did not significantly affect cotinine levels (p=0.501). Notably, elevated cotinine levels were significantly associated with lower oxygen saturation at admission (p=0.038), indicating a direct link between tobacco exposure and the severity of respiratory distress in infants. The study highlights the critical importance of maintaining tobacco-free environments for infants, demonstrating the adverse effects of secondhand, but also thirdhand ‘surface’ smoke exposure on infant respiratory health.