Objective: To assess the impact of latent tuberculosis infection (LTBI) on pulmonary function, focusing on reductions in FEV1, FVC, and PEF, and identifying factors influencing this decline. Methodology: A cohort of 50 participants aged under 18, with confirmed LTBI via tuberculin skin tests or interferon-gamma release assays (IGRA), was enrolled in the study. Exclusion criteria included individuals with active tuberculosis, pre-existing pulmonary conditions, and those undergoing immunosuppressive therapy. Participants underwent baseline pulmonary function tests, including spirometry, and were followed for 24 months with regular assessments of pulmonary function, clinical status, and lifestyle factors. Data were analysed using descriptive statistics, repeated-measures analysis, multivariate regression, Kaplan-Meier survival analysis, and Cox proportional hazards models. Results: The study revealed a gradual decline in pulmonary function over time. The mean FEV1 decreased from 85.2% to 80.3% over the 24 months. Similarly, FVC and PEF also showed reductions. Multivariate regression analysis identified age, smoking history, and severity of LTBI as significant predictors of pulmonary decline, with severe LTBI having the most pronounced effect. Kaplan-Meier survival analysis showed that participants with severe LTBI developed active tuberculosis more rapidly, with a median time of 12.2 months compared to 18.4 months in those with mild LTBI. Cox proportional hazards models confirmed that older age, smoking history, and severe LTBI were associated with an increased risk of pulmonary decline. Conclusion: LTBI is associated with a gradual and significant decline in pulmonary function over time, with severe LTBI and smoking history being key risk factors. The study emphasizes the importance of early detection and monitoring of LTBI to prevent long-term respiratory complications and progression to active tuberculosis. Further research is needed to explore interventions to mitigate pulmonary impairment in LTBI patients.