Secondhand Smoke Exposure and Its Impact on Pediatric Lung Function, Aerobic Fitness, and Body Mass: Evidence from a Cross-Sectional Study

Background: Several studies have documented the detrimental impacts of secondhand smoke (SHS) exposure to a range of pediatric respiratory conditions, including asthma, bronchitis, and reduced lung function. The aim of the study was to investigate the influence of SHS exposure on lung function, physical fitness, and body mass index (BMI) in children aged 10 to 14 years. Methods: This cross-sectional study included children aged 10 to 14 years at the Elementary School "Trilj" in Trilj, Croatia. Data on SHS exposure were collected using a questionnaire. Antropometric and spirometry measurements were performed. Physical fitness was assessed using the shuttle run (BEEP) test. Results: This study included 157 children, 89 (56.69%) boys and 68 (43.31%) girls. Children exposed to every day SHS in households had significantly lower values of forced vital capacity (FVC), forced expiratory volume in one second (FEV1), FEV1/FVC, peak expiratory flow (PEF) (p < 0.001) and higher z-score BMI levels (p = 0.018) in comparison to unexposed children. Logistic regression showed that children unexposed to SHS had higher odds for better results in the BEEP test (OR 62.45, 95% CI 21.26-179.24, p < 0.001). Children with poorer physical fitness, expressed by lower BEEP score levels, had significantly lower FVC, FEV1, FEV1/FVC, and PEF (p < 0.001). Conclusions: Every day SHS exposure in children was associated with poorer lung function, higher BMI, and poorer physical fitness.