This study investigates the long-term effects of COVID-19 on lung function and Peak Expiratory Flow Rate (PEFR) in smokers versus non-smokers. COVID-19, known to affect the respiratory system severely, has led to persistent pulmonary complications, including fibrosis and reduced lung function. Smokers are already at increased risk due to pre-existing lung damage, making it essential to understand their post-COVID recovery. The study aims to assess and compare lung function using spirometry (FEV1, FVC) and PEFR in individuals aged 18–50 who recovered from COVID-19 at least one year ago. By comparing smokers and non-smokers, it will help identify whether smoking exacerbates long-term pulmonary impairment after COVID-19. The study uses a cross-sectional observational design with a sample size of 100, applying simple random sampling. It aims to provide evidence to support smoking cessation and tailored pulmonary rehabilitation strategies. The novelty lies in its focus on long-term post-COVID lung changes in a healthy, working-age population—an area not well studied. Findings are expected to benefit clinical practice, guide public health interventions, and inform patient education by emphasizing the importance of smoking cessation in improving lung recovery and reducing the risk of long COVID-related respiratory dysfunction.