Mucociliary clearance is a natural defense mechanism of the respiratory system that helps keep the airways clear of mucus, dust, and pathogens. It involves the coordinated movement of tiny hair-like structures called cilia that line the respiratory tract. These cilia beat in a rhythmic pattern, pushing mucus upward toward the throat, where it can be swallowed or expelled. Mucus traps inhaled particles and microorganisms, preventing them from reaching the lungs. This process is essential for maintaining respiratory health and preventing infections. Factors like smoking, pollution, and certain medical conditions can impair mucociliary clearance, leading to respiratory issues.