Foreign matter is normally expelled from the human respiratory system by a lining of very fine hairs, called cilia. Firstly, the hairs are coated with mucus that captures any germs and particles in the air we breathe before it enters the lungs. The cilia beat in a wave-like motion which brushes foreign matter upwards into the pharynx. The foreign matter is then expelled from the body through swallowing, coughing or sneezing.