What would happen if the respiratory system did not have mucus or cilia?

Without mucus or cilia in the respiratory system, the airways would be much less effective at trapping and clearing out dust, pathogens, and other particles. This would lead to a higher risk of respiratory infections and inflammation, as harmful substances could easily reach the lungs. Additionally, the lack of these protective mechanisms could result in impaired gas exchange, reducing overall respiratory efficiency and compromising oxygen delivery to the body.