Nasal passages are the airways located inside the nose that allow air to enter and exit the respiratory system. They are lined with a mucous membrane that helps filter, warm, and humidify the air we breathe. The nasal passages also contain tiny hair-like structures called cilia, which help trap dust and other particles, preventing them from reaching the lungs. These passages play a crucial role in our sense of smell, as they lead to the olfactory receptors located at the top of the nasal cavity. When we inhale, odor molecules travel through the nasal passages, stimulating these receptors and allowing us to detect different scents.