Both natural and synthetic fragrances can be used in a cold air diffuser, but the choice between the two depends on your preferences: Natural Fragrances: Derived from plants, flowers, and herbs, these scents offer a pure, therapeutic experience. When used in a cold air diffuser, natural oils maintain their potency without being altered by heat. Synthetic Fragrances: These are designed to mimic scents found in nature or create entirely new aromas. They tend to have a stronger scent throw and longer-lasting fragrance. Both natural and synthetic options can be effectively used in cold air diffusers, ensuring that you enjoy consistent, long-lasting fragrance in your home.