We use essential oils in our fragrance oil. This gives the most natural fragrance for a quality scent that much more enjoyable than the synthetic chemically created scents in other products. The reed diffusers also include evaporants including glycerol, BHT (butylated hydroxytoluene commonly used as an antioxidant food additive or to prevent oxidation in liquids), dipropylene glycol (commonly used in perfumes, skin care, hair care products and fog machines) and mmb (3-methoxy-3-methyl-1-butanol a biodegradable formulate).