It would be better if most scent diffusers used essential oils, but unfortunately, most are made with VOCs and synthetic fragrance compounds that are known or suspected to cause many health problems, like Glade plugins. Febreze and Lysol are the same but with more VOCs.

I have severe sensitivity to fragrance and cannot tolerate synthetic fragrances, incense, or essential oils. Simply being near people who use artificial deodorant, shampoo, laundry detergent, dryer sheets or any other mainstream product that leaves them covered in synthetic fragrance is very uncomfortable. Essential oils are less problematic.

With essential oils, many of the chemicals present (such as linalool and d-limonene) break down as they oxidize after diffusion, and the oxidation products have different health effects than the original chemical, such as allergy sensitization and irritation.

My mother-in-law visited for two months, and left one of the rooms in my house saturated with Young Living essential oils from a diffuser. Six months later, I still can't go in there.