It may be sold in some health food stores, but be wary of burning incense sticks inside your home. Recent studies have shown that burning incense can be just as harmful to your health as smoking cigarettes. Of the 64 toxins identified in incense sticks, two of them have been found to be "highly toxic," according to the journal Environmental Chemistry Letters. Since incense sticks are unregulated, there's no way of really knowing what's in that package when you buy them. If you want to scent your home, consider all-natural methods like essential oil-based sprays or simply opening a window.