Incense is an aromatic biotic material that releases fragrant smoke when burnt. It is used for aesthetic reasons, religious worship, aromatherapy, meditation, and ceremony. Incense is composed of aromatic plant materials, often combined with essential oils. The forms taken by incense differ with the underlying culture, and have changed with advances in technology and increasing number of uses. Incense can generally be separated into two main types: "indirect-burning" and "direct-burning".
- Indirect-burning incense: This type of incense is not capable of burning on its own, and requires a separate heat source.
- Direct-burning incense: This type of incense is lit directly by a flame and then fanned or blown out, leaving a glowing ember that smoulders and releases a smoky fragrance.
Incense has been used since ancient times in religious rituals in ancient Egypt, Babylon, and Greece. Burning incense has a long religious and spiritual history and remains an important ritual for many. It is also used in aromatherapy or to simply create a pleasing aroma in the home. Incense is also known to have some health benefits. However, incense smoke contains particulate matter, gas products, and many organic compounds, which can have clinical, structural, and molecular effects on airway disease.
