Fragrance lamps are devices that are used to deodorize and purify the air in a room. These lamps were widely used to help sterilize the air in hospitals but are no longer considered effective for this purpose. The main use of fragrance lamps, also referred to as catalytic lamps or effusion lamps, is to clear offensive odors from a house. They interact with some of the molecules in the air and are often filled with scented fuel which can be slowly diffused into a room.
First invented in 1897, fragrance lamps were used extensively in hospitals and mortuaries. The original manufacturers claimed that small particles of odorous molecules would react to the heat in the lamp and become neutralized. Without these particles, the room is left smelling clean. While there are some molecular reactions that occur when a fragrance lamp is used, the vast majority of odor causing molecules are not neutralized. Instead, these lamps deodorize a room by releasing a scented fuel into it.
Such a lamp has several components. A hollow bowl forms the base and is filled about halfway to the top with fuel before the lamp is lit. This fuel is made from alcohol and perfume, though unscented fuel can also be used. A wick sits in the fuel and comes out the lamp through the top, which is covered by a metal burner.
Unlike other types of lamps, fragrance lamps are not left lit. The wick is lit on the burner and then extinguished after a few minutes. Though there is no flame, the heat of the lamp continues to consume the fuel until it is completely used up. In a medium-sized fragrance lamp, this can take about an hour. It is also possible to turn off a fragrance lamp by placing a cover over the burner and removing the lamp's source of oxygen.
Without flames, fragrance lamps are able to use up their fuel at a slow and steady pace. They do not burn the fuel but infuse it into the surrounding air, producing ozone as a byproduct. Though ozone was once touted as a cleansing molecule, it can be hazardous even at low levels. Exposure to this molecule may cause breathing difficulties. The fuel in the lamp is also highly combustible and can explode into flame if the lamp is not lit correctly.