Mercury is an essential ingredient in all energy efficient lighting technologies, including compact fluorescent bulbs. A typical fluorescent lamp is composed of a phosphor coated glass tube with electrodes located at either end. The tube contains mercury, of which only a very small amount is initially in vapor form. When a voltage is applied, the gas is heated-vaporizing the mercury. The electrodes then energize the mercury vapor, causing it to emit ultraviolet (UV) energy. The phosphor coating absorbs the UV energy, causing the phosphor to fluoresce and emit visible light. Without the mercury vapor to produce UV energy, there would be no light.
The following table shows the range and average mercury content in different types of lamps and bulbs. Fluorescent lamps represent about 80% of total mercury content in the lighting marketplace. Average mercury content in fluorescent lamps has decreased from about 38 milligrams in 1990 to 14 milligrams today. By comparison, older home thermometers contain 500 milligrams of mercury and many manual thermostats contain up to 3000 milligrams. It would take between 100 and 600 CFLs to equal those amounts.
|Milligrams of Mercury in Lighting Products|
¹ Source: High-Intensity Discharge Lamps Analysis of Potential Energy Savings (EERE, December 2004)
There are currently no commercially available fluorescent lamps that do not contain mercury. According to the National Electrical Manufacturing Association, “it is unlikely that an energy efficient mercury-free fluorescent lamp will be commercially available in the near future. The lamp industry and the research community have not found a substitute that has mercury’s unique energy efficient properties. Research shows that a fluorescent lamp made without mercury would consume approximately three times more energy than a mercury-containing lamp to produce the same light output.”
One possible alternative is so-called “low mercury” fluorescent lamps. See the links below or call the listed phone numbers for more information.