Mercury is an essential component of many energy-efficient light bulbs. The two most common types of energy-efficient lighting that contain mercury are: 

•  fluorescent bulbs, including compact fluorescent light bulbs (CFLs) and 
•  high intensity discharge (HID) bulbs. 

Fluorescent bulbs provide lighting to most schools, hospitals, office buildings and stores.  HID bulbs include mercury vapor bulbs, metal halide and high-pressure sodium bulbs, and are used for streetlights, floodlights, parking lots, and industrial lighting.  Other mercury-containing bulbs include neon/argon lamps commonly used in the electric sign industry.  

Although lighting manufacturers have greatly reduced the amount of mercury used in lighting over the past 20 years, they are not yet able to completely eliminate the need for mercury.  While mercury-containing bulbs contain small amounts of mercury (an average of 5 milligrams or about 1/100th of the amount of mercury found in a mercury fever thermometer), they are one of numerous sources that collectively impact the environment during disposal.  

Nationwide, over 670 million mercury-containing bulbs are discarded each year.  Most of these bulbs are still discarded with municipal solid waste that is ultimately landfilled or incinerated.   These disposal methods can lead to a release of elemental mercury into the environment through breakage and leakage and ultimately contaminate the food chain.  These bulbs should, therefore, be recycled after they burn out. Virtually all components of a fluorescent bulb can be recycled. The metal end caps, glass tubing, mercury and phosphor powder can all be separated and reused. Recyclers often sell the metallic portions as scrap metal. The recycled glass can be remanufactured into other glass products. The mercury can be recycled into new fluorescent light bulbs and other mercury-containing devices.

Fluorescent bulbs that are discarded in the trash will break and some mercury will be released into the environment. However, the use of mercury-containing bulbs for general indoor lighting makes good environmental sense.  These bulbs are significantly more energy-efficient than incandescent bulbs because they require less energy to provide lighting.  Electrical generation from coal-burning power plants also releases mercury into the environment.  The use of fluorescent bulbs in place of incandescent bulbs lowers energy use and thus reduces the associated release of mercury from many power plants.  Fluorescent bulbs are also more cost effective because they last up to 10 times longer than incandescent bulbs.  EPA strongly encourages the recycling of all mercury-containing bulbs after they burn out.