Why Is There Mercury in Lightbulbs?

Fluorescent lightbulbs contain small amounts of mercury inside, which helps facilitate the process of creating light within the bulbs. A few types of fluorescent lightbulbs may contain a small amount of mercury and mercury vapor. Mercury can also be a potential neurotoxin, and the presence of this toxin in lightbulbs can pose a risk in certain situations.

Types

• There are many types and sizes of fluorescent lightbulbs. Common types include the traditional long fluorescent tubes that connect to light fixtures called ballasts. These are the types seen commonly in office buildings. Compact fluorescent bulbs (also known as CFLS) are small bulbs designed for home and small lighting uses. They come in a variety of shapes such as the U-shape, circular and spiral shape. Some visual examples are available in the Resources section of this article.

Function

• Mercury within these lightbulbs aids in light production. When electricity is applied to the electrodes in the lightbulb, the mercury vapor inside the glass tubing becomes energized. The result of this energy is ultraviolet (UV) light produced from the mercury.

  The inside of the glass tubing is coated with phosphor, which absorbs the UV light. This absorption causes a reaction that results in visible light being emitted by the coating.

Amount of Mercury Present

• The amount of mercury present in a lightbulb is generally small and measured in milligrams. The amount in a bulb may vary based on the size of the bulb and the manufacturer of the bulb. Fluorescent lights and CFLs tend to last a lot longer than traditional lightbulbs, and mercury levels may be slightly higher in large bulbs designed to last the longest. CFLs, for example, can last up to 10,000 hours.

Warning

• Normal handling and usage of mercury-containing bulbs is relatively safe. The problem is that when one of these bulbs is broken, the mercury and mercury vapor can leak out and exposure must be avoided.

  Use care when handling these bulbs and when installing them. You should dispose of these bulbs by placing them in a double-sealed plastic bag. Contact your local waste management office to see if they offer special hazardous waste disposal for these bulbs.

  If a mercury-containing bulb breaks in your home or office, open windows to clear out the vapors. Dispose of any clothing or bedding that comes into contact with the broken glass, and do not use a vacuum to pick up debris. Use duct tape to lift debris off the floor. Do not directly touch the pieces of glass.

Considerations

• In addition to CFLs and other fluorescent bulbs, some high-intensity discharge (HID) lamps also contain mercury and mercury vapors. However, these lightbulbs are often found in industrial and large-scale uses such as in street lamps and are rarely found in the home or office setting.