The lighting industry has long used mercury in the production of energy-efficient lighting products.  All fluorescent lamps and almost all High Intensity Discharge (HID) lamps require a small amount of mercury to generate light efficiently. 

In fluorescent lamps, mercury efficiently generates ultra-violet radiation that is converted to visible light by the phosphor. 

Fluorescent lamps begin life with pure mercury. As the lamp operates and ages, the pure mercury is “consumed” and combines with the glass, the phosphor, the deposits on the bulb wall around the filament, and with any other impurities in the lamp.  This combined mercury becomes mercury oxide which plays no part in the production of light. 

If mercury dosing of fluorescent lamps is too low, lamp life, number of starts, color, and light output can be dramatically affected. Lamps will consume all the pure mercury before reaching rated life, requiring additional lamp replacements which increases mercury usage.

Mercury starvation in a lamp causes it to turn pink.

In metal halide lamps, mercury is used as a starting aid and to set lamp operating voltage, and high-pressure sodium lamps use mercury as a buffer gas to help set lamp operating voltage.  If mercury dosing is too low in metal halide and mercury vapor lamps, light output will be dramatically affected.

Light sources that do not use mercury, such as incandescent and halogen lamps, produce 70 to 80% less light per watt input.

There is no known substitute for mercury in energy-efficient light sources, and by using lamps that contain small amounts of mercury, we can greatly reduce the need for power generation, thereby reducing emissions from power plants -- including mercury emissions.

In the US, more than 50% of our electricity is generated by power plants that burn coal.  Mercury is a naturally occuring element in coal, and when coal is burned, the mercury is released into the air.  More than 60% of mercury in the environment comes from human activity such as coal-fired power plants, improper disposal of mercury-containing products, and medical waste incineration.

By using mercury-containing lamps and recycling them at the end of life -- even those that pass the federal TCLP test for hazardous waste, we can greatly reduce the amount of mercury that is released into the atmosphere, decreasing the potential for plant and animal exposure and human health risks.

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