CFLs contain a very small amount of mercury sealed within the glass tubing – an average of 5 milligrams (roughly equivalent to the tip of a ball-point pen). Mercury is an essential, irreplaceable element in CFLs and is what allows the bulb to be an efficient light source. 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.
There is currently no substitute for mercury in CFLs; however, manufacturers have taken significant steps to reduce mercury used in their fluorescent lighting products over the past decade.
What is mercury, what are the sources of mercury emissions, and what are the risks?
Mercury is an element (Hg on the periodic table) found naturally in the environment. Mercury emissions in the air can come from both natural and man-made sources. Utility power plants (mainly coal-fired) are the primary man-made source, as mercury that naturally exists in coal is released into the air when coal is burned to make electricity. Coal-fired power generation accounts for roughly 40% of the mercury emissions in the U.S. EPA is implementing policies to reduce airborne mercury emissions. Under regulations issued in 2005, coal-fired power plants will need to reduce their emissions by 70 percent by 2018.
CFLs present an opportunity to prevent mercury emissions from entering the environment because they help to reduce emissions from coal-fired power plants. A coal-fired power plant will emit 13.6 milligrams of mercury to produce electricity required to use an incandescent light bulb, compared to 3.3 milligrams for a CFL.
Even in areas without significant coal-fired power generation as part of the electricity mix (e.g., Alaska and the Pacific Northwest), there are other, equally positive environmental impacts from saving energy through the use of CFLs: reduction of nitrogen oxides (which cause smog), and prevention of substantial quantities of CO2, a greenhouse gas (which is linked to global warming), as well as other air pollutants.
Airborne mercury poses a very low risk of exposure. However, when mercury emissions deposit into lakes and oceans, they can transform into methyl mercury that builds up in fish. Fish consumption is the most common pathway for human exposure to mercury. Pregnant women and young children are most vulnerable to the effects of this type of mercury exposure. The Food and Drug Administration (FDA) estimates that most people are not exposed to harmful levels of mercury through fish consumption. However, the FDA and state agencies do issue public health advisories.
EPA offers additional information and resources on all sources of mercury at www.epa.gov/mercury.