CFL Facts – The Mercury Myth

August 30, 2010 at 2:55 pm Leave a comment

CFLs are gaining in popularity as people realize that they save energy and money by using ¼ the amount of energy as a standard incandescent bulb.  But, some concerns have been raised about mercury in CFLs.  We hope to set the record straight so you can feel comfortable using CFLs and saving money!

What is a CFL?

A compact fluorescent lightbulb (CFL) is a fluorescent bulb designed to be used in a standard incandescent light bulb socket.  Because incandescent bulbs work by heating up a metal filament until it is hot, they produce mostly heat (only 2% of the energy used is converted to light).  A CFL is 4 times more efficient (8% of the energy used is converted to light), which is why a CFL using only 14 watts of electricity can produce light comparable to an incandescent bulb using 60 watts.  On average, a CFL saves $25-35 in energy costs per bulb.

What about mercury?

CFLs contain a very small amount of mercury sealed within the glass tubing – an average of 4 mg – about half the mercury found in a linear fluorescent lamp (office building lighting), and an amount that would cover the period at the end of this sentence.  Mercury is a developmental neurotoxin that can damage brain cells, so it is a chemical of concern.  Newer CFLs use about 1.4-2.5 mg.  By comparison, older mercury thermometers contain from 500 to 1,000 mg of mercury.  Mercury is an essential component of CFLs and is what allows the bulb to be an efficient light source. No mercury is released when the bulbs are intact or in use.  A coal-fired power plant will emit 8.8 mg of mercury into the air to sustain a 60-watt incandescent bulb over the time period that a typical CFL lasts (~10,000 hr), which is four times the amount of mercury released by an equivalent14-watt CFL (2.2 mg).  Even if you factor in the 4 mg of mercury in the CFL if it is put into the landfill (worst case scenario) plus the coal-fired power plant release of 2.2 mg, this is 6.2 mg released max by the CFL.  This compares to 8.8 mg of mercury released by the traditional incandescent bulb.  Also, mercury in the air is more of a health risk than mercury in the landfill.

CFLs should be disposed of properly since they contain mercury.  Burned out or broken bulbs should be brought to the local household hazardous waste site or Home Depot.

Bottom line

So should I be concerned about mercury?  Researchers at Lawrence Berkley National Laboratory liken the amount of exposure from a broken bulb to “one bite of albacore tuna.” Here is a copy of the original article.  YOU BE THE JUDGE!

More info.

The US EPA has prepared a GREAT report through its Energy Star program summarizing the mercury issue.  We highly recommend that you look at it if you have  additional concerns about mercury in CFLs.  Here is another interesting take on the mercury myth.

Entry filed under: Learn Do Teach workshops, Neighborhoods.

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