Compact fluorescent lights (CFLs) and mercury

In December 2007, Congress passed a bill and President Bush signed it into law that would ban conventional light bulbs by 2014, starting with 100W bulbs in 2012. In February 2009 the European Union’s Environment Committee voted to phase out conventional light bulbs, starting with 100W bulbs by September 2009. Australia and Canada have similar laws, which seek to encourage consumers to switch to more energy efficient compact fluorescent lights (CFLs) that also fit conventional fixtures, but use some 75% less electricity and last up to ten times longer.

Though CFLs are more expensive to buy (from about $3 compared to conventional light bulbs at 50 cents), they will actually pay for themselves via a lower electricity bill over only a couple of months. Also, because of the much shorter life span of conventional bulbs they would be more expensive to run even if electricity were free: At 10,000 hours per CFL and 1000 hours per light bulb, you’d end up buying 10 light bulbs that cost more than the single CFL that matches their total life span.

Nevertheless, there are other criticisms brought against a switch to CFLs. One of them is the fact that CFLs, like all types of fluorescent light, contain small amounts of mercury, a toxic heavy metal. They need to be handled carefully so as not to break them. Dead bulbs must not be thrown into the trash to go into landfills or garbage incinerators. Many electrical stores or recycling centres will take them back to dispose of them safely.

However, even if most consumers dumped old CFLs into the garbage bin, it is doubtful if this would cause more environmental problems than sticking with Edison’s old invention. In many countries, cheap coal provides a major portion of electricity. In the USA it’s about half. Unfortunately coal contains trace amounts of mercury, which goes up the chimney when the coal gets burnt. This makes for some interesting numbers:

  • Annual mercury emissions from coal fired power plants in US (1999): 48 tons
  • Electricity saved in US by switching all incandescent lamps to compact flourescents: 7%
  • Equivalent mercury pollution reduction: 3.36 tons
  • Typical amount of mercury in a CFL: 4 mg
  • Number of improperly trashed CFLs per year it would take to match mercury pollution reduction from switching to CFLs: 1,000,000,000
  • Number of CFLs sold per year: 330 million

Note that mercury content in CFLs is gradually being reduced. According to a July 2008 fact sheet by Energy Star, the average mercury content in CFLs dropped at least 20% during the previous year. Some models now contain as little as 1.4-2.5 mg of mercury, driving the break-even point up to 2 to 3 billion improperly trashed CFLs per year.

Better consumer education can avoid mercury pollution, whether it’s from lamps that should not be in the garbage or from coal that should not need to be burnt due to more efficient lights.

A recent New York Times article raised some questions about failure rates of cheap CFLs. Probably the bulbs I buy are not as cheap as those mentioned in the article (I used to pay about $10 a decade ago, maybe $5 now), but in all the years that I’ve been using CFLs I have yet to experience one failing in its first year.

Here in Japan regular fluorescents (non-CFL) have been very common in homes for decades, as people here like their homes brighter than in the west, which would have used a lot more electricity and put out much more heat with incandescent bulbs.

The average Japanese dining room, kitchen, living room or bed room uses either circular or straight fluorescent lights, but CFLs have become very common where incandescent bulbs were in use before.

When I moved to my current home 9 years ago and had to buy new lamp fixtures for all the main rooms, I installed CFLs or circular fluourescents throughout. The living room and the dining room table are only on their second set of CFLs during all these years.

Most of the first generation of bulbs in those rooms didn’t actually burn out before being replaced, but merely lost some brightness (the phosphor coating gradually wears out), so I swapped them for a new set and gradually reused the old set to replace less frequently used incandescents left in the house.

CFLs are big step forward from incandescent light bulbs, but eventually we will see them replaced with solid state lights and other new technologies that at the moment are still too expensive to compete for domestic lighting.

4 thoughts on “Compact fluorescent lights (CFLs) and mercury

  1. Energy efficient light bulbs are the easiest first step consumers and businesses can take towards reducing their energy consumption. Products have gotten light years better in the past few years and, in my eyes, indisputably better for 99% of applications. Both CFL and LED light bulbs run much cooler than incandescent bulbs, use energy much more efficiently, and do offer saving on your electricity bill. I am a vendor of energy efficient bulbs, so perhaps I am a bit biased, but I don’t know why everyone doesn’t switch today.

  2. Per the World Watch Institute ( – updated today January 12, 2012, China produces 2.5 billion CFL’s (85% of the market) currently in use globally 3.5 billion – has this not exceeded the potential pollution of coal fired generating plants. One billion bulbs = 2,500,000 mercury filled thermometers in the land fill. What happened to the concern about our oceans and water resources? One bulb breaking in a child’s room on the carpet where it broke had a reading of 1,939 ng/m3 when less than 300 ng is considered acceptable (refer to; – Consumers in dark over risks of new light bulbs and They last for (supposedly 5 to 6 years) the sockets oxidize ensuring breakage when removed. The efficacy is extremely low with lamps not putting our enough lumens after six months, the room is as bright as having only the floor night lights on. A real eye strain. Please help me understand how these lamps are safer for the world and children in a home. Having a hard time understanding how this all does not seem to add up. Thank you for your help.

  3. The more CFLs produced in China and worldwide and installed in place of Edison-type light bulbs, the more power from coal-burning plants is reduced, as CFLs draw one quarter the electricity.

    These plants are a major source of mercury emissions, responsible for about 50% of mercury pollution in the US and probably even more in China, which relies overwhelmingly on coal for power.

    Consumers do need to be educated about proper cleanup procedures in case of breakage and also about proper disposal at the end of life of the bulbs. Where I live, bulbs are not collected with generic household garbage for incinerators, but separately. We properly label them before putting them out on collection day for proper handling.

    About the case in the often-quoted Canadian newspaper article: The 1,939 ng/m3 reading you mention was a local reading at one spot on the carpet, not the overall room air level after the incident. At worst the bedroom carpet needed to be replaced. The hoax-slayer article explains that the cleanup advice given in that case was not really appropriate.

    I have been using fluorescent lamps lamps virtually exclusively in my home for over a decade (the only exceptions in my previous home were some fixtures in the hall that were too small to fit CFLs and currently a pair in the bathroom mirror). I have yet to have a CFL shatter or come apart on me during all those lamp-years.

    While it’s true that CFLs become dimmer towards the end of their life, the EU standard permits no more than 25% of output loss at the end of the quoted lamp life time. After 2000 hours, they may lose no more than 12-17% of light output. By comparison, regular light bulbs burn out after about 1000 hours, i.e. they lose 100% of their light output…

    It will all become an academic issue once we switch to LED lights, which will be the next step beyond CFLs.

  4. I am agree with your explanation and facts but now when we have better options like induction lights and LED’s then why we concentrate on theCFL’s as they are much more beneficial then CFL’s

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