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CFLs and Mercury

5 October 2010 2 Comments

Australia, and many other countries around the world, are legislating to phase out the sale of incandescent light bulbs. It is estimated that this initiative will reduce Australia’s annual greenhouse gas emissions by 800,000 tonnes of CO2-e; not bad, but it’s still only 0.14% of our total emissions. That said, any saving is progress.

I’ve previously published about my own experience of switching from low-voltage halogen downlights to CFL downlights

In the past couple of weeks I’ve had several people express concern to me that the mercury in a CFL poses a serious health risk if it gets broken, or represents a major environmental threat. Rest assured, the mercury concern has been blown out of all proportion by people opposed to the switch.

  1. How often do you break lightbulbs?I can only think of twice in the past 10 years or so that I’ve even been near a broken bulb. If the bulb isn’t broken, no mercury is released.
  2. There’s very little mercury in each bulb.The amount of mercury contained in each globe is very small (about 3-5 milligrams), or enough to cover the tip of a ballpoint pen. A tiny watch battery contains 5 times as much mercury, and we don’t seem too concerned about carrying them around on our wrist all day. Mercury thermometers contain about 100 times that amount (500 milligrams), and again we seem happy to keep using them.
  3. Most of the mercury won’t vaporise.If a CFL bulb is broken most of the mercury remains on the glass and is not actually released into the air. Inhalation of mercury vapour is much worse than skin contact or even ingestion.
If you do happen to accidentally break a CFL globe, make sure you clean it up safely

Interestingly, the amount of coal burned to generate the additional energy used by an incandescent bulb over its lifetime would release 5 times more mercury into the environment than is contained in the CFL bulb that replaced it (source: The Environmental Engineer journal 2006). So even if the worst case happened and CFLs were dumped into landfill and not recycled, the net release of mercury into the environment would be less if we all switched.

Of course, you should dispose of old CFL bulbs properly. Contact your local Council to ask about collection programmes, or refer to the Australian federal Department of the Environment, Water, Heritage and the Arts web site.

The Australian Conservation Foundation has a pretty good explanation of this topic.

For a very thorough scientific assessment of the risks, see the European Commission’s Scientific Committee on Health And Environmental Risks’ document Opinion on Mercury in Certain Energy-Saving Light Bulbs.


  • Jessica said:

    Keep up the great work Darren. Relevant, referenced and interesting as usual. See you soon, Jess.

  • Darren (author) said:

    Thanks Jess :-).