Compact fluorescent light bulbs (CFLs) use 75 percent less electricity than incandescent light bulbs for the same amount of light. (For why, see Bill's post "Why Switch to Compact Fluorescents".) But some people fear CFLs because of the tiny amount of mercury they contain. The risk from a broken CFL is extremely small, but CFLs should be disposed of properly so landfills aren't polluted. Sealing used bulbs in plastic bags before placing them in the trash can slow the release of mercury if the bulb breaks. But recycling is ideal.

The problem, until now, has been that recycling CFLs was inconvenient for post people. That's about to change, thanks to Home Depot. The New York Times reported this week that Home Depot will offer CFL recycling at all of its nearly 2000 U.S. stores. That puts 75 percent of Americans within 10 miles of a CFL recycling location.

If you're not part of that 75 percent, you still have options. Ikea stores provide CFL recycling bins, as well. Or visit Earth 911 or Lamp Recycle to look for a recycling location near you.

Need help choosing the right CFL? Visit our online guide, "How to Pick a Better Bulb".

On February 3, Parade published a misleading Medical Alert column with the headline "Bright Lights, Bad Headache?" by Dr. Isadore Rosenfeld. It starts with a list of unsubstantiated claims:

As energy-saving fluorescent lightbulbs become standard, new research suggests some dangers: Flickering bulbs have been reported to precipitate migraines or even seizures, though manufacturers say the new models have been improved. Fluorescent light also can aggravate skin rashes in people with lupus, eczema, dermatitis or porphyria.

Environmental Defense could find no published scientific studies demonstrating that compact fluorescent light bulbs (CFLs) trigger migraines or seizures. And unlike older fluorescent tube lights, modern CFLs with electronic ballasts don’t flicker.

Rosenfeld's statement about fluorescent light harming people also is highly misleading. While there is a theoretical risk to people with severe photosensitive skin diseases from the small amount of ultraviolet light emitted by CFLs, most people with eczema – a very common disease – have no such photosensitivity. People who are unable to tolerate any sunlight due to photosensitivity may be advised to avoid additional exposure to the small amount of ultraviolet light from CFLs, but this is only a subset of people with eczema and lupus.

The piece then mentions that CFLs contain mercury. This is true, but the amount of mercury in a typical CFL is very small, only 4 to 5 milligrams, and newer bulbs have even less. This is almost one thousand times less than what used to be in mercury thermometers. While people certainly should avoid exposing themselves to the mercury from a CFL if it breaks (see my previous post for how to properly dispose of CFLs), the exposure from a single broken bulb is comparable to the mercury in a few cans of tuna, and would not be expected to cause ill effects.

Articles like "Bright Lights, Bad Headache?" that make serious claims of harm from CFLs need to substantiate those claims with solid science. Why? Because CFLs have the potential to dramatically reduce energy use, and coal-generated electricity releases much more mercury (and other toxic pollution) than CFLs.

Parade does a disservice to its readers and the environment by propagating inaccuracies, half-truths and misleading statements. Instead of a medical alert, it should be issuing a junk science alert and tracking down the facts.

Yesterday, the New York Times ran a story about light bulbs. If you only read the beginning of the article, you might think it was saying that compact fluorescent lights (CFLs) have poor quality light. But in fact, its conclusion – after testing a wide array of bulbs – was that some are better than others.

It's true – some are better than others. For information on CFLs and how they differ, check out our online guide, How to Pick a Better Bulb.

One reason that old-fashioned incandescent light bulbs are such a particularly poor idea in summer is that they put out a lot of heat compared to compact fluorescent light bulbs (CFLs). If you're air conditioning your home, incandescent lights will require your air conditioner to work harder because you're basically heating and cooling the room at the same time.

Some people have translated this into the advice that incandescent light bulbs are good in winter because they supplement the heat to your home, making up for the additional energy they draw. I asked James Wang, Ph.D., a climate scientist at Environmental Defense, to calculate whether this was indeed true. His answer was no. Here's why.

A light bulb – whether incandescent or compact fluorescent – is essentially an electric space heater. This is true even though a portion of the bulb's output is visible light, since the light eventually dissipates to heat. CFLs produce less heat than incandescent bulbs because they use less power to produce a given amount of visible light.

Since a light bulb is essentially a space heater, its CO₂ emissions are comparable to that of an electric heating system. By comparing the CO₂ emissions from home heating systems that use electricity, natural gas, and heating oil, we can know whether supplementing heat with incandescent light bulbs is a good idea.

Electricity can come from many sources, some dirtier than others. The national average for electricity generation is 1.34 lbs. of CO₂/kWh (kilowatt hour). One kWh equals 3413 BTUs (British Thermal Units), so that's 393 lbs. of CO₂/million BTUs. About 7 percent of energy is lost during the transmission of electricity from power plants to homes, and for electric space heaters, the efficiency of conversion to heat is 97-99 percent. So total emissions are 424 to 433 lbs. of CO₂/million BTUs, given the usual mix of electricity sources in this country. If all electricity were produced from renewable energy, emissions would be close to zero, but that's not the case.

Natural gas emits 117 lbs. of CO₂/million BTUs. The efficiency of natural gas home heating systems is 78 to 97 percent, so total emissions are 121 to 150 lbs. of CO₂/million BTUs. (This omits the small amount of methane that leaks out of natural gas distribution systems.)

Heating oil emits 161 lbs. of CO₂/million BTUs. The efficiency of oil home heating systems is 80 to 89 percent, so total emissions are 181 to 201 lbs. of CO₂/million BTUs.

As you can see, electric heat (light bulbs) is the most CO₂- intensive heat source. The inefficiency stems mostly from the energy wasted in converting fossil fuel energy into electricity and then to heat, versus converting fossil fuel directly into heat.

So the next time someone tells you that incandescent light bulbs are okay for winter use, set him straight!

Compact fluorescent light bulbs (CFLs) use dramatically less energy than incandescent bulbs and reduce greenhouse gas emissions. But they also contain mercury – a dangerous toxin.

What if you drop a CFL and it breaks? How much trouble are you in?

Despite some alarming news reports, you don't have much to worry about. If a CFL breaks, some of the mercury that's contained in the bulb will evaporate into the air. How much? It's hard to be certain, but one study [PDF] looking at long tubular fluorescent bulbs found that over a two week period, only 17 to 40 percent of the mercury in the bulb evaporated. The rest remained stuck in the bulb. Roughly one-third of the mercury that evaporated did so in the first eight hours after the breakage; the rest seeped out slowly over the remainder of the study period.

The amount of mercury in a CFL is very small, only 4-5 milligrams. This is almost one thousand times less than what was in mercury thermometers! So, let's assume that what happens with CFLs is comparable to what happens with tubular fluorescents. If a bulb breaks, only 0.67 milligrams of mercury (one-third of 40 percent of 5 milligrams) might become airborne in the room during the first eight hours, and only a fraction of that would be breathed in. In short, the exposure from breaking a compact fluorescent bulb is in about the same range as the exposure from eating a can or two of tuna fish. (See our list of "Best and Worst Seafood Choices" for more on mercury in fish.)

The tiny amount of mercury you're exposed to when breaking a CFL is extremely unlikely to cause any ill effects, noticeable or otherwise. But how do you minimize even this tiny amount of risk?

Remove children and pets from the room, and then clean up the broken bulb as quickly as possible. First, increase the ventilation in the room where the bulb broke by opening windows and doors. Then use index cards or other stiff paper to pick up the broken pieces of glass and any visible mercury. Don't use your bare hands, and don't use a vacuum cleaner because this can disperse the mercury more widely. Once you've gotten up the big pieces, use something sticky like duct tape to get up smaller pieces and dust. To be extra safe, stay out of the area for a few hours to let any remaining mercury disperse.

So what does mercury poisoning do to you, anyway? The symptoms are primarily neurological. A low level exposure (like if you broke a dozen CFLs in your house every day for a couple of weeks) would cause insidious symptoms – fatigue, memory problems, difficulty concentrating, and perhaps some mild clumsiness. Higher exposures could give tremors, and mood or emotional disturbances. But this is never going to happen from dropping one CFL!

Because they contain mercury, it's best to recycle CFLs (Earth911.org can tell you how), or bring them to your local Household Hazardous Waste (HHW) collection site. I've got five bulbs wrapped in bubble wrap in my basement, waiting for me to get a chance to take them to the county HHW site. But if you can't do that, you should seal used bulbs in a plastic bag before placing them in your regular trash.

And if despite your best efforts the bulbs end up breaking in a landfill, using CFLs should still cause a net decrease in mercury in the environment. Why? Because they so dramatically reduce energy use, and coal-generated electricity releases much more mercury than a CFL ever could.

The phrase "contains mercury" sounds alarming, but there is very little risk in the tiny amount of mercury in CFLs, and the benefit to the environment of using them is huge. To learn more about switching to CFLs, visit our guide to making the switch.

Ever stop to wonder why, since the mid-1990's, traffic lights don't seem to burn out? They can't be using old-fashioned incandescent bulbs – those burn out all the time. Maybe they switched to longer-lasting compact fluorescent lights (CFLs)? Nope. Today's stop lights use light-emitting diodes (LEDs).

LEDs last 35,000 to 50,000 hours – five times longer than the average CFL, and 50 times longer than an incandescent bulb. In fact, because the technology is so different, they don't really ever burn out. They just get dimmer over time – a long time. Today's LEDs produce more light per watt than conventional bulbs but they're not quite as efficient as CFLs… yet. On the plus side, unlike CFLs they contain no mercury whatsoever.

You can find LEDs in all kinds of places – flashlights, television remotes, car headlights, flat screen displays, exit signs and even holiday lights, just to name a few. So, thinking of buying some LED light bulbs?

You can, if price and selection are no object. Though LEDs have been used in niche applications for a decade, the technology is still evolving for general-purpose light bulbs. The Lighting Science Group is about to release a 15W equivalent globe bulb [PDF] that will screw into a standard socket, but it will cost $50. Other LED lamps are slowly coming to light, too, including Lucesco's Halley light, a winner from 2006's Lighting for Tomorrow LED competition.

Obviously, prices need to come down, and for that reason, mass-market LED light bulbs are still 5 to 10 years away. And because their light is so directional, it remains to be seen whether they'll be able light up a room like incandescent bulbs and CFLs. But many scientists and lighting experts hold out hope that LEDs are the future of lighting.

In the meantime, by all means switch to CFLs. Our guide can help you find ones to fit in different places and give off different kinds of light. By the time they burn out, LED light bulbs should be available – and more affordable.

Last year, in converting my apartment to energy-saving compact fluorescent lights (CFLs), I broke two. I opened the window, swept up the fragments, wiped the floor with a damp paper towel, put the towel and the broken CFLs in a plastic bag and tied it. My super disposed of the bag. I'm not worried about mercury exposure – they broke a couple of months ago, and my cats and I are fine. A similar incident in Maine was a different story.

When Brandy Bridges shattered a CFL spiral in her daughter's bedroom, aware that it contained trace amounts of mercury, the concerned mother looked into proper disposal. After a mishmash of good and bad advice, she ended up with a $2,000 clean-up bill and a lot of fear (read full story).

What can we learn from Ms. Bridges? Know some basic facts.

Even though CFLs contain some mercury, they actually reduce overall mercury pollution. How? CFLs require less energy to be generated by power plants, which tend to emit mercury. A CFL eliminates three-fourths of the mercury pollution of a traditional light bulb: 3.3 mg versus 13.6 mg. So using CFLs slashes the amount of mercury we put into our air and surface water. That means less of the toxin ends up in our drinking water and fish.

When disposed of properly, the trace amount of mercury in the bulbs does not threaten the environment. The average CFL contains 4 to 5 mg of mercury – a smidgen compared to other everyday items such as thermometers (500 mg), older thermostats (3,000 mg), and typical office lights (40 mg).

Should a bulb break, take these simple precautions. If a CFL breaks, first open nearby windows to disperse any vapor that may escape. Then sweep it up instead of vacuuming it to minimize vaporizing the mercury (that's when it becomes toxic). Do not use your hands. Finally, wipe the area with a damp, disposable paper towel to pick up all glass fragments. Place all fragments in a sealed plastic bag and call 1-800-CLEAN-UP or go to earth911.org to find out where to dispose of it.

When a CFL burns out, years down the road, recycle it. Recycling options for CFLs are becoming more common; call your local government or visit earth911.org to see if there's a drop-off point nearby. As we switch to energy-saving lights, we also need to encourage our communities to provide local recycling facilities. In the meantime, consider buying from stores that already recycle, such as Ikea.

For more information on CFLs and proper disposal, please see the following fact sheets:

• Energy Star – Frequently Asked Questions [PDF]
• U.S. Department of Environmental Protection Fact Sheet [PDF]

When incandescent light bulbs were first invented, they were a technological marvel. Today they are a technological dinosaur. They work by heating a filament until it glows, and as a result are more akin to heaters that give out a little light, than light sources that give out a little heat. And all that heat is wasted energy.

CFLs don’t use a hot filament, so they require a lot less electricity. A 15-19 watt CFL will produce the same amount of light as a 60 watt incandescent. That’s a 75% savings on your electric bill, and a 75% cut in global warming pollution*. Using CFLs means saving money, as well as helping to save the planet.

Ok you say, but how much of a difference can using a CFL really make? A lot more than you might think! If every American household replaced just one 60-watt incandescent bulb with a 15-watt CFL, it would reduce greenhouse gas emissions as much as taking a million cars off the road!

Another comment I often hear is, "CFLs will make my home look like a warehouse." That may have been true in 1980 when CFLs were first released, but they've come a long way. Today the light from many CFLs is indistinguishable from the light we're used to. Extra small CFLs can fit in light fixtures that standard ones cannot, and you can buy 3-way and dimmable CFLs.

Another issue is mercury pollution. CFLs contain tiny amounts of mercury – about 4-5mg – and so need to be disposed of properly. (See information on CFL disposal.) But even so, CFLs are a better choice than incandescents. This is because so much of our electricity comes from burning coal, which releases large amounts of mercury into the atmosphere. Since CFLs use so much less energy, they causes less mercury pollution than incandescent lightbulbs.

If you’re convinced and want to go out and get some CFLs, first take a few minutes to learn what's available. There are a lot of CFLs out there. Some may be suitable for your needs, and others not. The most frequent mistake folks make is buying the wrong CFL and then deciding that CFLs are not for them.

My advice is to first visit our comprehensive guide to CFLs to find which CFL is right for you. Another site with great information is http://www.18seconds.org/ (18 seconds being the time it takes to change a light bulb).