Brendan Koerner tells us why in Slate.
But what about the mercury? The toxic heavy metal is integral to the design of current CFL bulbs: Electricity agitates the mercury molecules, causing them to emit ultraviolet light. That light then spurs a bulb's phosphor coating to give off visible light. But the amount contained in each bulb is barely enough to cover the tip of a ballpoint pen, and won't cause any bodily harm as long as simple precautions are taken. The National Electrical Manufacturers Association has voluntarily imposed a limit of 5 milligrams per bulb on all CFLs sold in the United States—about 1 percent of the mercury contained in an old home thermometer. Since manufacturers are well aware that health fears are preventing the widespread adoption of CFLs, most have committed to making bulbs with even less mercury than NEMA's standard. The average CFL bulb now contains around 4 milligrams of mercury, and that figure should drop closer to 2 milligrams in the very near future. Much of the credit for these reductions goes to Wal-Mart, which has pressured GE, Royal Phillips, and Osram Sylvania to cut down on the quicksilver.
I'm glad they're working on the mercury problem. Now about the quality of the light from CFLs, it is my opinion that it varies not only across the brands, but also across bulbs of the same type and style from the same brand. I've been gradually replacing most of our incandescents as they burn out. For the most part, they're ok. I do like the fact that you get more lumens per watt. In the right kind of fixture, like a sconce where the lighting is indirect, I don't notice any real light quality issue. For direct lighting, they do take some getting used to.
Anyway, I'll use them until they figure out how to make LED lights that aren't blue. I keep hearing how LED lights are the next great thing and that they will solve all of the problems people have with CFLs. LEDs will last virtually forever. They are dimmable. They can be made to change color.
They just can't change them to a color that approximates light from incandescent light bulbs. I have a couple of LED flashlights. They are a very annoying shade of blue. Solve that problem, and our lighting issues are history.
I'm waiting.
The LEDs are getting better, but they still have a long way to go - very much not yet ready for the mass consumer market in my view. CFLs are much further along.
For LEDs, see: http://tinyurl.com/3cc59v
and for the latest in CFLs, see: http://tinyurl.com/2r4l7e
Both links are for product reviews at the aptly named Treehugger!
Sorry about the delay getting the comment up. I have it set to moderate when there is more than one link.
William, there is much variation in the "warmth" spectrum of current LEDs for area lighting. When it comes to LEDs flashlights though, you shouldn't be having any trouble at all...unless you are constrained to spending <$20 on a light. Surefire, Peak LED Solutions, and several other US-made lights are pure white (or in the case of Peak, you can specify whatever "temperature" of color you'd rather have). Moving to Chinese-made lights, you can't go wrong with Fenix. I have 4 of these, and the light is brilliant white, very bright, and the quality if very high. One of those Fenix lights has a CREE LED (US made in N.C.) and is a face melter.
You piqued my one of my several interests. I have an Orb light from the UK that is shorter than a ChapStick and brighter than a 2-D cell Maglite. Amazing stuff is happening with LEDs these days.
Well, I'm willing to pay for a good light, but I haven't made the investment of shopping for a really good one in a world where there is still a lot of variation in quality.
Plus, what I read about LED lights is that--your comments notwithstanding--they're not quite ready for prime time.
From what I understand, even some of the better lights have a peak at one part of the spectrum rather than having the broader spectrum we associate with other sources of light.
Even the ones I have seen that look more white than others still have an odd quality to them. I could get used to it, and for some applications, I probably wouldn't mind at all.
I'm fully confident that these issues will be solved, and perhaps soon. I look forward to the day that I can go to my local big box store and get an LED light that I can really appreciate. That day is near, I have no doubt.
But in the meantime, I might check out some of the ones you mention and see if they are as good as you claim.