The Disadvantages of CFL Lighting
- The quality of light from a CFL varies with temperature, and the lower the temperature, the more the light resembles that from an incandescent bulb. If the temperature is too high, the light can be harsh even though it is brighter. Moreover, the gas excitation that produces light often flickers at the same frequency as the electricity. This "strobe effect" is more noticeable in tubular fluorescent bulbs than in CFLs, but in some CFLs, especially brighter ones, the effect can be enough to adversely affect sensitive people. Finally, the energized gas in CFLs emits ultraviolet radiation. While not a health risk, it can degrade photographic materials, fabrics and furniture finishes over time.
- Each CFL contains an average of 4 mg of mercury, a neurotoxin, according the U.S. Environmental Protection Agency (EPA). This is much more mercury than is present in an incandescent bulb and requires special procedures for disposal and cleanup if the bulb breaks. Most states and municipalities do not permit the disposal of CFLs in regular trash. The EPA is developing recycling options in conjunction with CFL manufacturers and retailers and recommends you contact your local waste agency for disposal guidelines. The EPA also outlines specific procedures to follow if a bulb breaks.
- Because of the excitation process that produces light, most CFLs need operate only after a threshold voltage has been attained, which means that they will not work with dimmer switches. Some companies do manufacture dimmable CFLs, but they won't dim as low as incandescent bulbs and are much more expensive. Although you can use a conventional dimmer switch with these CFLs, the Washington State University Energy Program recommends that you install a ballast or specially designed dimmer switch. Either of these is much more expensive than a conventional dimmer switch.
- Compact fluorescent bulbs have to reach a threshold temperature for the gas to begin emitting light, and many won't work in cold temperatures. Instead of producing a steady stream of light, they will flicker or exhibit rings of light and dark areas. This effect mitigates against using CFLs outdoors unless you purchase bulbs specially designed for outdoor use or enclose the bulb in a climate-proof fixture. If part of the bulb is colder than the rest, the colder part may exhibit a gray patch caused by mercury buildup on the glass.