In 2001, lighting accounted for 8.8 % (101 billion kilowatt hours) of U.S. household electricity use. Incandescent lamps, which are commonly found in households, are highly inefficient sources of light because about 90% of the energy they use is lost as heat. For that reason, lighting has been one focus of efforts to increase the efficiency of household electricity consumption. Lighting manufacturers are now producing products that are significantly more energy-efficient than incandescent bulbs. Such lighting includes fluorescent bulbs. Long considered a more economical choice for commercial and industrial lighting, compact fluorescent light bulbs are becoming more attractive to household consumers. The primary difference between a compact fluorescent light bulb (CFL) and a fluorescent tube is the size. Unlike tubes, CFLs are made to fit into products that can be plugged into standard household light sockets like table lamps and ceiling fixtures. Compared to incandescent bulbs that use a heated filament to produce light, CFLs contain a gas that produces invisible ultraviolet (UV) light when the gas is excited by electricity. UV light hits a white coating inside the fluorescent bulb, which alters the light into light visible to a human eye. Because fluorescent bulbs do not use heat to create light, they are far more energy-efficient than regular incandescent bulbs. In the past, complaints about the high cost, harsh light quality, and the inability to use with a dimmer made CFLs less attractive to some consumers. However, improvements in technology have resulted in less expensive CFLs that illuminate more softly, emitting light similar to light from an incandescent bulb, that are capable of dimming. CFL sales have increased significantly in the past two years. According to the U.S. Environmental Protection Agency (EPA), 290 million Energy Star-qualified CFLs were sold in 2007. That is nearly double the number sold in 2006 (the year that CFL market share increased from a steady 5% to 11%), and represents almost 20% of the U.S. light bulb market. The primary factors contributing to the rise in popularity of CFLs are their energy efficiency and longer life. According to the Department of Energy (DOE), CFLs use about 75% less energy than standard incandescent bulbs and last up to 10 times longer. Further, according to EPA, the increase in sales is due in part to increases in consumer education and promotion by Energy Star retail partners such as Wal-Mart, Lowe's, Home Depot, Costco, Ace Hardware, and Sam's Club. Another factor that may further increase the use of CFLs is the development of energy efficiency standards for lighting. Sections 321 and 322 of the Energy Independence and Security Act of 2007 ( P.L. 110-140 , enacted December 12, 2007; referred to hereafter as the Energy Act) established energy efficiency standards for certain types of incandescent lamps, incandescent reflector lamps, and fluorescent lamps. The standards specify the maximum wattage that can be used to power lights within a range of lumens (a measure of the perceived power of light). For example, a standard North American incandescent light bulb that emits approximately 1,700 lumens uses 100 watts of power. A CFL emitting comparable lumens uses approximately 23 watts. The new standard would require incandescent lamps emitting comparable lumens to use no more than 72 watts. The deadlines for meeting the new standard fall between January 1, 2012, to January 1, 2014, depending on the range of lumens emitted by various bulbs. CFLs already meet the Energy Act's energy standard. The Energy Act has been interpreted by some as a prohibition on the sale or production of incandescent bulbs, or as a mandatory requirement to use CFLs. Neither is true. The Energy Act only establishes standards that incandescent bulbs must meet—it does not prohibit their use, nor does it mandate the use of CFLs. Mercury is a highly volatile, naturally occurring element. It conducts electricity, is liquid at room temperature, combines easily with other metals, and expands and contracts evenly with temperature change. These properties make mercury useful in a variety of household, medical, and industrial products and processes. Mercury is also a potent neurotoxin that can, at certain exposure levels, cause brain, lung, and kidney damage. Mercury is an essential component of CFLs that allows a bulb to be an efficient light source. Fluorescent bulbs, unlike many other mercury-containing consumer products, are among the few products for which non-mercury substitutes do not exist. Still, over the past 20 years, the mercury content in fluorescent tubes and bulbs has declined steadily. A CFL generally contains 2 to 6 milligrams (mg) of mercury (an amount that poses virtually no risk of harm ). By comparison, mercury has been present for decades in the following household products: watch batteries (25 mg), dental amalgams (500 mg), thermometers (500 mg to 2 grams (g)), thermostats (3 g), electrical switches and relays (3.5 g), and standard fluorescent tubes (up to 40 mg; lighting manufacturers now produce low-mercury fluorescent tubes that generally contain less than 9 mg of mercury). Increased use of CFLs has generated concern among some over the potential danger the bulbs may pose if broken in the home during use or after disposal. The amount of mercury that may be released by a CFL depends on a variety of factors, including a bulb's age at the time of disposal. As the bulb ages, the mercury content becomes bound to the glass, where it is not readily available for release into the environment unless it is burned (i.e., disposed of in an incinerator). Therefore, it is possible to essentially eliminate potential mercury releases from CFLs if they are not broken, particularly when new, or incinerated. Mercury is not released from CFLs during normal use. Consumers would be exposed to mercury only if a bulb were to break. At room temperature, some of a bulb's metallic mercury will evaporate and form mercury vapors; however, the danger posed from exposure to the amount of mercury in an individual CFL is minimal. Although the potential risk of harm associated with CFL use is relatively low, certain precautions are recommended to avoid spreading of mercury vapor. Several federal and state agencies have published cleanup and disposal recommendations for CFLs. Guidance from the different agencies varies slightly, but generally recommends the following steps: open a window and leave the room for 15 minutes, and keep pregnant women, children, and pets away from the area until it is cleaned up; gather glass fragments and powder—on hard surfaces, use stiff paper or cardboard (do not vacuum), and on carpet, pick up large pieces wearing disposable gloves; use sticky tape, such as duct tape, to pick up any remaining small glass fragments and powder; wipe the area clean with damp paper towels or disposable wet wipes; and place all waste and cleaning materials in a glass jar with a metal lid or in a sealed plastic bag, and immediately place all materials outdoors and check with local or state government about disposal requirements. In guidance provided by the Energy Star program, it has been noted that the use of CFLs in place of incandescent bulbs could actually reduce the amount of mercury emissions to the environment. Coal-fired power plants currently account for 40% of mercury emissions in the United States. During a five-year span, by some estimates, a coal-fired power plant emits 9.3 mg of mercury in the course of producing the same amount of electricity needed to power an incandescent bulb, compared to 2.3 mg of mercury emissions from a CFL over the same period. The use of CFLs in place of incandescent bulbs could also lead to comparable decreases in carbon dioxide, sulfur dioxide, and nitrogen oxide emissions—all pollutants emitted from coal-fired power plants. Any additional mercury emissions associated with CFLs could be minimized if bulbs are kept out of the waste stream (i.e., recycled rather than discarded) when spent. Products containing mercury may meet the federal regulatory definition of hazardous waste. Pursuant to the Resource Conservation and Recovery Act (RCRA), EPA has established regulations regarding the transport, treatment, storage, and disposal of hazardous wastes. However, households are essentially exempt from RCRA. This means that household hazardous waste (e.g., paint, batteries, thermostats, certain cleaning fluids, and pesticides) may be disposed of in municipal solid waste landfills or incinerators. The mercury levels in CFLs would potentially cause them to be deemed household hazardous waste. As such, EPA suggests that the bulbs not be discarded in household garbage "if better disposal options exist." EPA recommends that household consumers contact their state or local environmental regulatory agency for information about proper disposal options. If household garbage disposal is the only option, EPA recommends that certain precautions be taken. Since CFLs discarded in the trash will likely break and release mercury, EPA recommends that bulbs be put in two plastic bags and sealed before placement in outdoor trash or a protected outdoor location. Since virtually all components of a fluorescent bulb can be recycled, EPA recommends recycling as the preferred method to manage spent CFLs. The scope of programs to recycle CFLs varies from state to state. For example, a recycling program operating in Minnesota allows residents to leave CFLs at any of hundreds of retail stores across the state. A program in Indiana accepts CFLs at certain Sears stores. Also, regional groups have formed to develop recycling options. For example, the Northwest Compact Fluorescent Lamp Recycling Project is in the process of designing a pilot project to recycle CFLs in Oregon and Washington.