voluntarily capped the amount of mercury used in CFLs. In the EU the same cap is required by the RoHS law. In areas where electric power is mostly generated in coal-fired stations, replacing incandescent bulbs by CFLs actually reduces mercury emissions. This is because the reduced electric power demand, reducing in turn the amount of mercury released by coal as it is burned, more than offsets the amount of mercury released from broken and discarded CFL bulbs. In July 2008 the U.S. EPA published a data sheet stating that the net system emission of mercury for CFL lighting was lower than for incandescent lighting of comparable lumen output. This was based on the average rate of mercury emission for U.S. electricity production and average estimated escape of mercury from a CFL put into a landfill. Coal-fired plants also emit other heavy metals, sulfur, and carbon dioxide. In the United States, the U.S. Environmental Protection Agency estimated that if all 270 million CFLs sold in 2007 were sent to landfill sites, around 0.13 metric tons of mercury would be released, 0.1% of all U.S. emissions of mercury (around 104 metric tons that year). The graph assumes that CFLs last an average of 8,000 hours regardless of manufacturer and premature breakage. In areas where coal is not used to produce energy, the emissions would be less for both types of bulb. Special handling instructions for breakage are not printed on the packaging of household CFL bulbs in many countries. The amount of mercury released by one bulb can temporarily exceed U.S. federal guidelines for chronic exposure. Chronic, however, implies exposure for a significant time, and it remains unclear what the health risks are from short-term exposure to low levels of elemental mercury. Despite following EPA best-practice clean-up guidelines on broken CFLs, researchers were unable to remove mercury from carpet, and agitation of the carpet — such as by young children playing — created localized concentrations as high as 0.025 mg/m3 in air close to the carpet, even weeks after the initial breakage. The U.S. Environmental Protection Agency (EPA) has published best practices for cleanup of broken CFLs, and ways to avoid breakage, on its web site. It recommends airing out the room and carefully disposing of broken pieces in a jar. A Maine Department of Environmental Protection (DEP) study of 2008 comparing clean-up methods warns that using plastic bags to store broken