Energy-saving compact fluorescent lightbulbs can lead to an increase in mercury pollution in some regions, according to a new study published in the journal Environmental Science & Technology. The study looked at mercury emissions in 130 countries and all 50 U.S. states to determine what role CFLs, which contain mercury, may have in upping mercury pollution. The study concludes that, in general, areas that get most of their power from coal-fired power plants — such as China and Estonia — can reduce their net mercury emissions overall by switching to CFLs since the bulbs help reduce electricity demand and thereby also reduce mercury pollution from coal plants. However, in areas where few coal-fired power plants are in operation, such as California and much of South America, CFL use may actually increase an area’s overall mercury pollution since the toxic element can be released upon breakage or disposal of the bulbs. Other factors to consider, the study says, include the kind of coal burned in nearby coal plants and the availability of CFL recycling programs. Still, of course, CFLs save a significant amount of energy and prevent greenhouse-gas emissions — one reason why Umbra Fisk has advised their use even though they contain mercury.