The 5 Biggest Sources of Mercury Pollution

Mercury is an overlooked component of air pollution. Here are 5 offenders, and some ways to clear the air.

July 22, 2009

More expensive than it looks: Polluted air is an often unmentioned cost of mining gold.

Warnings about mercury in fish and seafood have gotten plenty of attention in recent years. But where does all that mercury come from in the first place? Apparently, the largest sources of mercury emissions into our air and water are going all but unnoticed. A new study published in the Journal of Environmental Monitoring has found that mercury in the atmosphere is an oft-ignored form of air pollution, especially in urban areas where concentrations can reach dangerously high levels. The U.S. Environmental Protection Agency (EPA) has been lax in its enforcement of mercury-pollution standards over the past decade, exempting major polluters. Mercury is a neurotoxin that can harm the developing brains of children and infants; in adults, exposure can lead to memory loss and affect fertility and blood pressure.

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Here are the biggest emitters of mercury into the environment:

1. Coal-fired power plants. Mercury exists naturally in coal, making coal-fired power plants the largest source of mercury pollution in this country. Coal accounts for nearly 50 percent of the electricity generated in this country—and almost 50 tons of mercury emissions annually.

What you can do: Contact your electricity provider to see if buying green power is an alternative in your area. If it is, opt to get your energy from a less polluting source, such as wind, solar, or hydroelectric power.

2. Cement kilns. According to the nonprofit law firm Earthjustice, all the cement kilns in the U.S. combined pump out roughly 23,000 pounds of mercury every year. The mercury comes from coal, which is used to fuel the cement-manufacturing process, as well as limestone, another natural source of the heavy metal. The group released a report last July finding that, individually, some cement kilns emit nearly one and a half times more mercury than the most polluting coal-fired power plants. But because there are fewer kilns, they account for lower levels of atmospheric mercury overall than coal plants.

What you can do: Cleaning up this industrial process will take more political power than individual action, but you can lobby your local officials to put pressure on nearby cement kilns to clean up their acts. See if you live near a cement production facility by searching Earthjustice’s interactive map. If you do, support local environmental groups working for stricter mercury controls. You can also buy a water filter that’s certified to remove mercury from your drinking water, which will cut down on some of your exposure.

3. Chlor-alkali plants. Chlorine bleach, laundry detergent, cheap vinyl purses, shoes, and toys made with polyvinyl chloride (or PVC)—making all these products required the use of chlorine gas at some point. The chlor-alkali plants that produce it use mercury to convert salt to chlorine gas, and to convert salt to caustic soda, or lye, which is then used in products like detergent, plastics, and bleach. The nonprofit Natural Resources Defense Council (NRDC) says that while most modern chlor-alkali plants have switched to mercury-free technology, there are still seven plants in the U.S. that use it, and each one has roughly 200 tons of mercury on site at any given time. An unknown amount of that mercury gets lost during manufacturing, whether to the air or surrounding waterways; a 2006 report from NRDC found that operators at four of these plants could account for only 29 of the 159 tons of the mercury they used from 2000 to 2004. (As Rodale News reported earlier this year, some of those plants also make the ubiquitous food ingredient high-fructose corn syrup, and may be tainting food products with mercury.)

What you can do: Avoid chlorine-containing products like chlorine bleach, as well as anything made from polyvinyl chloride, including cheap handbags and shower curtains. Also look for chlorine-free paper products; paper production is the sixth largest mercury emitter in this country. Buy unbleached paper towels, coffee filters, and office paper. For the latter, look for the “Totally Chlorine Free” or “Processed Chlorine Free” labels on the package.

4. Trash incinerators. Hazardous waste, medical waste, and regular garbage incinerators release 13.1 tons (or about 26,000 pounds) of mercury every year, according to statistics from the EPA. The mercury comes from common household items, such as compact fluorescent light bulbs and thermostats, and from automobile scrap. Despite common perceptions that mercury is used in thermometers and blood pressure machines, the medical industry has switched to mercury-free versions of those tools, and medical waste now accounts for the smallest percentage of mercury emissions from incinerators.

What you can do: Visit Environment, Health and Safety Online to see if an incinerator is located near you. Support local efforts to implement stricter mercury controls, and filter your water.

5. Gold mining. According to those same EPA statistics, 11.5 tons of mercury each year are released from gold mining, often called the most polluting industry in the world. Historically, mercury was used to separate gold from mined ore, but in Nevada, which accounts for 80 percent of the gold mined in the U.S., the ore itself contains mercury. The mercury is released when gold is heated to separate the two. The nonprofit group Earthworks estimates that gold mines account for nearly 25 percent of the mercury emissions west of Texas, and it’s not just the existing mines that pose problems. Mercury can seep out of long-abandoned gold mines, most of which are in California, which continue to release mercury from underground pools of mine tailings, despite the fact that they’ve been closed since the end of the 19th century. The U.S. Geological Survey estimates that mine waters and sediments in these areas today release hundreds to thousands of pounds of mercury every year.

What you can do: Some major retailers, such as Tiffany & Co., have pledged to use only responsibly mined gold, free of mercury and other pollutants like cyanide. But the greenest, and cheapest, thing to do is opt for antique or estate jewelry when you’re shopping for bling.