Cement kilns are the source of numerous pollutants known to be toxic, including arsenic, benzene, dioxins, formaldehyde, hydrogen chloride, lead, mercury, and xylene. There are regulations addressing some of these emissions, for some kilns.
But some state government agencies and environmental, health, and industry groups have been challenging the existing EPA regulations, or lack thereof, for years. As part of a proposed court settlement that was driven by one of the latest of those efforts, and is open for public comment until Feb. 25, 2009, EPA is scheduled to release on March 31, 2009, a proposed rule that addresses emissions of mercury, hydrogen chloride (which forms hydrochloric acid), and total hydrocarbons from kilns that are fueled by coal or other typical fuels, or what EPA has deemed to be nonhazardous waste. If EPA doesn't meet that date, lawsuits could resume.
The current consolidated lawsuits challenged EPA's final rule of Dec. 20, 2006, that addressed selected aspects of cement kiln emissions. A final rule responding to the current legal action is required by March 31, 2010, if the settlement holds.
Parties to the current lawsuit include 6 organizations represented by Earthjustice (Sierra Club, Downwinders at Risk (TX), Friends of Hudson (NY), Montanans Against Toxic Burning (MT), Desert Citizens Against Pollution (CA), and the Huron Environmental Activist League (MI)), the Portland Cement Association, and the states (or agencies in them) of CT, DE, IL, MA, MI, NJ, NY, and PA.
- EPA: Rule and Implementation Information for Portland Cement Manufacturing Industry  (includes current proposed settlement, 2006 rule, and many older rules and related information).
There are about 150 kilns at approximately 100 plants that likely would be covered by the upcoming rule. At least 33 states and Puerto Rico have kilns, including AL, AZ, CA, CO, FL, GA, IA, ID, IL, IN, KS, KY, MD, ME, MI, MO, MT, NE, NM, NV, NY, OH, OK, OR, PA, SC, SD, TN, TX, UT, VA, WA, and WY.
The kilns, are covered in some detail in a July 2008 report by Earthjustice and the Environmental Integrity Project that focused on mercury emissions. About 20 other plants not covered in the report use fuel that EPA deems to be hazardous waste. A new rule for these kilns is being developed by EPA's Office OF Solid Waste and Emergency Response, but its timeline is uncertain.
- "Cementing a Toxic Legacy?"  Earthjustice, Jim Pew,  202-667-4500 x214; Environmental Integrity Project, Eric Schaeffer,  202-296-8800 x1.
The advocacy group report was based in part on selected, self-reported industry data EPA acquired in 2007 that showed that the agency's previous estimate of mercury emissions from the 150 kilns that burn nonhazardous waste missed about half the total. The gap may be much worse than that, if the report's critique of some potentially major limitations in EPA's updated numbers proves valid.
Even if EPA's numbers are viable, at least one kiln, at the Ash Grove plant in Durkee, OR, has mercury emissions of at least 2,582 pounds per year, and the advocacy report estimates it's possibly as high as 3,788 pounds per year. Even with EPA's low number, that's worse than the worst power plant in the country, which the advocacy groups say emits 1,700 pounds per year.
All told, the existing kilns that burn what has been deemed nonhazardous waste for fuel likely emit at least 22,914 pounds of mercury per year, and the number could be in the range of 27,500 pounds, according to the advocacy groups.
Until now, mercury emissions from cement kilns have not merited separate mention on EPA's Web site addressing this issue. Industries, businesses, and products that have been given emphasis include coal-fired power plants, health care and dental providers, the chlor-alkali industry, the iron and steel industry, the auto industry, the solid waste management industry, sewage treatment plants, and appliances, automobiles, and some light bulbs.
- EPA: Mercury: Business and Industry. 
Additional information on EPA's approach to and former agenda for mercury is available at:
Keep in mind that EPA has just indicated that it will be revisiting its former rule, advocated during the Bush administration, addressing mercury emissions from power plants. The timeline for a new proposal is uncertain.
EPA information on its 1999 rule and 2005 amendment for fuel derived from hazardous waste is at:
- EPA: Hazardous Waste Combustion. 
The Cement Kiln Recycling Coalition could be a useful source to talk with regarding the later rule for kilns that burn hazardous waste (and possibly for the March 2009 proposed rule, depending on the angles your story takes). The CKRC says that the cement industry annually fuels its kilns with over one million tons of hazardous waste, including used paint solvents, discarded paints and coatings, inks and ink solvents, various resins and organic sludges, and petroleum refining chemical manufacturing by-products.
The Portland Cement Association (PCA) says that used tires also are an acceptable fuel source.
- PCA: Nov. 20, 2008, press release. 
- PCA: basic kiln and cement industry information: manufacturing  and flash tour of the cement-making process. 
In related action, EPA is currently in litigation with Earthjustice over rules for hazardous waste combustion. Earthjustice's Jim Pew says that EPA has voluntarily withdrawn a related rule for now, and that his organization is waiting to see what actions the agency takes, or doesn't take, under the new administration before deciding whether to continue with the lawsuit. There is no fixed timetable for the next steps.
To find the type and quantity of reported emissions from kilns of all types, check sources such as AirData (for the full range of criteria air pollutants) or the Toxics Release Inventory.