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Fly Ash in Building Products: Handle with extreme care

September 15, 2010

Publisher’s Note: We reprint the following article which appeared in today’s Healthy Building News with the permission of its author, Bill Walsh, Executive Director of the Healthy Building Network. When it comes accurate information on toxic building materials and their safe alternatives there is no more trustworthy source than Bill and HBN. For many years he has been a leader in the battle to rid homes of materials containing PVC (polyvinyl chloride) — which has a poisonous life cycle from its manufacture to home to landfill or incinerator. Here he tackles a critical issue — what to do with the massive amounts of ash produced by coal burning power plants. Environmentalists and community activists are pressing EPA to regulate coal ash as a hazardous waste — which help to stop dangerous disposal practices. In addition to fighting this proposal the coal industry and its allies in the building material sector want the freedom to use the ash for so-called beneficial uses. EPA is trying to make its mind up on what “beneficial uses” to allow and what restrictions to impose. Bill Walsh has a lot to say on the subject.



By Bill Walsh  Healthy Building Network
September 15, 2010

Bill Walsh, Executive Director of the Healthy Building Network

On September 1, 2010, Environmental Building News (EBN) announced it would “no longer consider the use of fly ash in products or materials to be an environmental attribute when doing so does not offset greenhouse gas emissions.” EBN continues to support the use fly ash as a substitute for portland cement in concrete. In his editorial explaining the EBN position, Executive Director Alex Wilson also called for transparency and disclosure standards that allow purchasers to know the “hazard concentration grade” of toxic materials such as mercury that are frequently found in fly ash. The Green Guide for Health Care, the California Collaborative on High Performance Schools and the draft LEED for Health Care also set strict limits on mercury levels in fly ash in all applications, including those which offset greenhouse gases, such as cement.

The EBN position is the latest significant rebuke to regulations recently proposed by the EPA that aggressively promote unregulated recycling, or “beneficial use,” of fly ash and other waste products from coal-burning power plants. These have been challenged by Public Employees for Environmental Responsibility (PEER) for lacking “demonstrated scientific support for the safety or quantifiable benefits of using coal combustion wastes in building and consumer products.” 

One major concern is that as air pollution control technology gets better, larger concentrations of contaminants such as heavy metals are “scrubbed” from the gases and concentrated in various waste streams: fly ash, bottom ash, or materials from the stack known as “flue gas desulfurization residuals.” Each waste stream has its own issues. These will vary depending upon the composition of the coal, although heavy metals like lead, arsenic and mercury are common concerns with all.

One of the big problems with EPA’s vigorous support for recycling coal combustion waste is that it contradicts the Agency’s 2006 Roadmap for Mercury, the national long- term strategy for reducing ubiquitous mercury contamination of our environment, food chain and bodies. In that plan, EPA invites companies to “voluntarily commit to mercury product use reduction and phaseout goals and … to establish inventories of mercury; remove mercury and mercury-containing equipment from their plants; and institute purchasing policies to reduce mercury use.”

Promoters of fly ash and other coal combustion wastes as “recycled content” cite early studies that have not detected mercury leaching from concrete products made with fly ash. But according to the EPA: “When mercury is used in a product, most releases occur during manufacturing or disposal.” Indeed, elevated mercury releases have been documented in wallboard manufacturing plants that use coal combustion wastes, and in December 2009, the State of New York revoked a 20-year-old “beneficial use” designation for fly ash used at a cement kiln due to elevated mercury levels in nearby soil and wildlife. No testing has yet been done to assess the potential mercury exposure to workers in those facilities, or in jobs that involve grinding or jackhammering concrete, or crushing it for recycling at end of life.

The air pollution laws that mandate the “scrubbing” of toxic pollutants out of coal combustion gasses are one of the great successes of the Clean Air Act, an example of how to properly allocate pollution costs that were once externalized. No studies have been done to determine whether widespread dispersal of mercury and other heavy metals into building products could undermine this formula and transform concentrated regulated “point sources” of mercury and other heavy metals into countless “non-point sources” that are impossible to control over the long term.

Another big problem is that the “coal ash reuse industry” has aligned itself with the coal industry, opposing efforts by environmental groups like the Sierra Club, Earth Justice, Southern Environmental Law Center and PEER to strictly regulate coal combustion wastes and reduce carbon emissions. The long-term cost of storing and managing contaminated coal ash provides an economic incentive for utilities and their customers to use coal-generated power more efficiently and to switch to renewable energy sources. No studies have been conducted to determine whether the unregulated recycling of coal combustion wastes might inhibit efforts to reduce overall carbon emissions to the atmosphere from coal-burning power plants.

Fly ash can replace up to 25 % of the Portland cement used in concrete. Concrete on sidewalks, roads and other outdoor surfaces is subject to abrasion and weathering processes. How much mercury or lead will escape into the environment? Source:

Before taking a neurotoxic waste material such as mercury out of a successful pollution control program and redistributing it into our homes, schools and job sites, we should take reasonable precautions. Among these would be fairly simple tests to ensure that mercury and other heavy metals do not escape during manufacturing, construction, recycling or disposal of products made from coal combustion wastes; regulations limiting the range of toxic materials in the material, and transparent monitoring and disclosure of those contents.


In its proposed rule, EPA emphasizes repeatedly that it does not wish to “stigmatize” fly ash by designating it as a hazardous waste. The greater concern is this: that by following the lead of the coal industry rather than taking the time to do due diligence, EPA – and the coal ash reuse industry – are leaving the green building industry vulnerable to the stigma of potentially widespread heavy metal contamination in recycled products.



[1] PEER Comments CCR Proposed Rule., p.1.

[2] U.S. ENVTL. PROTECTION AGENCY, EPA’S ROADMAP FOR MERCURY, EPA-HQ-OPPT-2005-0013 (2006), p.3, Roadmap-6-29.pdf.


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