What Is Fly Ash?
The EPA says coal combustion residuals, or coal ash, are produced primarily from burning coal in coal-fired power plants, and include fly ash, a very fine, powdery material composed mostly of silica made from the burning of finely ground coal in a boiler.
The EPA says coal ash contains contaminants like mercury, cadmium and arsenic, and that without proper management these contaminants can pollute waterways, ground water, drinking water and the air.
Much of it is reused. The EPA says encapsulated uses bind coal ash in products such as wallboard, concrete, roofing materials and bricks in a way that minimizes it escaping into the surrounding environment, and that one of the two largest encapsulated uses is fly ash in concrete, concrete products and grout.
Federal rules are still changing. The EPA's first national coal ash disposal rule was signed December 19, 2014 and published in the Federal Register on April 17, 2015. On May 8, 2024, the EPA finalized changes for inactive surface impoundments at inactive power plants, known as legacy CCR surface impoundments, and on April 9, 2026 it announced a proposal to amend several provisions of its coal ash disposal and beneficial use regulations, taking comments through June 29, 2026.
Sources checked September 15, 2026. Every point below links the page it came from.
The sources behind this answer
- Medical referenceThe EPA says coal combustion residuals include fly ash, a very fine, powdery material composed mostly of silica made from burning finely ground coal in a boiler. US EPA ↗
- Government sourceThe EPA says coal ash contains contaminants like mercury, cadmium and arsenic that, without proper management, can pollute waterways, ground water, drinking water and the air. US EPA ↗
- Government sourceThe EPA says encapsulated uses bind coal ash in products such as wallboard, concrete and bricks, and that fly ash in concrete, concrete products and grout is one of the two largest. US EPA ↗
- Regulatory filingThe EPA's Disposal of Coal Combustion Residuals from Electric Utilities final rule was signed December 19, 2014 and published in the Federal Register on April 17, 2015. US EPA ↗
- Regulatory filingOn May 8, 2024, the EPA finalized coal ash rule changes for inactive surface impoundments at inactive electric utilities, called legacy CCR surface impoundments. US EPA ↗
- Regulatory filingOn April 9, 2026, the EPA announced a proposal to amend several provisions of its coal ash disposal and beneficial use regulations, accepting comments through June 29, 2026. US EPA ↗
Sources checked September 15, 2026. A brand statement is the company’s own claim, which we report but have not verified. Our grades are model-based estimates, not lab tests.