Updated February 2025
The National Emission Standards for Hazardous Air Pollutants for Coal- and Oil-Fired Electric Utility Steam Generating Units (EGUs), also known as the Mercury & Air Toxics Standards (MATS), sets technology-based emissions standards for mercury and other hazardous air pollutants (HAPs) emitted by coal and oil-fired EGUs with a capacity of more than 25 megawatts. MATS first came into effect in 2012 and received a recent update in 2024, significantly tightening emissions standards.
The implementation of the MATS and other changes in the power sector have successfully reduced a wide range of air pollutant emissions. Industry-reported emissions data, required by MATS, shows 2021 mercury emissions from coal-fired EGUs were 90 percent lower than pre-MATS levels. Acid gas HAP and non-mercury metals are down 96% and 81%, respectively, compared to 2010 levels.
Mercury & Air Toxics Standards Requirements
The Mercury & Air Toxics Standards limit emissions for a variety of pollutants, including mercury, acid gas hazardous air pollutants such as hydrogen chloride and hydrogen fluoride, non-mercury HAP metals such as nickel, lead, and chromium, and organic HAP such as formaldehyde and dioxins/furans from coal- and oil-fired power plants.
Organizations must report emissions of pollutants specified by the MATS, along with information on their monitoring methods. There are also specific requirements for performance tests, deviations, and other important data.
The 2024 update significantly reduced the emissions standard for filterable particulate matter, which serves as a surrogate emissions standard to control non-mercury HAP metals. Along with reducing this limit by two-thirds, the EPA is also finalizing the removal of low-emitting EGU exceptions.
The allowable limit for mercury emissions for existing lignite-fired power plants is being reduced by 70%. This aligns lignite-fired plants with the standard that other coal-fired plants have already been achieving under previous MATS requirements.
Monitoring and compliance have been strengthened as well. Coal and oil-fired EGUs must now demonstrate compliance by using PM continuous emission monitoring systems to measure filterable particulate matter.
Keeping Up With MATS Compliance
Maintaining compliance requires the collection, management, and submission of substantial emissions monitoring data. ERA’s Environmental Management System provides your team with the tools to track this data and streamline reporting. You can ensure accurate and complete reporting to avoid penalties from the EPA. Book a discovery call today to discover how ERA’s software can support your team.
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