---
title: "MATS (US Mercury and Air Toxics)"
description: "MATS (Mercury and Air Toxics Standards) is the US EPA's rule setting national emission limits for mercury, acid gases and other hazardous air pollutants from coal-fired and oil-fired electric utility steam generators. Promulgated in 2012, MATS drove substantial retrofit investment in US power-plant pollution control through the 2010s."
canonical_url: "https://sylio.co/glossary/mats-us-mercury-and-air-toxics"
last_updated: "2026-06-28T02:29:39.798Z"
---

**MATS** (Mercury and Air Toxics Standards) is the US EPA's rule setting national emission limits for mercury, acid gases and other hazardous air pollutants from coal-fired and oil-fired electric utility steam generators. Promulgated in 2012, MATS drove substantial retrofit investment in US power-plant pollution control through the 2010s.

## Industrial implications

MATS compliance often requires retrofitting:

- Activated-carbon injection for mercury
- Dry sorbent injection or wet FGD for acid gases
- Higher-efficiency [baghouses](/glossary/baghouse) or upgraded [ESPs](/glossary/electrostatic-precipitator) for particulate-bound metals
- Continuous emissions monitoring upgrades

[Sonic horns](/glossary/sonic-horn) installed during MATS-driven retrofits help maintain the achieved compliance margin over the operating cycle — preserving ESP/baghouse performance against the fouling that would otherwise erode it.

## Related terms

- [EPA NSPS](/glossary/epa-nsps)
- [Electrostatic precipitator](/glossary/electrostatic-precipitator)
- [Baghouse](/glossary/baghouse)