PITTSBURGH, September 26, 2024 – PRI Certification proudly joins US Steel Corporation’s (NYSE: X) Big River Steel in celebrating its achievement as the first ResponsibleSteel™ Certified in the world. The certification process was conducted by SRI Quality System Registrar, a PRI Certification subsidiary, and included a comprehensive audit with extensive document and records reviews.

This is an extraordinary accomplishment for PRI Certification’s group demonstrating leadership in enabling steel producers, and suppliers, to certify their sustainability progress to a comprehensive, credible global standard.

Ed Maschmeier, Vice President of PRI Certification, the company that conducted the third-party audit added, "Big River Steel has demonstrated its commitment to improving its responsible sourcing and site-level decarbonization. We are looking forward to working with them as they strive to achieve higher Progress levels over time.”

US Steel has consistently set industry milestones, from sustainable sourcing and production to achieving the first-ever ResponsibleSteel site certification in North America. Now, they have become the first company, globally, to offer ResponsibleSteel™ Certified Steel products at their Big River facility in Osceola, Arkansas.

While ResponsibleSteel™ is the only globally recognized standard covering responsible outsourcing and production for the steel industry, SRI Quality System Registrar, a PRI Certification subsidiary, is the only certification body in North America qualified to certify compliance with the environmentally sound standards established by ResponsibleSteel™.

Stakeholders increasingly demand responsibly sourced materials, and ResponsibleSteel™ certification helps drive climate change action.

Maschmeier added, "Steel Certification requires conformance with all progress criteria related to responsible sourcing and site-level decarbonization, and after a rigorous and thorough audit process, we have concluded they successfully demonstrated Progress Level 1."

### Note to editors: For more information on PRI Certification and additional services and programs, please visit Performance Review Institute (PRI) - We Protect What Matters (p-r-i.org) PRI Certification is a not-for-profit organization specializing in third-party management system certification services.

In 2024, the organization rebranded after acquiring SRI Quality System Registrar, MCNA, and Platinum Registrar, combining over 60 years of expertise. This merger strengthens its leadership in certification, addressing evolving needs in Quality, Data Security, Environmental, and Health & Safety standards.

The Performance Review Institute (PRI) is a not-for-profit trade association started in 1990. PRI is a global administrator of industry-managed critical process accreditation programs focused on improving process and quality with collaboration among stakeholders in industries where safety and quality are shared goals. Ashley Keibler, Marketing Coordinator – Communications at PRI, 724-772-4002 or akeibler@p- r-i.org.