Radon-Reporter-2026-Issue-1FINAL

22 | APRIL 2026 When the Interstate Technology & Regulatory Council (ITRC) released its updated Vapor Intrusion Toolkit in January 2026, it marked one of the most significant advancements in vapor intrusion guidance in more than a decade. The new toolkit replaces and integrates earlier documents, (VI-1, PVI-1, and VIM-1), into a single, comprehensive resource that reflects the rapid evolution of vapor intrusion science, regulatory expectations, and field practice. For environmental consultants, regulators, and mitigation professionals, this update arrives at a pivotal moment. Vapor intrusion is no longer a niche concern; it is a central factor in redevelopment, environmental due diligence, and long- term building performance. The 2026 toolkit provides the clarity, structure, and technical depth needed to navigate this increasingly complex landscape. A Modernized Framework for a Modern Challenge The new toolkit is more than a revision — it is a rethinking of how vapor intrusion should be assessed and managed. ITRC’s update reflects major advancements in conceptual site modeling, investigation techniques, and mitigation system design. It also incorporates lessons learned from hundreds of real-world projects across the country, offering practitioners a more defensible and consistent approach to decision-making. The guidance is intentionally practical. It walks users through the entire vapor intrusion process, from initial screening and pathway evaluation to mitigation selection, system verification, and long-term operation and maintenance. The result is a resource that supports both seasoned experts and professionals newly entering the field. What’s New in the 2026 Toolkit One of the most notable strengths of the updated toolkit is its integration of previously separate guidance documents into a unified, streamlined resource. This consolidation eliminates redundancy and ensures that investigation and mitigation guidance are aligned. This is a major improvement for practitioners who previously had to navigate multiple documents. The 2026 update also reflects advances in vapor intrusion science, updated regulatory perspectives, enhancedmitigation guidance, and new training pathways. These updates make the toolkit not only more comprehensive, but also more aligned with the realities of today’s vapor intrusion work where redevelopment pressures, community expectations, and regulatory scrutiny continue to rise. A Collaborative Effort Behind the Scenes The 2026 toolkit reflects the work of a broad coalition of environmental professionals, regulators, academics, and industry leaders. ITRC’s model where a state-led, multi-stakeholder collaboration ensures that the guidance is grounded in both scientific rigor and practical field experience. Contributors from consulting firms, state agencies, and mitigation companies helped shape the document, bringing diverse perspectives on investigation challenges, system performance, and community engagement. ITRC’s collaborative, multi‑stakeholder approach is one reason its guidance is widely referenced by agencies and practitioners across the country. A New Era for Vapor Intrusion Practice: Inside the 2026 ITRC Vapor Intrusion Toolkit How the 2026 ITRC VI Toolkit Evolved The 2026 Interstate Technology & Regulatory Council (ITRC) Vapor Intrusion Toolkit consolidates and updates three earlier guidance documents: • VI‑1 (Vapor Intrusion Guidance) • PVI‑1 (Petroleum Vapor Intrusion Guidance) • VIM‑1 (Vapor Intrusion Mitigation Guidance) This unified toolkit streamlines investigation and mitigation concepts into a single, modern resource. The update reflects advances in conceptual site modeling, sampling methods, mitigation technologies, and long‑term stewardship practices. By integrating these previously separate documents, ITRC provides practitioners with a clearer, more cohesive framework for evaluating and managing vapor intrusion at a wide range of sites. VAPOR INTRUSION