Radon-Reporter-2026-Issue-1FINAL

6 | APRIL 2026 ASSOCIATION NEWS Where System Design Diverges The differences between radon and vapor intrusion mitigation begin immediately. Vapor intrusion projects require a larger, more specialized team: environmental consultants to identify contaminants, regulators to review plans, and mitigation designers who understand how chemicals behave in the subsurface. Materials must be selected based on chemical compatibility, and standard radon fans or vapor barriers may not be appropriate. McDonald notes that the engineering expectations are also dramatically different. Every vapor intrusion system that his firm installs begins with CAD drawings, formal reviews, and multiple approvals. “There’s no such thing as design on the fly,” he says. “When we turn a system on, it has to work the first time.” Pilot testing is equally demanding. Subsurface conditions rarely behave in the neat, circular patterns shown in textbooks. Buildings with multiple additions, inconsistent aggregate layers, or structural constraints require careful interpretation of pressure field data and often more conservative design choices. The Challenge of Verification If design is complex, verification is even more so. Unlike radon, where post-mitigation testing is straightforward, vapor intrusion verification must contend with a world full of volatile organic compounds. New carpets, fresh paint, adhesives, cabinetry, and furniture all off-gas VOCs that can obscure or mimic subsurface contamination. Peterson explains that this makes sampling interpretation especially challenging. “You will find VOCs in almost any building,” she says. “The question is whether they’re coming from the subsurface or from the materials inside the space.” McDonald adds that even when a system is functioning properly, verification can be complicated by fan failures, building owner behavior, or incomplete delineation of the treatment area. In one case, he recalls, a building owner simply not wanting to run the system at night, so he would turn it off - a detail that explained unexpected test results. A Team Sport, Not a Solo Practice Both guests emphasize that vapor intrusion is not a one-person job. Successful projects require designers, consultants, regulators, and sometimes financial specialists who understand redevelopment incentives and grant structures. Just as important is knowing when not to step outside your expertise. “People ask me exposure questions all the time,” McDonald says. “That’s not my role. You need the right people at the table.” Why This Conversation Matters Vapor intrusion is no longer an emerging issue. It is a defining challenge for environmental professionals, builders, and policymakers. As Peterson and McDonald make clear, the work demands technical depth, collaboration, and a willingness to navigate complexity. For those working in radon, mitigation, environmental health, or consulting, this episode offers a grounded look at what it truly takes to design, install, and verify vapor intrusion systems in the field. Check out the full Episode 8 of The Indoor Environments Project It’s a timely, insightful conversation for anyone committed to advancing indoor environmental quality and staying ahead of the evolving demands of vapor intrusion work. The podcast has continued to expand the conversation Episodes 5 through 7 explore three topics that sit at the heart of the profession: standards development, emerging technologies, and the public health implications of radon exposure. Episode 5: Why Standards Matter Released November 26, 2025, Episode 5 focuses on the role that consensus standards play in protecting both professionals and the public. Host Diane Swecker speaks with Myca Bruno, Managing Director of Indoor Air Quality Assessment at BBG, member of the AARST Consortium’s Radon Measurement Standards Committee, and President of the IEA North Carolina Chapter, along with Shawn Price, Director of Operations for Air Chek and AccuStar Labs, former IEA President, Chair of the Standards Management Council, and Chair of the AARST Consortium’s Radon Measurement Standards Committee. Together, they explain what a consensus standard actually is and how the standards development process works. The