Mr. Stephen Meer of The Sigma Group, Inc. recently completed certification for residential radon measurement and mitigation through the National Radon Proficiency Program (NRPP). Evaluating and mitigating potential vapor intrusion risk is an important component of many brownfield redevelopment projects. WDNR recommends vapor intrusion mitigation be performed by NRPP-certified professionals – Sigma personnel are now NRPP certified, an added benefit to our already well qualified and experienced team.