IEA Radon_Reporter_April 2025

THE RADON REPORTER | 17 VAPOR INTRUSION TABLE 2. SUMMARY OF MITIGATION GUIDELINES State Recommended Differential Pressure Target (range or min) (Pa) Recommended Vapor Membrane Thickness (range or min) (mil) Designer Qualification Assumptions Emission Control Assumptions Assumed Emission Threshold for Permit and/or Controls** (typically total VOCs) Alaska Measurable Vacuum - - - - California - DTSC (2011) 4-10 60 PE Emission based - California - RWQCB (2022) 4 30-60 PE Emission based Per Air Quality Management District Colorado 5* 15-30 - - - Delaware - - - Emission based > 0.2 lbs/day Georgia 1 30 QP - - Illinois 0.75 60 - - - Indiana Measurable Vacuum - - - - Maine - - RRM Emission based By Compound Massachusetts 3-5 40-100 QP Emission based, specific to mitigation systems > 100 lbs/year Michigan Measurable Vacuum - PE Emission Based/ Residential Systems Exempt By Compound Minnesota 3 - 5 - RRM or QP - - Montana - 3-6 PE Initial Controls Needed EPA RSLs New Hampshire - - RRM or QP - - New Jersey 1 40 RRM or PE Emission Based/ Residential Systems Exempt >0.1 lbs/hour New York - 3-6 QP or PE Systems Exempt - North Carolina 4* - PE - - Ohio 5 10-60 - Emission based > 10 lbs/day Oregon - - PE Emission based By Compound Pennsylvania 2-6 - RRM Emission based > 2.7 tons/year Tennessee 1 - - Emission based >1,000 lbs/year Vermont 2 - - Emission based By Compound Washington - - PE Emission based By Compound West Virginia - - QP - - Wisconsin 1 30 RRM or QP Emission based > 5.7 lbs/hr Wyoming - - QP - - DC - 30-60 - - - NOTES: * = Accommodations may be made if values are less than the recommended minimum differential pressure. ** = Values provided represent emissions stated in guidance or easily found via reference. Thresholds represent emission limit printed in guidance or regulation and represent values listed for groups of compounds (e.g., total VOCs, total hazardous air pollutants, etc.). Practitioners should verify values for site-specific scenarios. - = No significant information provided. RRM = Registered Radon Mitigator (i.e., nationally and/or state recognized). PE = Professional Engineer. QP = Qualified Professional (i.e., holds a relevant degree or license or has applicable experience).