MAMF_with 1-21 Revisions

MAMF/MALB Companion Guidance 2021 Section 2 Guidance to Building Managers 5 G. Retesting When Tests Have Indicated Low Radon Concentrations Retesting the building at least every 5 years is recommended. Testing may be conducted more often to gain more information. Many factors can cause indoor radon concentrations in a building to change over time. These changes may produce variations in radon concentrations compared to previous tests. It is recommended to test again when any of the following circumstances occur: ü A new addition is constructed or significant renovation takes place; ü A ground contact area not previously tested is occupied or subsequent to taking occupancy of a building; ü Heating or cooling systems are significantly altered resulting in changes to air pressures or distribution; ü Ventilation is significantly altered by extensive weatherization, changes to mechanical systems or comparable procedures; ü Significant openings to soil occur due to: - groundwater or slab surface water control systems (e.g., sumps, perimeter drain tile, shower/tub retrofits, etc.); or - natural settlement causing major cracks to develop; ü Earthquakes, construction blasting, or formation of sink holes nearby; or ü An installed mitigation system is altered, modified or repaired. H. Mitigation Timing How quickly to begin the mitigation process will depend on the initial radon concentration detected. Radon concentrations of more than twice the action level requires a more rapid response; e.g., more than 8 pCi/L (296 Bq/m 3 ). The Need for Professional Mitigation Guidance Lowering radon concentrations requires special training, skills and experience. Persons qualified in varied disciplines with different skill sets are often needed. It is critical that persons, including radon professionals, be qualified for their apportioned task. To successfully lower radon concentrations with confidence, the management team, contractor or contracting team needs to include individuals with experience in radon mitigation who have demonstrated a minimum degree of appropriate technical knowledge and skills specific to radon mitigation in the size of building being mitigated. Prior Design Diagnostics Conditions in the entire building must be evaluated. Diagnostic procedures to evaluate air pressure relationships within and under a building are needed to identify the appropriate radon reduction technique and design.