Standards Adopted in by States in the US
Many states across the US have adopted standards of practice relating to radon.
You must meet these standards when working within the state. If you are NRPP/NRSB certified you must meet the state requirements and then if the NRPP/NRSB certification standards are more strict you will be expected to meet those guidelines as long as they do not conflict with the state requirements.
EPA Webinar Recording from May 31, 2023