From the ARRL:

As detailed in a May 2023 QST article by Greg Lapin, N9GL, the rules which took effect on May 3, 2021 now require amateur radio operators to perform station evaluations.  The Amateur Radio Service is no longer categorically excluded from certain aspects of the RF exposure rules, and licensees can no longer avoid performing an exposure assessment simply because they are transmitting below a given power level.  

A two year transition period was implemented to allow existing stations to make any necessary changes, but as of May 3, 2023, the transition period ends and all transmitters operating in the US are expected to comply with the exposure rules.  The ARRL has on its website an RF Exposure Calculator to assist amateurs in performing station assessments.

To continue reading and for an assortment of helpful RF exposure calculation resources, visit http://www.arrl.org/rf-exposure