Why An indoor antenna puts the radiating element inside living or working space, where people are continuously present, so the controlling factor is the FCC maximum permissible exposure (MPE) limits in Part 97.13(c) and OET Bulletin 65. You must run a station evaluation and confirm that field strength or power density in any occupied area stays below the applicable limit, using distance, lower power, or reduced duty cycle as needed. Uncontrolled-environment limits (averaged over 30 minutes) apply to family members and neighbors who have not been made aware of the exposure.
Watch out Putting the antenna close to the operating position is exactly backwards, since distance is your main tool for reducing exposure. An antenna that radiates cannot be shielded without defeating its purpose.
Indoor antenna means people nearby: the only real precaution is staying under MPE limits in occupied spaces.