Amateur radio has been subject to a requirement to meet the RF-exposure limits that apply to virtually all radio transmitters for over 25 years. Older rules had different evaluation requirements and different exemptions from the need to do evaluations for each separate radio service. The new rules change this and set a single, formula-based criterion for all radio services to determine whether an evaluation is required. This criterion is a formula in the rules that take into account transmit power, antenna gain and frequency.
While application of the rules has changed, the underlying substance has not. Knowledge of the FCC’s RF-exposure rules has long been required of examinees for all class levels of amateur licenses, and amateurs continue to be required to certify on their FCC Form 605 applications that they comply and will comply with the requirements of the FCC RF-exposure rules. The rules change allows stations that complied with the old rules to continue to be operated under the old rules until May 3, 2023. If you were exempt from the requirement to evaluate your station under the old rules, by May 3, 2023, you will need to determine that you are still exempt using the new criteria for exemption described in the new rules or perform an evaluation. If you have previously evaluated your station, the evaluation is still valid, so you will not need to do the same evaluation again in two years unless you make RF-safety related changes to your station. If you make a change to your station after May 3, 2021 that could affect RF exposure, such as increasing your transmitter power, putting up a new antenna or moving an existing antenna, you need to calculate whether you are exempt from the requirement or do an evaluation before you put your changed station into operation.
Under the old rules, many amateurs were categorically exempt from the need to do an evaluation, based on transmitter power on each band, for example. Under the new rules, there are no longer any service-specific exemptions. These have been replaced with formulas that can be used to determine whether a specific installation needs to be evaluated. The formulas can be used for exposure that is beyond the near-field, far-field boundary of your antenna, defined as wavelength/2π, or 0.16 wavelength. Most stations that were exempt under the old rules will still be exempt from the need to perform a more complete evaluation under the new rules. In many cases, using one of the on-line web pages to do a calculation is just as easy as doing the calculation to see if you are exempt.
Here is a list of sites where you can perform an RF Exposure calculation for your station.
Lake Washington Ham Club RF Exposure Calculator (good supporting info)