In December 2019, the FCC finally took action in its open docket on radiofrequency (RF) exposure (RFE), adopting a Resolution of Notice of Inquiry, Second Report and Order, Notice of Proposed Rulemaking, and Memorandum Opinion and Order. Therein, the FCC addressed many issues which had been pending since 2013 when the FCC issued a First Report and Order, Further Notice of Proposed Rulemaking, and Notice of Inquiry, each addressing various issues related to RFE. (See blog entries dated February 8, February 22, and March 1, 2018, for information regarding the 2013 FCC actions.)

Radiofrequency Exposure Limits Unchanged

In the matter of greatest interest to the public, the FCC determined in its Resolution of Notice of Inquiry that no changes should be made to its existing RF exposure limits, which have been in place since their adoption by the FCC in 1996. The FCC stated, “we believe they reflect the best available information concerning safe levels of RF exposure for workers and members of the general public…” In so deciding, the FCC relied heavily on input from other federal agencies charged with regulating safety and health and “the lack of data in the record to support modifying our existing exposure limits.”

The current FCC limits differentiate between general public and occupational/controlled exposure limits. The latter apply to personnel with expertise and training regarding RF exposure safety, and their exposure levels are higher than for the general public.

In other actions related to the 2013 Notice of Inquiry, the FCC declined to revisit its RF exposure evaluation procedures for consumer portable devices, especially phones; declined to revisit its RF exposure policy as it pertains to children; and said it will continue to ensure that relevant information is made available to the public.

Changes to Application of the Limits

The FCC resolved the 2013 Further Notice of Proposed Rulemaking issues in its Second Report and Order, which has three main parts:

     A. Identifying broad criteria that apply to single and multiple RF sources                        based on power, distance, and frequency, irrespective of service                                    classifications

    B.  Clarifying the calculation or measurement methodologies to be used                         in cases where no exemptions apply to determine potential RF                                     exposure levels

    C. Addressing post-evaluation mitigation procedures like access, signage,                      and training to ensure that both the general public and trained                                    personnel are not exposed to RF emissions in excess of FCC limits

Under A, the FCC adopts three broad classes of exemptions:

  1. For extremely low-power devices that transmit at no more than 1 mW
  2. For somewhat higher-power devices with transmitting antennas that operate within 40 cm of the body, a formula based primarily on the localized specific absorption rate (SAR) limits derived from the frequency, power, and separation distance of an RF source
  3. For all other transmitters based on a set of formulas for the maximum permissible exposure (MPE) limits in five frequency bands

For each of those three classes, the FCC provides for both the single-transmitter and multiple transmitter cases. The multiple transmitter methodologies involve some complex formulas, which do not lend themselves to summarization here, but about which we are available to provide additional information.

Under B, the FCC states that for fixed RF sources that do not qualify for an exemption, a “determination of compliance” must be performed to ensure that RF exposure limits are not exceeded in places that are accessible to people. The FCC removes from its rules specific acceptable approaches for evaluating an RF environment and “will instead allow any valid computational method to be used in demonstrating compliance with [its] RF exposure limits.” The FCC adds that to ensure validity, computational modeling must “be supported by adequate documentation showing that the numerical method as implemented in the computational software has been fully validated.”

Under C, The FCC states that “the purpose of mitigation is to take the appropriate steps to keep persons out of [space where the RF exposure limits are exceeded].” and that mitigation measures include “labels, signs, markings, barriers, positive access controls, and occupational training.”


The new FCC rules will require licensees and operators of fixed RF sources to use signs when a single or multiple RF sources in an area create locations where exposure is above the limit for the general public; however, “indicators” such as chains, railing, paint, and diagrams may alternatively be used, “particularly in situations where positive access controls are in place to effectively restrict access only to persons who are trained…”

The FCC adopted four categories of signage:

  1. “INFORMATION” where RF exposure is less than the General Population limit
  2. “NOTICE” where RF exposure is above the General Population limit but below the Occupational limit
  3. “CAUTION” where RF exposure is between one and ten times the Occupational limit
  4. “WARNING” where the RF exposure is greater than ten times the Occupational limit.

Regardless of category, “DANGER” signs are required anywhere immediate and serious injury would occur on contact. Note that Category 1 signs are optional and voluntary.

Signs for all four categories must include an RF energy advisory symbol, a description of the RF source, a statement of the behavior necessary to avoid over-exposure, and up-to-date contact information for someone with authority and capability to provide a prompt response.

Category 2 areas not only require the NOTICE signs, but also require positive access controls. Category 3 areas require the CAUTION signs, positive access controls, and controls or indicators such as chains, railings, contrasting paint, or diagrams surrounding the area. Category 4 requires the same protections as Category 3 with this important FCC proviso: the only apparently adequate mitigation measure within the Category 4 area is power reduction that will bring exposure within the occupational limits. The FCC adds that accurate placement of signs is critical and should make clear both where limits are and are not exceeded. For “readability” requirements for signs, the FCC relies on the Occupational Safety and Health Administration (OSHA) requirements for accident prevention signage.


For application of the occupational/controlled limits, the FCC states that training is critical to ensure that exposed persons are aware of the potential for exposure and can exercise control over it. The FCC acknowledges, however, that it is difficult to prescribe clearly what constitutes appropriate training. Therefore, the FCC’s Office of Engineering and Technology (OET) is directed to coordinate with OSHA and provide guidance thereon as soon as practicable in a revised OET Bulletin 65.

Responding to concerns about licensee responsibility for mitigation at sites not completely under a licensee’s control, the FCC declined to establish a safe harbor from actions or events beyond the licensee’s control. Instead, the FCC decided that a licensee’s due diligence in ensuring compliance with the RF exposure requirements considering the totality of measures taken will be the test for a safe harbor. The FCC states that “responsibility for maintenance of the conditions that permit a siting within our rules can be an enforceable condition of a [site] lease.”

Where there are multiple licensees at a site, all licensees are responsible for compliance with the FCC RF exposure limits. However, if a licensee can demonstrate that its facility was compliant and did not cause non-compliance, it will not be liable in an enforcement proceeding.

To ease the transition to the new rules, the FCC establishes a two-year transition period from the effective date of the new rules to allow licensees and manufacturers the opportunity to determine whether they meet the criteria for exemption. The FCC also provides that equipment authorized prior to the effective date of the Second R&O can continue to be marketed and used under their existing authorization so long as parties deploying such equipment ensure that equipment is installed consistently with the information in the installation manual or user instructions.

Notice of Proposed Rulemaking (NPRM)

The FCC initiated a new NPRM to address the challenges of evolving technology. It proposes to expand the range of frequencies for which the RF exposure limits apply (currently 100kHz to 100 GHz) to a new upper limit of 3000 GHz; to reduce the spatial averaging area of the human body from the current 20 cm² to 1 cm² for higher frequencies; to establish a new “device-based time-averaging” and seeks comments on whether and how to apply it to ensure compliance with the RF exposure rules; to address wireless power transfer devices, which can operate at very high power; and how to regulate to ensure that RF energy therefrom does not exceed FCC exposure limits or create harmful interference to other services.

Memorandum Opinion and Order (MO&O)

In the MO&O part of this decision, the FCC disposed of issues resolved in its 2013 decisions that were the subject of petitions for reconsideration. No changes were made to those decisions on reconsideration.

This area of FCC regulation is important and complex. Radiofrequency exposure limits and mitigation requirements are an area of special expertise at Keller and Heckman LLP. With our wide-ranging and extensive experience in the areas of telecommunications and health and safety, we stand ready to assist you with any questions or concerns about these regulatory requirements.