AFOSHSTD48-9.pdf

Template modified: 27 May 1997 14:30

BY ORDER OF THE

SECRETARY OF THE AIR FORCE

AIR FORCE OCCUPATIONAL SAFETY AND

HEALTH STANDARD 48-9

1 AUGUST 1997

Aerospace Medicine

RADIO FREQUENCY RADIATION (RFR)

SAFETY PROGRAM

OPR: HQ AFMOA/SGOE

(Lt Col Don Jordan)

Certified by: HQ AFMOA/SG2 (Maj Gen Charles H. Roadman II)

Supersedes AFOSH Standard 161-9, 12 February 1987.

Pages: 69 Distribution: F

The criteria in this standard are the Air Force’s minimum occupational health requirements. A program is established in this standard to prevent possible harmful effects to personnel from exposure to potentially hazardous levels of RFR. This standard applies to all US Air Force organizations, including all US Air Force Reserve and Air National Guard on Federal Service. Major commands (MAJCOM), direct report-ing units (DRU), and field operating agencies (FOA) supplement this standard when additional or more stringent safety and health criteria are required refer to Air Force Instruction (AFI) 91-301, Air Force Occupational and Environmental Safey, Fire Protection and Health (AFOSH) Programs, for instructions processing supplements or variances. Report conflicts in guidance between this standard, federal stan-dards, or other directives through MAJCOM, DRU, or FOA surgeons to: HQ AF Medical Operating Agency (HQ AFMOA/SGOE), 110 Luke Avenue, Room 400, Bolling AFB DC 20332-7050.

This AFOSH Standard contains the same PELs used throughout industry as instructed by Department of Defense Instruction (DODI) 6055.11, Protection of DoD Personnel from Exposure to Radiofrequency Radiation and Military Exempt Lasers, February 21, 1995. It applies to all Air Force military and civilian personnel (including foreign nationals) and to all sources of RFR owned or operated by the US Air Force, or under Air Force control. The Permissible Exposure Limits (PELs) of this standard do not apply to patients who are undergoing diagnostic or therapeutic procedures when RFR application is specifically prescribed by a physician, e.g., diathermy during physical therapy treatments, electromagnetic imaging, etc. The PEL does, however, apply to patients who may be exposed incidentally during the medical pro-cedure. Control measures at least as stringent as those recommended by the DODI and the American National Standards Institute/Institute of Electrical and Electronics Engineers (ANSI/IEEE) C95.1-1991, IEEE Standard for Safety Levels with Respect to Human Exposure to Radio Frequency Electromagnetic

NOTICE: This publication is available digitally on the SAF/AAD WWW site at: http://afpubs.hq.af.mil.

If you lack access, contact your Publishing Distribution Office (PDO).

Fields, 3 kHz to 300 GHz, April 27, 1992, are implemented by this standard. Refer also to National Coun-cil on Radiation Protection and Measurements (NCRP) Publication No. 86, No. 119, and American Con-ference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Values (TLVs) Booklet for additional information on RFR. Technical assistance in applying this standard can be obtained by contact-ing the Armstrong Laboratory (AL/OERS) located at Brooks AFB, TX, DSN 240-3179 or (210) 536 3179.

SUMMARY OF REVISIONS

This document is substantially revised and must be completely reviewed.

Chapter 1— RESPONSIBILITIES 4

1.1. Secretary of the Air Force

1.2. Air Staff

1.3. HQ Air Force Materiel Command (AFMC)

1.4. Human Systems Center (HSC)

1.5. US Air Force in Europe (USAFE)

1.6. Major Commands (MAJCOM), Direct Reporting Units (DRU), and Field

1.7. Host Wing, Center, and (or) Division Commander

1.8. Medical Treatment Facility (MTF) Commander

1.9. Unit Commanders

1.10. Supervisor

1.11. Individual

Chapter 2— REQUIREMENTS 9

2.1. Permissible Exposure Limits (PELs)

2.2. PEL Averaging Periods

2.3. Controlled Environment PELs

Table 2.1. PELS for Controlled Environments

2.4. Uncontrolled Environment PELs

Table 2.2. PELS for Uncontrolled Environments

2.5. Induced Current Limits. (Section B of Tables 2.1 and 2.2)

2.6. Pulsed Peak Field Limits. (Section C of Tables 2.1 and 2.2)

2.7. Partial Body Exposure Limits. (Section D of Tables 2.1 and 2.2)

2.8. PELs and Exposure Guidance for High Power Microwave (HPM) and

Table 2.3. PELs for HPM and EMP Simulator Systems

2.9. Exclusions Rules for PELs

Chapter 3— BASE PROGRAM REQUIREMENTS 17

3.1. Risk Assessment

3.2. Recognition

3.3. Evaluation

3.4. Controls

Figure 3.1. RFR Hazard Warning Sign Format

3.5. Investigation of Alleged Exposures to RFR

3.6. Medical Surveillance Requirements

3.7. RFR Safety Awareness Training Requirements

Attachment 1— GLOSSARY OF TERMS 32

Attachment 2— ALLEGED RFR EXPOSURE INCIDENT INVESTIGATIONS

AND REPORTS 39

Attachment 3— THEORETICAL EVALUATION PROCEDURES 43

Attachment 4— ON-SITE INSPECTIONS AND MEASUREMENT SURVEYS 50

Attachment 5— INTRODUCTION TO RADIO FREQUENCY RADIATION

AND BIOEFFECTS 60

Attachment 6— RECOMMENDED MEDICAL SURVEILLANCE PROCEDURES 68

Chapter 1

RESPONSIBILITIES

1.1. Secretary of the Air Force.

1.1.1. Office of the Assistant Secretary (Acquisition)(SAF/AQ). Ensures that Air Force laboratories and Special Program Offices (SPOs) address the issues of health and safety early and throughout the Research, Developement, Test and Evaluation (RDT&E) cycle and obtains measured personnel haz-ard data for all emitters at the earliest possible time in the cycle for inclusion into applicable Technical Orders (TOs).

1.1.2. Deputy Assistant Secretary of the Air Force (Environment, Safety and Occupational Health)(SAF/MIQ). Provides oversight for all Air Force policy related to Environment, Safety and Occupational Health.

1.2. Air Staff. All Air Staff elements will ensure their activities are conducted in a manner consistent with the spirit and intent of this standard, the DODI 6055.11, and ANSI/IEEE C95.1-1991.

1.2.1. The Surgeon General (SG):

1.2.1.1. Establishes policy for the control of RFR in Air Force workplaces and environments.

1.2.1.2. Establishes RFR personnel exposure standards and criteria.

1.2.1.3. Acts as the approval authority for waivers of protection standards and control procedures.

1.2.2. Air Force Safety Center (HQ AFSC):

1.2.2.1. Establishes safety inspection standards for RFR safety programs to ensure compliance with this standard, subject to approval by HQ US Air Force/SG.

1.2.2.2. Implements policy and inspection standards for safety programs associated with the non-biological hazards of RFR-producing systems and equipment, e.g., electro-explosive ordinance detonation, accidental fuel vapor ignitions, and electromagnetic interference hazards.

1.2.3. Air Force Inspection Agency (HQ AFIA). Implements programs to assess or inspect compli-ance with the requirements contained in this standard.

1.3. HQ Air Force Materiel Command (AFMC).

1.3.1. Plans, programs, and budgets for research relating to the biological effects of RFR, the health and safety of RFR workers, and the protection of the general public. Addresses the issues of health and safety early and throughout the Research, Development, Test and Evaluation (RDT&E) cycle.

1.3.2. Develops and implements policy and procedures to ensure that required personnel hazard data for emitters is measured at the earliest possible time in the acquisition cycle and is made available to the appropriate agency.

1.3.3. Provides information to using commands concerning the adequacy of RFR hazard protective devices, materials, and engineering control measures.

1.4. Human Systems Center (HSC). The HSC will, through the:

RFR.

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1.4.1. Armstrong Laboratory, Occupational and Environmental Health Directorate, Radiofrequency Radiation Division (AL/OER, Brooks AFB):

• Provide research, consultation and assistance on the biological effects of RFR.

• Maintain information on ways to measure, evaluate, and control occupational exposures to

• Maintain technical expertise in RFR technology and new developments which may affect sa Air Force operations.

• Provide guidance to Bioenvironmental Engineers on the use and application of commercially able safety products. Such products include those designed to protect personnel from RF sure, to detect the presence of RFR fields, or to measure exposure levels.

• Assist the US Air Force Surgeon General’s office in establishing policy on the use and appl of safety devices on Air Force Installations.

• Maintain specialized measurement equipment necessary to monitor and record RFR em perform field measurements, and evaluate work environments for potential hazards to the and safety of Air Force employees and the general public.

• Conduct occupational health and environmental safety surveys of RFR facilities and emit identify areas in excess of the PEL, and to determine the type of control measures required.

• Send the Director, HQ Air Force Medical Operations Agency (AFMOA), USAFE, PACAF each MAJCOM copies of reports, studies, and other information relating to RFR safety.

• Work with other AFMC laboratories and other services to evaluate any unique or unusua safety issues.

• Help solve specific operational RFR problems.

• Recommend RFR personnel exposure limits to the HQ AFMOA.

• Maintain a repository containing the nominal characteristics of Air Force owned and operate emitters to assist installation level personnel with the inventory and identification of poten hazardous systems. Ultimately this repository should be made available via the world wide similar structure in order to facilitate use by customers.

• Maintain an official repository containing pertinent records of personnel overexposures tha found to be five times the PEL or greater.

• Provide consultation on RFR facilities evaluation, RFR exposure control, medical surveillanc biomedical research programs.

1.4.2. US Air Force School of Aerospace Medicine, Department of Bioenvironmental Engine (USAFSAM/BE) will:

• Provide formal training programs for medical personnel to ensure they are proficient in cond the necessary RFR hazard assessments and measurements, and are knowledgeable abo rent issues involving RFR and the known bioeffects associated with exposure.

• Work closely with the researchers and consultants located at AL/OER to ensure that inst provided to trainees is based on the most current applicable scientific findings, and in keepin the most current Air Force policies.

• Obtain guidance and assistance from AL/OER when developing RFR course curriculums to the accuracy and applicability of information conveyed to the students.

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1.4.3. Armstrong Laboratory, Aerospace Medicine Directorate, Clinical Sciences Division (AL/ AOC, Brooks AFB) will:

• Provide consultant examinations in ophthalmology and dermatology.

• Develop methods to evaluate occupational injuries resulting from exposures to RFR.

• Recommend medical surveillance requirements to HQ AFMOA/SGP.

1.5. US Air Force in Europe (USAFE). Through resources of 601 Med Squadron/SGB, gives ad and aid similar to that tasked to Armstrong Laboratory (AL/OER) (paragraph 1.4.1).

1.6. Major Commands (MAJCOM), Direct Reporting Units (DRU), and Field Operating Agen-cies (FOA).

1.6.1. Ensure operation and maintenance activities implement measures to prevent personn sure to RFR in excess of the limits prescribed in this standard.

1.6.2. Request specific RFR exposure criteria or standards not contained herein from HQ SGP, Director of Professional Services.

1.6.3. Contact AL/OER for guidance and assistance in resolving personnel RFR hazards.

1.7. Host Wing, Center, and (or) Division Commander. Host Wing, Center, and (or) Division Com mander will:

1.7.1. Through the Bioenvironmental Engineer (BEE), support integrated implementation o standard throughout the wing, center or division.

1.7.2. Support BE in their efforts to ensure compliance with this standard to ensure wing comp

1.7.3. Ensure implementation of this standard by government contractors through appropria curement action. Contracts should state who is responsible for occupational safety and health lance of the contract employees working on Air Force facilities with government equipm Whenever possible, new contracts should include compliance requirements of this AFOSH sta

1.8. Medical Treatment Facility (MTF) Commander. The Medical Treatment Facility (MTF) Com mander will The MTF commander’s responsibilities are carried out, through the appropriate age detailed in the following paragraphs:

1.8.1. Bioenvironmental Engineering Flight (BE) will:

• Maintain a proficient level of knowledge, training and experience in assessing RFR radiatio ards in the workplace, performing required measurements, and responding to health issue by workers, base residents, and the general public.

• Act as the central focal point and local expert on matters relating to RFR hazards and bio with the support and assistance of Armstrong Lab personnel.

• Be familiar with the requirements of this standard and application of the appropriate PELs in to run an effective health and safety program.

• Assist unit commanders and shop supervisors in the development of RFR safety awareness programs, particularly in the area of bioeffects, exposure incident reporting, and identificatio control of hazardous areas in the workplace.

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• Review and evaluate the adequacy of existing baseline survey data for each RFR environm the base.

• Evaluate all RFR emitters capable of producing levels in excess of the PELs for periods o that could result in personal overexposures. Document the hazard evaluation in the app facility case file.

• Conduct RFR health hazard evaluations when new systems, operations, or modifications o the workplace to include the following:

• Identify controlled environments where the limits in table 2.1 apply.

• Identify uncontrolled environments where the limits in table 2.2 apply.

• Establish restricted access to areas in controlled and uncontrolled environments which exc applicable PEL.

• Recommend engineering controls, posting requirements, and administrative controls as nec

• Evaluate all requests for personal protective equipment and warning devices and control i ance and use, where appropriate. Protective equipment should only be issued where eng controls are not feasible or appropriate.

• Advise local commanders, during contingency operations, regarding the potential for per injuries from RFR emissions during combat operations.

• Investigate all alleged or suspected overexposures according to the instructions in paragrap this standard. Complete the final report of investigation for submission according to attachm Notify and coordinate with Armstrong Laboratory, RFR Division, Sources and Measurem Branch (AL/OERS), as needed, and provide copies of the final documentation for evaluatio possible inclusion in the RFR Exposure Repository.

• Provide the MAJCOM BEE, AFMOA/SGPA, and AL/OERS initial notification of a suspec RFR exposure.

• Notify PH of any RFR incidents which may require investigation. Provide the PH office of th findings from investigations and the final exposure determination.

1.8.2. Public Health Flight (PH) will:

• Work closely with BE in investigating RFR incidents, and provide medical surveillance feed to BE.

• Prepare and distribute AF Form 190, Occupational Illness/Injury Report, and additional doc tation as appropriate for all incidents of alleged personnel overexposure to RFR as outlined 48-101, Aerospace Medicine Operations, and this standard.

• Coordinate investigations of suspected or known overexposures to personnel with the inst ground safety staff, provide a copy of the AF Form 190, and advise BE of medical diag results.

• Ensure medical follow-up examinations specified by the occupational medicine consultant AOC are conducted for persons identified as having been overexposed to RFR.

1.9. Unit Commanders. Unit commanders will:

1.9.1. Establish a unit RFR safety awareness training program.

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1.9.2. Ensure shop supervisors responsible for the operation of potentially hazardous RFR emitters develop a unit radiation safety awareness training plan to aide in the implementation of the unit train-ing program.

1.9.3. Establish procedures for workers to report suspected overexposures to the responsible supervi-sor, and to BE. Supports BE investigative efforts and reconstruction of exposure incidents. Ensure these procedures are incorporated into the unit safety awareness training plan.

1.10. Supervisor. The supervisor will:

1.10.1. Ensure workers under their supervision are aware of and follow the safety procedures outlined in this standard, equipment technical manuals, and unit safety awareness training program

1.10.2. Prepare an RFR safety awareness training plan to provide initial training for newcomers and refresher training for system operators, maintenance personnel, and other workers assigned to duties in controlled environments.

1.10.3. Ensure the safety awareness training plan includes the following items:

• Location of potentially hazardous emitters operated by the unit.

• Areas that could exceed the radiation levels in table 2.1.

• Control procedures necessary to avoid exposures in excess of the Permissible Exposur

(PEL).

• Actions to be taken in the event of a suspected or actual RFR overexposure.

• Overview of the bioeffects that result from overexposure to RFR.

1.10.4. Coordinate RFR survey and measurement activities with command and supervisory pe and ensure these individuals are kept informed of the status of all such activities, particularly investigations of suspected or actual overexposures.

1.10.5. Inform BE and request a risk assessment survey for each new RFR system prior to op Notify BE of any physical or operational changes that could increase the power density of th generated by the emitter.

1.10.6. Ensure work areas identified by the BEE as hazardous RFR areas are clearly posted.

1.10.7. Ensure proper corrective actions are accomplished according to AFI 91-301 wheneve assessment code is assigned to a hazardous RFR situation.

1.11. Individual.

1.11.1. Follows procedures for safe work given in this standard, equipment TOs, manuals, a OIs.

1.11.2. Follows procedures established by the supervisor to ensure safe working conditions.

1.11.3. Ensures required warning signs and safety devices are in place and functional before ning work.

1.11.4. Promptly reports any suspected overexposure and any unsafe work condition to his supervisor.

Chapter 2

REQUIREMENTS

2.1. Permissible Exposure Limits (PELs).

2.1.1. The PEL is that exposure value to which an individual may be exposed without exhibiting damaging biological effects. PELs are derived from the recommended exposure levels in ANSI/IEEE C95.1-1991, which serves as a consensus standard developed by representatives of industry, scientific communities, government agencies, and the public. These values have been based upon a whole-body specific absorption rate (SAR) of 0.4 watts per kilogram (W/kg), and incorporates a safety factor of 10 below a SAR of 4.0 W/kg, which is the threshold for the occurrence of potentially deleterious biolog-ical effects in humans.

2.1.2. PELs are expressed in terms of measurable field parameters as a convenient correlation to the SAR. These field parameters include root-mean-square (rms) electric field (E) and magnetic (H) field strengths, their squares, or the plane-wave equivalent power densities (S) associated with these fields, and peak electric field strengths. Induced and contact current limits that can be associated with expo-sures to such fields are also established.

2.1.2.1. Sections A in tables 2.1 and 2.2, refer to time-averaged exposure values obtained by spa-tially averaging S, or the mean squared E and H values, over an area equivalent to the vertical cross-section of the human body (projected area). In the case of partial-body exposure, or non-uniform fields, these PELs (Section A) may be exceeded, but must comply with the partial body exposure limits listed in Sections D, tables 2.1 and 2.2. The PELs may also be exceeded if it can be shown that the SAR limits described in paragraph 2.9.3 are not exceeded. This may be accom-plished through SAR calculations or measurements utilizing human tissue equivalent material.

Base level Bioenvironmental Engineers may contact the Armstrong Lab Consulting Function for guidance when evaluating exposure incidents to determine if the PEL may be exceeded. The PELs may not be exceeded under any circumstances for exposure cases involving the head, eyes or testes.

2.1.2.2. For near-field exposures at frequencies less than 300 MHz, the applicable PEL is given in terms of rms E or H values. For convenience, the PELs also may be expressed in terms of plane-wave-equivalent values as shown by the S values in parentheses for the E and H fields, respec-tively, at frequencies less than 100 MHz.

2.1.3. There are no special RFR exposure limits for pregnant females. Any RFR environment that is safe for the mother is also safe for the developing embryo or fetus.

2.1.4. No practice shall be adopted or operation conducted involving planned exposure of personnel to RFR levels in excess of the applicable PEL.

2.2. PEL Averaging Periods.

2.2.1. PELs in table 2.1, Section A, refer to values averaged over any 6-minute period for frequencies less than 15 GHz, and over shorter periods for higher frequencies (10 seconds at 300 GHz). The PELs in table 2.2, Section A refer to values generally averaged over any 6-minute or 30-minute period for frequencies less than 3 GHz. For certain frequency intervals, the averaging period will vary as a func-tion of frequency as shown in tables 2.1 and 2.2, Sections A.

es con-he levels rt B.

ations be sub-e areas here safe sure that an Air posure

2.2.2. For an exposure duration less than the averaging period, the maximum permissible exposure level, is PEL [Tavg/Texp], where Texp is the exposure duration in that interval expressed in the same time units as Tavg.

2.3. Controlled Environment PELs. The controlled environment PELs, given in table 2.1, are given as a function of frequency and were based on a SAR of 0.4 W/kg. These limits were developed to control human exposures to electromagnetic energy at radio frequencies ranging from 3 kHz to 300 GHz, and to limit the localized SAR occurring in the feet, ankles, wrists, and hands of personnel due to exposure to such fields or contact with objects exposed to such fields. PELs are given in terms of rms electric (E) and magnetic (H) field strengths, equivalent plane-wave free space power densities (S), and induced currents

(I) in the body. Controlled environment exposures include the following:

• Exposure that may be incurred by personnel who are aware of the potential for RFR exposur joined with their employment or duties.

• Exposure of other cognizant individuals.

• Exposure that is the incidental result of passage through such areas where analysis shows t may exceed those given in table 2.2, Part B, but do not exceed those values in table 2.1, Pa

For example, an administrative assistant who works in the administrative office of the communic squadron on the flightline, and is aware of the presence of RFR in the work environment, would ject to the Controlled Environment PELs of table 2.1. This individual should be made aware of th where RFR is present during the initial awareness training process, and should be advised as to w levels can be exceeded. Thus, the administrative assistant has accepted the potential risk of expo may be incurred during the performance of their normal duties. If the same individual lives near Force Radar facility, the residential environment occupied by the assistant and the individual’s ex while in the residential environment would be controlled by the PELs given in table 2.2.

Table 2.1. PELS for Controlled Environments.

Frequency Range(f) (MHz)

Electric Field (E) (V/m)

Magnetic Field (H (A/m)

Power Density(S) (mW/ cm2) (E,H)

Averaging Time (Tavg in min) (E, H, S)

A. RFR Fields.

0.003 - 0.1 614 163 (102, 106) 6

0.1 - 3.0 614 16.3/f (102, 104/f2,) 6

3 - 30 1842/f 16.3/f (900/f2, 104/f2, 6

30 - 100 61.4 16.3/f (1.0, 104/f2,) 6

100 - 300 61.4 0.163 1.0 6

300 - 3000 f/300 6

3000 - 15000 10 6

15000 - 300000 10 616000/f1.2

2.4. Uncontrolled Environment PELs. Uncontrolled environment exposures can occur in areas where individuals would have no knowledge or control of their exposure. These locations would include living quarters or workplaces where there are no expectations that the exposure levels may exceed those shown in table 2.2. In uncontrolled environments where individuals unfamiliar with the phenomenon of induced RFR currents may have access, precautions should be taken to limit induced currents to values not nor-mally perceptible to individuals, as well as prevent the possibility of RFR burns.

Table 2.2. PELS for Uncontrolled Environments.

Frequency Range (f)(MHz)

Maximum Current Through Both Feet (mA)

Maximum Current Through Each Foot (mA)

Current (mA)

B. RFR Induced and Contact Current Restrictions.

0.003 - 0.1 2000f 1000f 1000f

0.1-100 200 100 100

Frequency Range (f) (MHz)

Peak Electric Field (E) (kV/m)

Peak Power Density Pulse for Pulse Du-rations < 100 msec (mW/cm2)

C. Pulsed RFR Fields (apply only when there are less than 5 pulses within the averaging time).

0.1 - 300000 100 (PEL)(Tavg)/(5)(pulse width)

Frequency Range (f)

(MH2)

Peak Value of Mean Squared Field (V2/m2 or A2/m2)

Equivalent Power Density (mW/cm2)

D. Partial-Body Exposures.

0.1 - 300 < 20E2 or 20H2

300 - 6000 < 20

6000 - 96000 < 20(f/6000)0.25

96000 - 300000 40

Frequency Range(f) (MHz)

Electric Field (E) (V/m)

Magnetic Field (H) (A/m)

Power Density (S) (mW/ cm2) (E,H)

Averaging Time (Tavg in min) (E, S) (H)

A. RFR Fields.

0.003 - 0.1 614 163 (102, 106) 6 6

0.1 - 1.34 614 16.3/f (102, 104/f2) 6 6

1.34 - 3.0 823.8/f 16.3/f (180/f2, 104/f2) f2/0.3 6

3.0 - 30 823.8/f 16.3/f (180/f2, 104/f2) 30 6

30 - 100 27.5 158.3/f1.668 (0.2, 9.4x105/ f3.336)

30 0.0636f1.337

NOTE:

Measurements to determine adherence to the PEL shall be made at distances of at least 20 centimeters

(cm) or greater from any object.

2.5. Induced Current Limits. (Section B of Tables 2.1 and 2.2).

2.5.1. Guidance is provided for limiting the RFR induced currents (averaged over any 1 second) in the human body for free-standing conditions (no skin contact with metallic objects); and under condi-tions of grasping contact with metallic bodies to limit the maximum RFR current through an imped-ance equivalent to that of the human body.

2.5.2. The controlled environment induced body current limits will prevent localized SAR in the ankles or wrists from exceeding 20 W/kg. For uncontrolled environments, where individuals would not be aware of the existence of RFR currents, the values are set at levels that are not normally per-ceptble to individuals. In general, between 3 kHz and 100 kHz, the perception threshold is related to a tingling or prickling sensation; while between 100 kHz and 100 MHz, the perception threshold is related to a sensation of heat or warmth. Under some conditions, touching conductive objects in the

100 - 300 27.5 0.0729 0.2 30 30

300 - 3000 f/1500 30

3000 - 15000 f/1500 90000/f

15000 - 300000 10 616000/f1.2

Frequency Range (f) (MHz)

Maximu Current Through Both Feet (mA)

Maximum Current Through Each Foot (mA)

Current (mA)

B. RFR Induced and Contact Current Restrictions.

0.003 - 0.1 900f 450f 450f

0.1-100 90 45 45

Frequency Range (f) (MHz)

Peak Electric Field (E) (kV/m)

Peak Power Density Pulse for Pulse Du-rations < 100 msec (mW/cm2)

C. Pulsed RFR Fields (apply only when there are less than 5 pulses within the averaging time).

0.1 - 300000 100 (PEL)(Tavg)/(5)(pulse width)

Frequency Range (f) (MHz)

Peak Value of Mean Squared Field (V2/m2 or A2/m2)

Equivalent Power Density (mW/cm2)

D. Partial-Body Exposures.

0.1 - 300 < 20E2 or 20H2

300 - 6000 4

6000 - 96000 f/1500

96000 - 300000 20 vicinity of a radiating RFR antenna could result in a flow of RFR current of sufficient magnitude to be painful or that may produce a burn at the point of contact.

2.5.3. Evaluation of induced RFR currents will generally require a measurement to determine the RFR current flowing to ground through the feet of the individual, or the RFR current flowing through the hand in contact with a conductive surface. Measurement equipment required for these types of surveys is not generally available at base level. Paragraph 3.3.4 contains guidance on how to identify systems that may require further evaluation using induced and contact current measurement devices.

For systems generating frequencies between 0.003 and 100 MHz, contact AL/OERS, RFR Consulting Function for detailed guidance and measurement capabilities.

2.6. Pulsed Peak Field Limits. (Section C of Tables 2.1 and 2.2).

2.6.1. Peak power exposure limitations are provided for pulses in the frequency range of 0.1 to 300,000 MHz, where each pulse is less than 100 milliseconds (msec) and there are no more than 5 pulses in the time averaging period. Those limits are given to prevent unintentionally high exposure and to preclude high specific absorption for decreasingly short widths of pulses. If there are more than 5 pulses during any time period equal to the averaging time, or if the pulse durations are greater than 100 msec, the time-averaged S should not exceed the PELs given in Section A of tables 2.1 and 2.2.

2.6.2. For exposure to RFR pulses in the frequency range of 0.1 to 300,000 MHz, exposure is limited by either a peak (temporal) E field of 100 kV/m for each pulse or in terms of a peak power density value (S) for each single pulse, whichever is more limiting. For high frequencies and longer pulses, peak S will be more conservative.

2.6.3. The limitation on RFR fields under pulsed conditions, (less than 100 msec), means that the PEL as averaged over any 100 msec is reduced by a factor of five, and a maximum of five such pulses is permitted during any period equal to the averaging time. For example, in the microwave region for exposure to a single pulse, the specific absorption over any 6-minute period is limitd to 28.8 J/kg per pulse (spatial average) with a maximum of five such pulses (i.e., (5)(28.8 J/kg) = 144 J/kg), which is equivalent to a SAR of 0.4 W/kg over a 6-minute period).

2.7. Partial Body Exposure Limits. (Section D of Tables 2.1 and 2.2).

2.7.1. Implicit in the PEL definition of a whole-body averaged SAR of 0.4 W/kg for a controlled environment and 0.08 W/kg for an uncontrolled environment, is the assumption that spatial peak SARs may occur that exceed the whole-body averaged values by a factor of more than 20 times. The values provided in Section D of tables 2.1 and 2.2 allow for equating substantially non-uniform field exposure or partial-body exposure to an equivalent uniform field exposure. The BEE should consider the values given for partial body exposures when the exposure exceeds the PELs given in tables 2.1 or 2.2, and the exposure was limited to a specific part of the body, or the field was not uniformly distrib-uted over the whole body of the individual exposed.

2.7.2. For exposure of parts of the body, the spatially averaged PELs given in Section A of tables 2.1 and 2.2 may be relaxed provided the peak value of the mean squared field strength (E and H Fields) does not exceed 20 times the square of the allowed spatially averaged values at frequencies below 300 MHz, or the equivalent S levels do not exceed the levels shown in Section D. of tables 2.1 and 2.2 as averaged over the Tavg periods given for frequencies above 300 MHz. Those rules for relaxation of the limits for partial-body exposure do not apply for exposures to the eyes. The SAR exclusion rules in paragraph 2.7.1 can still be used to show conformance to the PEL, despite localized S values above the specified whole-body average. In such cases, exposures to the eyes are limited by the basic expo-sure criteria of a whole-body averaged SAR of 0.4 W/kg (controlled environment) or 0.08 W/kg (uncontrolled environment), and spatial peak SARs of 8 W/kg (controlled environment) or 1.6 W/kg (uncontrolled environment) as averaged over any one gram of tissue.

2.8. PELs and Exposure Guidance for High Power Microwave (HPM) and E l ec t r om a gne t i c Pulse (EMP) Simulators:

2.8.1. HPM Systems. For exposures in controlled environments involving HPM narrow-band sys-tems, the exposure limit for any single pulse or series of pulses lasting less than 10 seconds is provided in table 2.3. For uncontrolled environments, exposures shall conform with the PELs in table 2.2.

2.8.1.1. The exposure guidance given below in table 2.3 is based on HPM narrow-band systems operating within the following parameters: maximum pulse width of 10 microseconds, peak S of

0.1 to 10 kW/cm2, frequency greater than 100 MHz, repetition rate not greater than 10 pulses per second.

2.8.1.2. The exposure guidance is specific for HPM narrow-band systems and does not apply to exposure from EMP broad-band simulator systems. If the HPM system is not within those param-eters, then the PELs in table 2.1 apply.

2.8.1.3. For personnel exposure to HPM in a controlled environment, the measured fluence is not to exceed the values given in Section A of table 2.3 for any single pulse or series of multiple pulses lasting less than 10 seconds. The total fluence delivered over any 6-minute period shall not exceed the values in Section A of table 2.3. In all cases, the instantaneous E field shall not exceed 200 kV/m.

2.8.1.4. If the exposure values given in Section A of table 2.3 cannot be met, then the total mea-sured SA to the head shall not exceed 150 J/kg for any single pulse or 150 J/kg for multiple pulses in any 6-minute period.

2.8.2. EMP Simulator Systems. For exposure in controlled environments involving broad-band EMP simulators, the exposure limit is given in Section B of table 2.3. Measurements of EM Fields from broad-band EMP simulator systems require special instrumentation and techniques because of the inherent rapid rise time and the high field strengths associated with EMP. Contact Armstrong Labora-tory, Radiofrequency Radiation Division for measurement and evaluation assistance.

Table 2.3. PELs for HPM and EMP Simulator Systems.

Frequency Range (f) (MHz) Peak Electric Field (E) (kV/m) Maximum Fluence Level in Con-trolled ) Environments for Any Single Pulse or Series of Multiple Pulses Lasting Less Than 10 sec-onds Within Any 6-Minute Peri-od (J/cm2)

A. HPM (Narrow-Band Systems) 100 - 300 200 0.36

300 - 3000 200 3.6(f/3000)

2.9. Exclusions Rules for PELs.

2.9.1. The PEL values may be relaxed in the case of partial-body exposure, or by reference to the SAR exclusion rules, or the low-power device exclusion rules, as follows:

2.9.2. Partial-Body Exposure. In the case of partial-body exposure conditions from highly directional sources or from substantially non-uniform fields over an area equivalent to the body, relaxation of the PELs in tables 2.1 and 2.2, Sections A, is allowed for exposures limited to a portion of the body. Max-imum values for partial-body exposure limits are in Section D of tables 2.1 and 2.2. Partial-body lim-its do not apply in the case of direct exposure to the eyes.

2.9.3. SAR Exclusion Rule. The PELs in Sections A of tables 2.1 and 2.2 may be relaxed by refer-ence to SAR limits through calculations or measurements, as follows:

2.9.3.1. Controlled Environment Exclusion:

2.9.3.1.1. At frequencies between 3 kHz and 100 kHz, the PEL can be exceeded, if it can be shown that the peak rms current density as averaged over any 1 cm2 area of tissue and over 1 second does not exceed 0.035(f) mA/cm2 where f is in kHz.

2.9.3.1.2. At frequencies between 100 kHz and 6 GHz, the PEL may be exceeded if the expo-sure conditions can be shown to produce SARs below 0.4 W/kg as averaged over the whole body, and spatial peak SAR values not exceeding 8 W/kg as averaged over any one gram of tissue; except for the hands, wrists, feet, and ankles where the spatial peak SAR shall not exceed 20 W/kg as averaged over any 10 grams of tissue, and the induced body currents con-form with the values in Section B of table 2.1.

2.9.3.1.3. At frequencies above 6 GHz, where body absorption is quasi-optical and body res-onance considerations do not apply, the PELs may be relaxed using the time-averaged limits for partial-body exposures given in Section D of table 2.1.

2.9.4. Uncontrolled Environment Exclusion:

2.9.4.1. At frequencies between 3 kHz and 100 kHz, the PEL can be exceeded, if it can be shown that the peak rms current density as averaged over any 1 cm2 area of tissue and over 1 second does not exceed 0.0157(f) mA/cm2 where f is in kHz.

2.9.4.1.1. At frequencies between 100 kHz and 6 GHz, the PEL may be exceeded if the expo-sure conditions can be shown by techniques to produce SARs below 0.08 W/kg as averaged over the whole body, and spatial peak SARs not exceeding 1.6 W/kg as averaged over any one gram of tissue; except for the hands, wrists, feet, and ankles where the spatial peak SAR shall not exceed 4 W/kg as averaged over any 10 grams of tissue, and the induced body currents conform with the values in Section B of table 2.2.

>3000 200 3.6

Frequency Range (f) (MHz) Peak Electric Field (E) in Controlled Environments (kV/m)

B. EMP Simulators (Broad-Band Systems)

0.1 - 300000 100

2.9.4.1.2. At frequencies above 6 GHz, where body absorption is quasi-optical and body res-onance considerations do not apply, the PELs may be relaxed using the time-averaged limits for partial-body exposures given in Section D of table 2.2.

2.9.5. Low-Power Device Exclusion. At frequencies between 100 kHz and 1.5 GHz, the PELs given in tables 2.1 and 2.2 may be exceeded under the following conditions for devices in which the radiat-ing structure is not maintained within 2.5 cm of the body:

2.9.5.1. Controlled environment low-power device exclusion pertains to devices that emit RFR energy under the control of an aware user. That exclusion addresses exposure of the user.

2.9.5.1.1. At frequencies between 100 kHz and 450 MHz, the PEL may be exceeded if the radiated power is 7 watts, or less.

2.9.5.1.2. At frequencies between 450 and 1500 MHz, the PEL may be exceeded if the radi-ated power is (7)(450/f) watts, or less, where f is in MHz.

2.9.5.2. Uncontrolled environment low-power device exclusion pertains to devices that emit RFR energy without control or knowledge of the user.

2.9.5.2.1. At frequencies between 100 kHz and 450 MHz, the PEL may be exceeded if the radiated power is 1.4 watts, or less.

2.9.5.2.2. At frequencies between 450 and 1500 MHz, the PEL may be exceeded if the radi-ated power is (1.4)(450/f) watts or less, where f is in MHz.

2.9.5.3. At frequencies above 1500 MHz, engineering judgment should be used when granting a low power exclusion. For example, since the low power exclusion for controlled environments at 1500 MHz is 2 watts, a source of 15 GHz (10 times higher), with 20 mW (10 times lower) could also be excluded.

round at are Chapter 3

BASE PROGRAM REQUIREMENTS

3.1. Risk Assessment. The risk assessment process involves the recognition and evaluation of the poten-tial risk to human health. This chapter addresses the methodology for recognizing RFR hazards and for performing hazard evaluations for potentially hazardous systems. The requirements for the effective man-agement of an installation level RFR protection program are defined herein. Questions regarding the management or implementation of an installation program requirements should be referred to the RFR Radiation Division of Armstrong Laboratory, (AL/OERS) Brooks AFB TX 78235-5324, DSN 536-1182.

Assistance with electromagnetic compatibility testing or the assessment of risks associated with electro-explosive devices (EEDs) and fuel handling operations, must be referred to the 738 EIS/EEEX, 801 Van-denberg Avenue, Suite 201, Keesler AFB MS 39534-2634, DSN 597-3920.

3.2. Recognition. The recognition phase begins with baseline and annual industrial hygiene shop surveil-lance. All RFR transmitters owned and operated by avionics shops, communications facilities, industrial processes, and medical facilities should be identified during the regularly scheduled, on-site visits to these areas. The AF Form 2759, Radiofrequency Radiation Emitter Survey Data, should be completed at this time. Copies of this completed form for potentially hazardous emitters can be maintained separate of the cased files and used to develop a consolidated inventory. This can be a useful management tool for bases with large programs or unusual systems, but is not mandatory.

3.2.1. Risk Assessment Ratings. The final risk assessment rating should be assigned to each emitter upon completion of all phases of recognition and evaluation, but the process actually begins in the rec-ognition phase. Each system should be classified according to the hazard potential it presents, then rated according to the potential risk it represents. Examples of risk ratings are provided below with hazard potential categories discussed in paragraph 3.2.2:

3.2.1.1. Low Risk. A low risk indicates the system either is not capable of producing levels at or above the PEL (low-power excluded devices), or the transmission time is too short to exceed the average power density allowed for that frequency. For example, auto mounted or hand held radar guns used for traffic control would be classified as a low risk to users and the general public.

These devices cannot produce levels of energy at the PEL, so would be excluded from the inven-tory and assessment.

3.2.1.2. Moderate Risk. A moderate risk rating indicates the system is capable of producing power densities in excess of the PEL, but physical system controls are in place that would pre-clude exposure to personnel under normal operating conditions, test or maintenance procedures.

Examples of such controls would include the following:

• Safety interlocks that shut the system down if beam rotation is stopped.

• Elevation interlocks that turn off transmission when the angle of the beam is lowered to g accessible elevations.

• Dummy loaded systems, and emissions into RFR absorbers commonly called “hats”. th accessible from the ground.

vice as ry may informa-stimate ed on in the sibility ces, as from the thin 2.5 range ion). No radios, elimi-

NOTE:

A real world example of a moderate risk system is the typical TACAN antenna found on almost every fly-ing base. If the antenna rotation slows down at all from the design speed of 900 rpms, for any reason, the radiation emissions automatically shut down. Thus the system presents only a moderate risk of exposure to personnel because it can produce levels of energy above the PEL, but the interlock system must fail before any significant risk of exposure could reasonably be expected.

3.2.1.3. High Risk. A high risk rating is warranted for systems that can and do produce average power densities at or above the PELs, and these areas are accessible to personnel during normal operating conditions, or during routine test and maintenance procedures. Signs, rope barriers, cones or other control measures must be posted prior to transmitting with theses types of systems.

Examples of high risk systems include some nose mounted radar on small aircraft where the beam is accessible from the ground and routinely operated in a stationary mode for maintenance or test-ing while other maintenance personnel are working on or near the aircraft. Interlocks may reduce the hazard potential, but care should be exercised by the surveyor in ensuring these interlocks are not routinely bypassed as a part of normal operations.

3.2.1.4. The initial information gathered during the industrial hygiene survey is crucial to the evaluation process. Once the parameters for RFR emitters have been recorded, the next step is to determine which emitters are potentially hazardous to personnel. The major factor in determining the hazard potential of a particular emitter is based on accessibility of personnel. Hazardous areas that are well above ground level, or not normally accessible to personnel, are recorded as inacces-sible or climbing hazards (IH or CH) and are regarded as a lower survey priority. A detailed haz-ard assessment should then include the following processes:

• Review the operating parameters of the device and determine if the device is a low-power de described in paragraph 2.9.5.

• Review past surveys of the emitter or similar systems. Case files and Armstrong Laborato be able to provide some previous survey data.

• Review technical orders on the systems and look for parameters and other hazard distance tion.

• Perform a simple far-field calculation using the system parameters. This is a conservative e of the hazard distance, but is a very useful starting point in the pre-survey phase.

3.2.2. Emitter Hazard Potential. A description of the emitter hazard potential should be includ AF Form 2759 and maintained in the appropriate case file. Levels found at or above the PEL workplace, should be clearly defined in the case file, to include the hazard location and acces to personnel. One or more of the categories listed below should apply to each emitter:

3.2.2.1. Non-hazardous Emitters. RFR emitters that can be defined as low-power devi described in paragraph 2.9.5, are considered non-hazardous equipment, and are excluded PELs specified in tables 2.1 and 2.2 as long as the radiating structure is not maintained wi cm of the body. The criteria for low-power devices is based on a combination of frequency and radiated power of the system (see paragraphs 2.9.5.1 and 2.9.5.2 for detailed informat further evaluation or data collections are required for non-hazardous emitters. Hand-held cellular telephones, etc. usually fall into the non-hazardous category, but no system may be ls at or rally be e beam, (ECM) ing the cess of termine n if the tial for public ompared iority on

EL, but etermine se areas essment d prior-

EL, but normal that is d-held anual or trans-esult in are main-stems.

nated from the evaluation process if the radiating element is maintained within less than 2.5 cm from the body.

3.2.2.2. Potentially Hazardous Emitters. RFR emitters which do not fit the criteria for low-power devices (non-hazardous emitters), and are capable of producing levels at or in excess of the PELs given in tables 2.1 and 2.2, are considered potentially hazardous. However, the degree of hazard potential varies with environmental setting, duration of transmission, operator’s location, etc.

During the recognition phase each emitter should be reviewed to determine the necessity and pri-ority for performing further surveys and measurements during the evaluation phase. The use of hazard codes is no longer a requirement. Data on all potentially hazardous emitters must be main-tained in the appropriate facility case file. Include all unclassified operational parameters, hazard potential descriptions, and the location of fields found to be at or in excess of the PEL. These will include, but are not limited to, aircraft-mounted radar and electronic counter-measures (ECM) systems, some in-shop radar mockups, some ground-based radar systems, certain communications systems, some medical emitters, and all industrial emitters such as heat sealers.

• Ground-level Hazard Emitters. These are systems capable of producing power density leve above the PEL in areas accessible to personnel at or near ground level. This can gene determined by the location of the main beam above ground level, the size and shape of th and the angle of elevation. Many aircraft-mounted radar and electronic counter-measures systems will fall into this category. These types of systems should be the highest priority dur evaluation phase.

• Climbing Hazard Emitters. These transmitters are capable of producing levels of RFR in ex the PEL, but only in areas that require climbing. These emitters should be evaluated to de if, when, and where maintenance personnel may be required to climb into these areas. Eve maintenance procedures require shutdown with manual or automatic interlocks, the poten exposure may still exist if the controls are bypassed or failed. Exposure levels where the may have access to the main beam should be calculated during the evaluation phase and c to the PELs in table 2.2 to determine compliance. These systems should be the second pr the list of systems that require further evaluation.

• Inaccessible Emitters. These are systems capable of producing levels in excess of the P only in areas not normally accessible to personnel. These systems should be evaluated to d if maintenance procedures require entry into areas where the PEL could be exceeded. Tho where maintenance is performed should be included in the evaluation phase of the risk ass process, at least initially, and annually thereafter. These types of systems should be the thir ity on the list of systems that require further evaluation.

• Short Duration Emitters. These systems are capable of producing levels in excess of the P the transmission time is relatively short when compared to the PEL averaging time, under operating conditions. Thus, the transmission time is usually too short to result in an exposure likely to produce a SAR greater than 0.4 W/kg. These types of systems may include han radios, base stations, some airborne and ground communications systems that require m voice activation, etc. to transmit. Some automatic systems will transmit just long enough to re mit a message. On-time could vary, but will probably not exceed the duration necessary to r an exposure above the average PEL. Repair and maintenance shops where these systems tained should be a higher priority than routine operations when evaluating these types of sy rds.

ing the ntenna.

e oper-for the ce point result in trans-en esti-ds and mine if In some etical safety ting sys-propri-systems exclu-uted for l condi-e survey se file person-acces-uides, ensure

L, and hen no

3.3.