Boston University/ Boston Medical Center. Radiofrequency (RF) Safety Manual

Transcription

1 Boston University/ Boston Medical Center Radiofrequency (RF) Safety Manual

2 Contents 1. Statement of Commitment To Enviormental Health and Safety Purpose Definitions RF Safety Program Structure Radiation Safety Committee (RSC) Radiation Generating Devices Subcommittee (RGD) Radiofrequency Safety Officer (RFSO) Division of Medical Physics and Radiation Safety (DMPRS) Nonionizing Radiation (NIR) Worker Introduction to Radiofrequency radiation Hazards Health Hazards Exposure Limits Hazard Controls Engineering Controls RF Signage Administrative and Procedural Controls Personal Protective Equipment (PPE) Controlling RF shocks and Burns Training Emergencies and Incidents Appendicies BU-01 (Definitions): BU-02 (OEM/OHC Flipchart): Page 1

3 [BU/ BMC RADIOFREQUENCY SAFETY MANUAL] Rev. 1 : Statement of Commitment To Enviormental Health and Safety Page 2

4 2. Purpose Radiofrequency (henceforth to be stated as RF) Safety Manual provides guidance for safe access and awareness of RF emitting antennas located on Boston University and Boston Medical Center rooftops. This manual serves as comprehensive resource for all designated RF safety workers, and as guidelines for the general public users when accessing rooftops that contain RF emitting devices, and contains information on the structure, responsibilities, hazards for emergency response. 3. Definitions See appendix: BU-01 (Definitions) 4. RF Safety Program Structure Radiation Safety Committee, Radiation Generating Devices Subcomittee, RF Safety Officer, Division Medical Physics and Radiation Safety, have an important role in developing, improving and monitoring safe access of rooftops containing RF emitting devices at BU/BMC Radiation Safety Committee (RSC) The Radiation Safety Committee (RSC) oversees use of all radiation generating devices and radioisotopes at Boston University and Boston Medical Center. Radiation Safety Committee oversees the work of the Radiation Generating Devices Subcommittee Radiation Generating Devices Subcommittee (RGD) The BU/BMC Radiation Generating Devices Subcommittee (RGD) is responsible for continuing review of any pertinent RF issues that arise at the Boston University and Boston Medical Center. The RGD ensures that all RF related work is conducted in compliance with federal, state, and internal RF safety regulations and standards. The RGD meets quarterly to review any updates from the Radiofrequency Safety Officer. Page 3

5 4.3. Radiofrequency Safety Officer (RFSO) The Radiofrequency Safety Office (RFSO) operates out of the Environmental Health & Safety s Division of Medical Physics and Radiation Safety The responsibilities of the RFSO are listed below: a. Classifying or verifying classifications antennas (when applicable); b. Evaluating RF hazards; c. Determining adequacy of control measures; d. Recommending substitute or alternate controls; e. Performing, supervising and reviewing all rooftop RF surveys; f. Ensuring that survey equipment is calibrated according to manufacturer specifications; g. Approving the wording of area signs and equipment labels; h. Developing and overseeing administration of adequate RF safety training Division of Medical Physics and Radiation Safety (DMPRS) DMPRS provides services to assist in maintaining a comprehensive RF safety program. The responsibilities of the DMPRS are listed below: a. Oversight of purchasing new RF survey equipment; b. Providing RF safety training (in conjunction with staff located at Charles River Campus EHS); c. Assisting in RF incident investigation; d. Monitoring the implementation of the RF Safety Program; e. Providing support necessary to assist RF Safety Program; and f. Reviewing and maintaining relevant program documentation. Page 4

6 4.5. Nonionizing Radiation (NIR) Worker Each designated RF worker is responsible for: a. Complying with all requirements of the Boston University/ Boston Medical Center Radiofrequency Safety Program; b. Completion of the RF training; c. Utilizing appropriate PPE protection; d. Utilizing safe practices; and e. Notify the DMPRS if any issues are found when performing work on BU/BUMC rooftops. 5. Introduction to Radiofrequency radiation Radiofrequency (or RF) Radiation refers to the electromagnetic fields with frequencies between 300 khz and 300 MHz, often extending the lower-frequency boundar of RF radiation to 10kHz, or even to 3 khz in order to include emission from commonly used devices. Microwave (or MW) Radiation covers fields from 300 MHz to 300 GHz. Figure 1: The Electromagnetic Spectrum RF radiation is produced by devices such as radio and TV transmitters, induction heaters, and dielectric heaters (also known as RF sealers). MW radiation is produced by microwave ovens, parabolic (dish) antennas, and radar devices. For the purposes of this manual we will be grouping RF and MW radiation together under RF as they have similar characteristics and reactions in human tissue. RF is a type of non-ionizing radiation. Common sources of RF radiation are shown below in Table 1. Page 5

7 Source Frequency (MHz) Potential for Over-exposure? Video Display Terminal (VDT) No Dielectric Heater Yes (typically 27.12) Communications Transmitters: AM Radio Communications Transmitters: FM Radio Communications Transmitters: VHF TV Communications Transmitters: UHF Radio Communications Transmitters: Dish Antenna Yes Yes 54-72, 76-88, Yes Yes ,000 Yes CB Radio Yes Cordless Telephone No Cellular Telephone , 900, 1800, and 1900 No Traffic Radar 10,500 and 24,000 No Microwave Oven 915 and 2,450 No* *Federal legislation requires that microwave ovens be constructed to meet stringent microwave leakage limits and to have safety interlocks. When these interlocks are defeated, for example, during repair work, there is a risk of overexposure to microwave radiation. Table 1: Souorces of RF Radiation 6. Hazards 6.1. Health Hazards The nature and the degree of the health effects of overexposure to RF fields depend on the frequency and intensity of the fields, the duration of exposure, the distance from the source, any shielding that may be used, and other factors. The main effect of exposure to RF fields is heating of body tissues as energy from the fields is absorbed by the body. Prolonged exposure to strong RF fields may increase the body temperature, producing symptoms similar to those of physical activity. In extreme cases, or when exposed to other sources of heat at the same time, the body s cooling system may be unable to cope with the heat load, leading to heat exhaustion and heat stroke. Page 6

8 Localized heating, or hot spots, may lead to heat damage and burns to internal tissues. Hot spots can be caused by non-uniform fields, by reflection and refraction of RF fields inside the body, or by the interaction of the fields with metallic implants (e.g., cardiac pacemakers and aneurism clips). There is a higher risk of heat damage with organs which have poor temperature control, such as the lens of the eye and the testes. Note: There is currently no scientific studies or literature to support claims of nonthermal biological effects in humans due to RF exposures. Potential adverse affects can arrise in workers who have Pacemakers, metallic implants or other medical devices when exposed to an electromagnetic field in the RF/MW range. The response of the pacemaker or device is dependent upon the nature, frequency, and strenth of the RF signal, the proximity of the pacemaker to the source, and the design of the pacemaker(as it relates to the signal) including shielding, sensing and polarity. Pacemakers that incorporte a sensing funtion are susceptible to EM interference by frequencies that mimic cardiac signals. Other hazards include contact shocks and RF burns. These can result from the electric currents which flow between a conducting object and a person who comes into contact with it while they are exposed to RF fields. (These effects should not be confused with shocks from static electricity.) Some laboratory studies have reported biological effects from RF/MW radiation at field levels which are too low to cause tissue heating. To date, these non-thermal effects are not known to result in health hazards in workers. Although we are constantly exposed to weak RF fields from radio and television broadcasting, no health risks have been identified from this low-level exposure. Page 7

9 6.2. Exposure Limits Exposure limits for RF/MW radiation are designed to keep the RF/MW energy absorbed by the body well below the lowest levels associated with demonstrated adverse effects, and to reduce the likelihood of contact shocks and burns. Since the RF/MW energy absorbed by the body varies with the frequency of the fields, and since the rate of energy absorption is difficult to measure directly, the exposure limits are expressed in terms of frequency-dependent, mean-squared electric and magnetic field strengths, or in power density units (W/m 2 ). Power density measures the amount of radiating energy crossing a given area in a given period of time. Limits for exposure of the general public and occupational workers (also called Nonionizing Radiation Workers, or RF workers) are outlined in: 1. Massachusetts Department of Public health 105 CMR : Nonionizing Radiation Limits For: The General Public from Non-occupational exposure to electromagnetic fields, employees from occupational expsoure to electromagntic fields, and exposure from microwave ovens. 2. Federal Communications Commission Office of Engineering and Technology s OET Bulletin 65 (Edition 97-01) August 1997 Evaluating Compliance with FCC Guidelines for Human Exposure to Radiofrequency Electromagnetic Fields. Page 8

10 Per the Radiation Control program, occupational exposure of the whole body to RF fields (averaged over a 6 minute period) should not exceed the values in Table 2; and Public exposure of the whole body to RF fields (averaged over a 30 minute period) should not exceed the values in Table 3, below, where: f = frequency in megahertz (MHz) V = voltage in volts A = current in amperes m = length in meters cm 2 = area in square centimeters mw = power in milliwatts (E) 2 Maximum allowed Mean Squared (H) 2 Maximum allowed wave Mean Squared Maximum allowed Equivalent, Plane Wave, Free Space Frequency Range Electric Field Strength (V/m) 2 Magnetic Field Strength (A/m) 2 Power Density (mw/cm 2 ) 10 khz - 3 MHz 400, MHz - 30 MHz 4,000 (900/f 2 ) (900/f 2 ) 900/f 2 30 MHz MHz 4, MHz MHz 4,000 (f/300) (f/300) f/ MHz GHz 20, Table 2: Occupational RF Exposure limits for Employees Page 9

11 (E) 2 Maximum allowed Mean Squared (H) 2 Maximum allowed wave Mean Squared Maximum allowed Equivalent, Plane Wave, Free Space Frequency Range 10 khz - 3 MHz 3 MHz - 30 MHz 30 MHz MHz 300 MHz MHz 1500 MHz GHz Electric Field Strength (V/m) 2 Magnetic Field Strength (A/m) 2 Power Density (mw/cm 2 ) 80, (900/f 2 ) (900/f 2 ) 180/f (f/300) (f/300) f/1500 4, Table 3: Non- Occupational RF Exposure limits for the General Public Per the DPH 105 CMR , all areas where workers may be present that exceed the levels listed under Table 3, shall be marked with Danger- Pacemaker signage (see 7.1.1) as potential EM interactions caused by RF/MW radiation may occur. 7. Hazard Controls 7.1. Engineering Controls 1. Sources of RF radiation should be properly shielded to minimize stray radiation; 2. Devices which can produce acute thermal injuries (e.g., industrial microwave ovens) should have interlocked doors. These devices are not typically found in a rooftop emitter environment; 3. Devices which produce high levels of stray RF radiation (e.g., induction heaters) should be operated remotely; and 4. Antennas that will routinely exceed the occupational standards should be placed in locations least likely to be encounterd by common foot traffic (e.g., cell relays mounted on the exterior face of the upper floor of a building) RF Signage The purposes of RF Warning and RF Caution signs are to identify potential safety hazards before entering the rooftop environment. Particular attention should be used with placement of signage as it must be conspicuously displayed. Personnel who may need to Page 10

12 enter areas where RF emitters are being utilized, must be provided appropriate instructions and explanation of these warning signs RF Signage Placement RF Safety program exposure categories follow the IEEE and Massachusetts regulations. At Boston University, 4 categories will be defined and are shown below in Table 4: RF Safety Category Exposure Condition Operational characteristics of source(s) would not cause the action level to be exceeded. Operations characteristics of source(s) could cause the action level to be exceeded but would not casue the exposure limit to be exceeded in accessible areas. Potential to exceed the exposure limit in accessible areas, if mitigating controls are not applied. Exposure will exceed exposure limit in accessible areas. Occupational Action Level Public Action Level Below 2% Below 10% 2% 10% 20% 100% 100% 500% Table 4: Summary of RF Safety Categories based on RF exposure conditions Control Actions required None, unless changes in equipment since last survey alter category. RF Notice Signage posted. RF Caution and Pacemaker Danger Signage posted, RF safety training required, and control to access area is restricted. RF Warning and Pacemaker Danger Signage posted, RF safety training required, Nardalert XT required, and control to access area is restricted. Page 11

13 The appropriate signage for each of the action levels described in Table 4 is depicted below in Figure 2: Figure 2: Graphical representation of RF Saftey categorization process corresponding to categories 1-4 of Table 4. Page 12

14 For areas of exposure where limits exceed specific action limits, then appropriate signage will be required, as defined below: Notice Signage for Occupational Exposure exeeding 10% of the Public limit, or 2% of the Occupational Exposure (Category 2). Page 13

15 Caution Signage for Occupational Exposure exeeding 100% of the Public limit, 20% Occupational Exposure (Category 3). Page 14

16 Warning Signage for Occupational Exposure exceeding 100% of the Occupational Exposure limit. (Category 4) Page 15

17 For areas of occupational exposure where limits exceed public action limits (RF Safety Category 2), Pacemaker Danger signage will be required, as defined below: Danger Signage for pacemaker RF exposure hazard For any additional signage, or areas that require specific instructions, signs will be posted as appropriate. See Example Below: Sign for Upper roof Access to BU Law Tower. Page 16

18 7.2. Administrative and Procedural Controls Where hazards cannot be completely avoided through engineering controls, administrative controls are implemented to marginalize or remove the hazardous environment. In general, these controls consist of policies and work practices that will be instituted by BU/ BMC at an administrative level to ensure a safe working environment. Since there is significant dependence on human interaction with administrative controls, there will be extensive oversight and review involved to ensure safety and compliance. 1. Exposure of workers to RF radiation should not exceed the recommended exposure limits. 2. Areas where worker exposure to RF radiation is suspected to exceed the recommended limits must be surveyed to determine the exposure levels, and precaustions shall be made to ensure this area is not accessible to the public. 3. Needless exposure to RF fields should be avoided. 4. Exposure times should be kept as short as reasonably possible. 5. Any workers that have pacemakers, metal implants, or other medical devices will be required to obtain medical authorization from a physician knowledgeable in radiofrequency interference with the particular medical device prior to being allowed to enter areas posted as RF safety Categories 3 or 4 (Caution and Warning). 6. Potentially hazardous RF devices should be appropriately labeled, and areas of excessive exposure around them clearly demarcated. Where required notices with warnings and the necessary precautions shall be posted. 7. Electrically-activated explosive devices must not be placed near sources of RF radiation. 8. RF devices should not be used in flammable or explosive atmospheres unless deemed intrinsically safe by the manufacturer. 9. Equipment sensitive to RF radiation, such as telephone switchboards or control panels, should not be installed near sources of RF radiation. 10. When exposures cannot be reduced by the above methods, the RF device should be disabled for maintenance/work to be performed (e.g., WBUR antenna on Law Tower) Page 17

19 11. Maintenance of devices used to produce RF radiation should be done by qualified personnel following standard safety procedures. The equipment should be turned off whenever possible Personal Protective Equipment (PPE) When engineering and administrative controls cannot completley remove a hazardous enviornment, personal protective equipment must be utilized. If the emitter is not capable of being turned off, or is utilized under intermittent operation that cannot be locally controlled, then full RF protective suits including head and eye protection should be used. RF suits will not be issued by the institution and should be vendor sourced. Suits should be tested to ensure that they reduce worker exposure to levels below the occupational exposure limits and that they do not pose any safety hazards (e.g., overheating, shocks, or fire). In addition, personnel performing RF surveys on rooftops, should be wearing rubber-soled heeled footwear, so as to prevent slippage when climbing up or down ladders or incidental electrical shock Controlling RF shocks and Burns Personnel working around active RF emitters can utilize certain methods to mitigate the potential for shocks or burns. 1. Minimize contact with external surfaces of radiating devices. 2. Metallic structures producing contact shocks should be electrically grounded and/or insulated. 3. Insulating platforms or shoes (e.g., rubber-soled shoes) can be used to reduce energy absorption and currents to ground. 4. When the above measures are ineffective or not reasonably possible, workers should wear insulating gloves. Page 18

20 7.4. Training All individual workers who will have access to roof top enviornments, or otherwise be issued a TGM, ME, or 3533 key should take the RF safety training so that accurate assements of risks and hazard signage evaluations can be made where applicable. If individual workers are anticipated to enter areas where RF exposure exceeds RF safety level 3, as shown in Table 4, training is a required Control Action. An online module consisting of a presentation and an exam that must be passed with minimum 80% correct answers must be taken by all workers classified under the RF Occupational category. This training module is located online at the following web address: 8. Emergencies and Incidents During an emergency please follow applicable BU/BMC emergency procedures as detailed on posted Emergency Flip Charts. See appendix BU-02 (OEM/OHC Flip Chart). 1. Remove worker from exposure area to a cool environment and provide cool drinking water. 2. Apply cold water or ice to burned areas. 3. Seek immediate medical attention. 4. Severe MW or RF overexposure may damage internal tissues without apparent skin injury, so a follow-up physical examination is advisable. Page 19

21 References CMR , Massachussetts Department of Public Health, Nonionizing Radiation Limits For: The General Public from Non-occupational exposure to electromagnetic fields, employees from occupational expsoure to electromagntic fields, and esposure from microwave ovens. 2. OET Bulletin 65 (Edition 97-01) August 1997, Federal Communications Commission Office of Engineering and Technology, Evaluating Compliance with FCC Guidelines for Human Exposure to Radiofrequency Electromagnetic Fields. 3. C95.1, IEEE International Committee on Electromagnetic Safety (SCC39), IEEE Standard for Safety Levels with Respect to Human Exposure to Radio Frequency Electromagnetic Fields, 3 khz to 300 GHz 4. C95.3, IEEE International Committee on Electromagnetic Safety (SCC28), IEEE Recommended Practice for Measurements and Computations of Radio Frequency Electromagnetic Fields With Respect to Human Exposure to Such Fields, 100 khz 300 GHz 5. C95.6, IEEE International Committee on Electromagnetic Safety (SCC28), IEEE Standard for Safety Levels with Respect to Human Exposure to Electromagnetic Fields, 0 3 khz 6. C95.7, IEEE International Committee on Electromagnetic Safety (SCC28), IEEE Recommended Practice for Radio Frequency Safety Programs, 3 khz to 300 GHz Page 20

22 BU-01 (Definitions): Appendicies Accessible to the Public: areas not under the control of owner or operator of the facility. Department: the Massachusetts Department of Public Health. Employer: any person, firm, organization or other legal entity having the control or right to control a source of electromagnetic radiation, including but not limited to proprietor, lessee, and/or bailee. Exposure: occurs whenever and wherever an individual is subjected to electric, magnetic, or electromagnetic fields, taking into account both level of field strength and length of time. External surface: the outside surface of the cabinet or enclosure provided as part of the RF machine source, including doors, door handles, latches, and control knobs. Facility: any location in which one or more radiofrequency machine(s) is (are) located, and which is owned, controlled, or maintained by the same person. In the case where a structure has multiple sources, each person who owns, controls, or maintains a radiofrequency machine or machines shall be considered to have a separate facility at that same site. FCC: Federal Communications Commission. Hertz: unit of frequency equal to one cycle per second. Individual: any human being. Intermittent Operation: an operation where the radiofrequency machine does not normally continually operate for a period of 30 minutes or more at one time and generally the transmitter operation is random in time. Machine: a machine that emits radiofrequency (RF) electromagnetic radiation during operation. Microwave Oven: a commercially manufactured oven which is designed to heat, cook, or dry food through the application of radiofrequency electromagnetic radiation, and which is designed to operate at a frequency of 915 MHz and/or 2450 MHz. Nonionizing Radiation (NIR): the electromagnetic fields or energy in space for frequencies of the electromagnetic spectrum from ten kilohertz (khz) to 100 Gigahertz (GHz). The measures of such "radiation", electromagnetic fields or energy are power flux (milliwatts per square centimeter), or mean-squared-electric-field (E)2,(V/m)2 or mean-squared-magnetic- field (H)2, (A/m)2. In some cases only (E)2 or (H)2 is applicable (e.g., certain near fields or fields at low frequency) and in other cases (e.g., the microwave far-field conditions) the power flux is more applicable. Even where only the measures of either (E)2 or (H)2 is of concern, it has become Page 21

23 customary to express the field quantities in terms of equivalent (far-field, plane-wave) power densities. NIR is used interchangeably with the terms "RF radiation", "electromagnetic radiation" or "electromagnetic energy". Nonionizing Radiation (NIR) Worker: an individual who has been informed by his or her employer that activities in connection with their employment potentially involve access to areas exposed to radiofrequency radiation resulting from operation of a machine at the Place of Employment, where the exposure may exceed that allowed by 105 CMR Person: any individual, entity, corporation, partnership, firm, association, trust, estate, public or private institution, group, agency, political subdivision of this state, and other state or political subdivision or agency thereof, and any legal successor, representative agent or agency of the foregoing. Place of Employment: every place, whether indoors, or outdoors, or underground, and the areas appurtenant thereto, into, in or upon which any employee goes, or remains, either temporarily or regularly, in order to perform required duties in the course of his or her employment. Public or Member of the Public: all members of society, including the unborn. As used in 105 CMR , it does not include employees of a facility who have been informed that their employment potentially involves being exposed to electromagnetic radiation. Radiating Device: the antenna, leakage port or other part of a radiofrequency machine which emits radiofrequency electromagnetic radiation, excluding: (1) those machines radiating at frequencies between 300 khz and 100 GHz for which the effective radiating power is seven watts or less; (2) machine components which are not in themselves capable of, or designed for, radiation of an RF field; and (3) the signal generation portion of automatic or other test equipment designed to deliver a signal stimulus using coaxial or shielded cables to a device being tested. Radiation Control Program: the Radiation Control Program of the Massachusetts Department of Public Health. Radiofrequency (RF): in the frequency range of 10 kilohertz (khz) to 100 gigahertz (GHz). Radiofrequency Exposure Limits: the non-occupational limits for the general public to electromagnetic radiation in terms of the mean squared electric (E) 2 and magnetic (H) 2 field strengths or in terms of the equivalent plane wave free-space power density (when applicable), as a function of frequency, as given in Table 1, 105 CMR and the occupational limits for employees, as given exposures in Table 1, 105 CMR Page 22

24 Radiofrequency (RF) Site: a fixed structure whose sole purpose is to provide a location for RF facilities. Radiofrequency (RF) Heater and RF Sealer: devices operating between 300 khz and 300 MHz used to heat, melt or cure materials such as plastic, rubber, or glue by subjecting the material to a RF energy field. Included in this category are dielectric and induction heating devices. Radiofrequency Machine: any fixed device, machine, equipment or installation which is capable of generating a radiofrequency electromagnetic field. RF Safety Officer: refers to a person who by virtue of training or experience has acquired knowledge or instruction in RF electromagnetic fields and their measurement. The individual designated may be the Facility owner, an employee, or an agent hired by the employer. Survey: the measurement, by appropriate instrumentation, of the level of potential occupational RF radiation exposure incidental to the use of a machine. Watt: The unit of power or radiant flux. 1 Watt = 1 Joule/ second. Page 23

25 BU-02 (OEM/OHC Flipchart): In the event of an RF exposure, the employee or their supervisor should contact the RFSO. In case of Major medical emergencies, immediately contact: Medical Campus: call or have a co-worker call the Control Center at Charles River Campus: call or have a co-worker call BU Police at You will be referred to or transported to the appropriate health care location by the emergency response team. ROHP HEALTHCARE REFERRAL LOCATIONS AND TIMES LOCATION Medical Campus REGULAR WORKDAY HOURS BMC OEM 850 Harrison Avenue Yawkey, ACC (Mon-Fri 7:30 am to 4:00 pm) AFTER HOURS AND WEEKENDS BMC Emergency Dept. 751 Albany Street Charles River Campus BU Occupational Health Center (OHC) 930 Comm. Ave., West (Pleasant Street entrance) (Mon-Fri 9:00 am to 5:00 pm) BMC Emergency Dept. 751 Albany Street Page 24