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 Spectrum Management and Telecommunications
Radiocom
Antenna Structures
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Health Canada and Industry Canada FAQ on Radio Frequency FieldsFrequently Asked QuestionsCompiled by Industry Canada The following FAQ has been jointly developed by Health Canada and Industry Canada in order to address various questions related to radio frequency exposure to the general public. Health Canada is responsible for research and investigation to determine and promulgate the health protection limits for exposure to RF electromagnetic radiation. Accordingly, Health Canada has developed a guideline entitled "Limits of Human Exposure to Radiofrequency Electromagnetic Fields in the Frequency Range from 3 kHz to 300 GHz - Safety Code 6". As the regulator of radiocommunication and broadcasting installations and apparatus, Industry Canada has adopted Safety Code 6 for the protection of the general public. As such, Industry Canada requires all proponents and operators to ensure that their installations and apparatus comply with Safety Code 6 at all times.
Biological Effects Associated with
RF Exposure
Establishing RF Exposure
Limits
Industry Canada's Role in
Protecting the General Public from RF Exposure
For Further Information
Radio Frequency (RF) Energy(1) What is RF energy?Radio frequency (RF) energy is one form of electromagnetic energy that is a component of the electromagnetic spectrum. It includes microwaves, visible light and X-rays. RF energy, sometimes called "RF emissions", "RF waves" or "RF fields", is generated when a source current is fed to an antenna. This current excites electrons within the antenna and the energy propagates away from it in the form of an electromagnetic wave. Radio frequency fields have electric and magnetic components and the strength of the RF fields can be described by each component. The units "volts per metre" (V/m) and "amperes per metre" (A/m) are used to express the "electric" and "magnetic" field strengths respectively. Another common way to describe the RF field strength is by power density or the power per unit area, i.e. "watts per squared metre" (W/m2). (2) Why is RF energy important and what are the benefits?Probably the most important use for RF energy is in providing radiocommunication services to the public, industry and government. Radio and television broadcasting, cellular telephones, radio communications for emergency services, weather radar and satellite communications are examples of important applications. Non-radio uses of RF energy include industrial heating, microwave ovens, and medical devices, just to name a few. (3) What can I find at radiocommunication and broadcasting installations?At radiocommunication and broadcasting installations, you will generally find transmitters, transmission lines, antennas and their supporting structures. Radiocommunication and broadcasting transmitters are electronic devices that generate radio frequency (RF) signals which carry the information intended for receivers. The signals are transmitted by antennas, and after propagating through space, are picked up by receivers (via receive antennas) which then extract the information carried, be it a cell phone conversation, or a TV show. Antennas are the apparatus which transmit the RF energy. They are often located on top of a tower or other supporting structure. Occasionally a tower will be used as an antenna, but rarely and only with certain services such as AM broadcasting. As RF energy propagates away from the transmitting antenna, the RF power density (power per unit area, another way of expressing the RF signal strength, see Question #1) decreases very rapidly. RF Exposure Limits in Safety Code 6(4) How is the general public protected from overexposure to RF fields?To protect the general public, Health Canada has developed a safety guideline entitled "Limits of Human Exposure to Radiofrequency Electromagnetic Fields in the Frequency Range from 3 kHz to 300 GHz" which is commonly referred as Safety Code 6. This document has been adopted by many organizations across Canada and referred to in a number of regulations. Industry Canada has adopted Safety Code 6 for the protection of the general public. (5) What level of RF exposure is considered safe?If exposures do not exceed the limits specified in Safety Code 6, then there is no convincing scientific evidence that any adverse health effects will occur. (6) What is time averaging and how does it apply to exposure?Safety Code 6 and most other RF exposure standards specify "time-averaged" maximum exposure limits. The purpose is to smooth out the short-term highs and lows of the exposure intensity to arrive at an "average" with which to compare to the limit. The averaging time is the time period over which exposure is averaged. The averaging time should not be interpreted as the maximum allowable exposure time. In Safety Code 6, it is permissible to exceed the recommended exposure limits for short periods of time as long as the average exposure over the averaging time (0.1 hour or 6 minutes) does not exceed the limit. (7) Are the exposure limits specified in Safety Code 6 radio frequency dependent? If yes, why?Yes, the exposure limits specified in Safety Code 6 vary with radiofrequency in a way which reflects the different absorption characteristics of the human body at various frequencies. For example, the most restrictive limits are in the 30-300 MHz frequency range where the energy absorbed in the whole body from the incident wave energy is the highest. Biological Effects Associated with RF Exposure(8) What biological effects are associated with exposure to RF fields?The biological effects from laboratory studies reported in scientific peer-reviewed literature include those related to changes in temperature, blood brain barrier, melatonin, calcium efflux, DNA damage and gene expression. However, not all these biological effects have been established or are considered as health effects. For example, blood brain barrier and melatonin effects have not been consistently replicated. Studies on DNA strand breaks have also failed numerous independent attempts at confirmation, and calcium efflux changes are considered to be more of a biological response than an adverse health effect. A number of laboratory studies have looked into whether RF fields can cause cancer initiation and promotion. The overwhelming majority of these studies have found no evidence that RF fields damage DNA and are unlikely to act as initiators or promoters of carcinogenesis. (9) Which biological effects associated with RF exposure are considered "established effects"?The acceptance of an "established effect" is based upon peer-reviewed scientific reports, where the effect is demonstrated to be reproducible (in more than one laboratory), consistent (within the same laboratory and across other laboratories) and causal (due to the exposure agent). While a number of articles in the scientific literature report RF field bio-effects within a study, these effects do not necessarily stand up to scientific rigour as they are often not reproducible within the same (or other) laboratories or are subsequently found to arise as a result of confounding factors such as sample/tissue heating or vibration. See Question 17 for additional relevant information. (10) What is the difference between a biological effect and a health effect?A biological effect occurs when a change can be measured in a biological system after an introduction of some type of stimuli (e.g. RF energy). However, the observation of a biological effect, in and of itself, does not necessarily suggest the existence of a health effect. A biological effect only becomes a health hazard when it causes detectable impairment of health. According to the World Health Organization, health is "a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity." (11) What is an epidemiological study? Are there any epidemiological studies of RF exposure?An epidemiological study is a statistical study on human populations, which attempts to link human health effects to a specified cause (e.g. RF energy). There have been numerous epidemiological studies on RF exposure and the incidence of cancer in humans. The majority of these studies have failed to find any association between such exposures and any adverse heath effects (e.g. cancer). (12) What is signal modulation? Do different types of modulation change RF biological effects?Signal modulation is a process whereby certain characteristics of a radio wave are varied with transmitted information (voice, pictures and data). Different signal modulations in both analogue (e.g. AM, FM) and digital (numeric) formats have been used in radiocommunication. While most radio technologies have used analogue signals, modern wireless telecommunications are using digital transmissions. Detailed scientific reviews conducted so far have not revealed any hazard specific to different RF modulations. (13) What is electromagnetic hypersensitivity?Electromagnetic hypersensitivity (EHS) is a condition in which a person reports physical and/or psychological symptoms, which appear to be aggravated by electric and/or magnetic fields at exposure levels tolerated by the general public. The symptoms most commonly experienced include dermatological symptoms (redness, tingling, and burning sensations) as well as neurasthenic and vegetative symptoms (fatigue, tiredness, concentration difficulties, dizziness, nausea, heart palpitation, and digestive disturbances). The collection of symptoms is not part of any recognized syndrome. While EHS symptoms are real, studies to date suggest that they are not related to actual exposures to electric or magnetic fields. Electromagnetically hypersensitive individuals are no better than non-hypersensitive individuals in detecting the presence of these fields. Further information on EHS is available on the WHO website at: http://www.who.int/mediacentre/factsheets/fs296/en/index.html Establishing RF Exposure Limits(14) How were the Safety Code 6 exposure limits established?The limits specified in Safety Code 6 were established from the results of hundreds of studies over the past several decades where the effects of RF energy on biological organisms were examined. These limits are similar to other national and international standards that are based on established effects. All recognized standard-setting bodies use the same scientific data and a similar general approach to develop safety guidelines. Differences in interpreting the biological effects under certain exposure conditions sometimes result in small differences in the exposure limits that are recommended. These differences will not affect a person's health. Canada's exposure limits are among the most stringent guidelines that are based on established effects. (15) What scientific studies support the exposure limits outlined in Safety Code 6?Safety Code 6 is based on peer-reviewed literature from reputable scientific journals, whose peer-review panels are experts in this subject area. Information published in non peer-reviewed journals or anecdotal reports posted on the Internet carry much less weight because it is difficult to evaluate the quality of the work. It should also be emphasized that no single study is used as a basis for establishing the limits in the Code, but rather the bulk of scientific evidence contained in the literature. It is well known that even amongst the body of peer-reviewed literature, there is a range of quality and therefore each manuscript must be judged on its own merits. (16) Does Safety Code 6 take into account the possible non-thermal effects associated with exposure to RF fields?Safety Code 6 takes into account all biological effects whether they are related to heating of the tissue (thermal) or exposure levels too low to cause significant tissue heating (non-thermal). The understanding that the limits specified in the Code are based entirely on thermal effects is incorrect. For frequencies from 3 kHz to 100 kHz, the biological endpoint on which the limits are based is nerve and muscle stimulation. Although these are acute effects, they are non-thermal in nature. At higher frequencies, non-thermal effects are not well established and currently do not form a scientifically acceptable basis for restricting human exposure to RF fields. There is no convincing scientific evidence that RF exposures have any link to cancer initiation or promotion. The body of peer-reviewed literature in this area overwhelmingly demonstrates a lack of linkage, and where the few reports of linkage effects were found, some may be attributed to factors other than RF energy. (17) Is Safety Code 6 up-to-date? How often is the guideline revised?Health Canada continuously conducts its own research, and reviews new research findings published in peer-reviewed literature as they become available. During the review, if sufficient evidence becomes apparent, a revision process will be initiated for Safety Code 6. At this time, Health Canada is awaiting the outcome of the International Agency for Research on Cancer (IARC) multi-country INTERPHONE study as well as the results of other WHO activities under the International EMF Project. When these studies are published, Health Canada will review their content and determine if the Code needs to be revised. (18) Are there any internationally recognized procedures for RF exposure standard development?In 2006, the World Health Organization (WHO) published a document entitled Framework for Developing Health-based EMF Standards (http://www.who.int/peh-emf/standards/framework/en/). The Framework provides advice on how to develop science-based limits that will protect the health of the population from exposure to electromagnetic fields (EMF). Health Canada's guideline development procedures are in line with the guiding principles outlined in the WHO Framework. (19) Why did Canada develop its own RF exposure guidelines rather than adopt an existing international standard?Most industrialized countries consider it important to have guidelines for the protection of their citizens from exposure to RF fields. Two approaches are possible for achieving this protection: (1) develop their own national guidelines, or (2) adopt guidelines from other countries or organizations. Canada was one of the first countries to recognize the need for RF exposure guidelines and first developed them in 1979. Since then, these guidelines have been periodically updated. However, since international tendencies are moving towards universal standards, it is not unforeseeable that Canada may in the future adopt an internationally accepted standard. (20) Why do some countries have more stringent RF exposure standards? Are individuals in these countries receiving a greater level of protection?RF exposure standards have been developed by a number of organizations and countries over the past three decades. In North America and most of Europe, these standards have generally been based on the lowest exposure level at which potential harmful effects to humans could occur. Safety factors are then incorporated to arrive at recommended exposure levels for protection of the general public and personnel working in the RF environment. Not all standards throughout the world have the same recommended exposure limits; some are more stringent than others. The variations of recommended limits may be attributed to differences in the philosophy, the methodology and the interpretation of scientific data used for standard development. However, recognized exposure standards that are based on established effects should be distinguished from some municipal and/or state guidelines that are based on socio-political considerations. There is no scientific basis to support a conclusion that individuals living in countries with more stringent exposure standards receive a greater level of protection. (21) What is the precautionary principle and when should it be used?The precautionary principle (PP) is a public policy approach for risk management of possible, but unproven, adverse health effects. The extent of PP ranges from monitoring scientific developments and providing information to stronger measures such as lowering exposures. The increasing public concern over the RF health issue has led to demands for industry and regulatory authorities to apply PP to the use of cell phones and the proposed construction of new broadcasting and radiocommunication installations. The application of PP should be proportional to the level of risk and its associated uncertainty, the severity of the outcome, and the level of societal benefit. In the context of RF fields from broadcasting and radiocommunication installations and apparatus, health risks from exposure below the limits specified in Safety Code 6 have not been established. Therefore, if precautionary measures are introduced to reduce exposure levels, it is recommended that they be made voluntary. For example, if you are concerned about RF exposure, you may apply PP by limiting the length of your calls on cell phones and using a "hands-free" device that keeps the cell phone away from your head and body. Industry Canada's Role in Protecting the General Public from RF Exposure(22) Who regulates broadcasting and radiocommunication installations and apparatus in Canada?Radiocommunication, including technical aspects related to broadcasting, is under the responsibility of the Department of Industry (Industry Canada), which has the power to establish standards, rules, policies and procedures. Industry Canada, under this authority, has adopted Safety Code 6 for the protection of the general public from RF overexposure. All installations and apparatus must comply with Safety Code 6. (23) How does Industry Canada ensure that radiocommunication and broadcasting installations respect Health Canada's limits for the protection of the public from RF fields?While the responsibility for developing Safety Code 6 rests with Health Canada, Industry Canada has adopted the same guideline for the purpose of protecting the general public. Industry Canada requires that all proponents and operators ensure that their radiocommunication and broadcasting installations comply with Safety Code 6 at all times. Proponents and operators must also consider the combined effects of nearby installations within the local radio environment. For more information, consult CPC-2-0-03. Furthermore, Industry Canada conducts its own assessments and audits as required. See Questions 25 and 29 for further details. (24) Are RF field measurements required? Why or why not?RF field measurements take into consideration local terrain and structures and indicate actual levels, whereas calculation is a prediction that includes many assumptions erring on the side of caution. Industry Canada requires proponents and operators of radiocommunication and broadcasting installations to take RF field measurements to demonstrate compliance where it is suspected that the limits in Safety Code 6 for the protection of the general public might be exceeded. Every year there are tens of thousands of new and amended radiocommunication and broadcasting installations in Canada. The vast majority of these installations comply with Safety Code 6 by a very wide margin. Industry Canada has confirmed this by conducting many RF field measurements. Experience has also shown that calculations based on sound engineering practices ensure the protection of the general public. This is not only because Industry Canada has compared the results of calculations with those from actual measurements but also because certain safety factors are included in the calculations. For example, the analysis assumes that all transmitters are operating at the same time, which has a low probability of actually occurring for most radiocommunication installations. Several other assumptions erring on the side of caution/safety serve to further ensure the protection of the public. In rare cases where Industry Canada believes Safety Code 6 limits for the protection of the general public might be exceeded, the Department will immediately approach the proponent or operator. If the operator wishes to continue transmitting, or if the proponent wishes to continue with the proposal, Industry Canada will work with them to ensure that the installation complies with Safety Code 6. Asking for RF field measurements to demonstrate compliance is one of several methods Industry Canada may employ. For example in the case of a proposed new installation, Industry Canada may choose to issue conditional authority. Once the installation is built, the proponent will be required to take measurements to demonstrate compliance and to take immediate action to bring the installation into Safety Code 6 compliance should the measurement results show non-compliance. Industry Canada will only issue final authorization when it is satisfied that the installation complies with Safety Code 6 for the protection of the general public. (25) Are multiple antenna towers and broadcast antennas safe?Yes, provided that they comply with the guidelines contained in Safety Code 6. Industry Canada requires antenna proponents to evaluate the compliance to ensure that the cumulative fields produced by all antennas at a multiple antenna site are within the guidelines. (26) I am concerned whether a site in my area is in compliance with Safety Code 6. What should I do about it?Industry Canada requires all radiocommunication and broadcasting installations to comply with Safety Code 6 on an ongoing basis so that the general public is not subjected to exposure levels above the limits of Safety Code 6. Antenna proponents are required to perform an assessment of RF exposure on proposed antenna systems prior to installation to ensure compliance, and to keep records of the assessment. If you require information regarding compliance on a radiocommunication or broadcasting proposal or installation in your area, you should contact the proponent or operator of the installation. If the proponent/operator you have contacted does not provide the pertinent information within a reasonable time frame, contact your local Industry Canada office. Industry Canada may ask the proponent/operator to provide the information or, where the Department has concerns about compliance, it may carry out its own assessment. If the information provided and/or the Department's own assessment suggest that there is a potential for non-compliance, then Industry Canada will verify that the radiocommunication or broadcasting proponent/operator has taken the necessary mitigation measures (Please refer to Question 29) to ensure compliance with Safety Code 6. (27) How do I get an independent RF field measurement to ensure that the site I am concerned about meets the required limits? What should I look for?You can procure the services of competent technical personnel from reputable associations/companies to make independent measurements. The person making such an assessment must: be knowledgeable in the area of Safety Code 6 RF measurements; have the appropriate instruments to perform a proper RF field survey; and be able to interpret the measurement results. The results should be properly documented in a report, including a site map, the locations surveyed and the measurement results, details on the instrument(s) used, the method of measurement, abnormalities observed, as well as the measurement uncertainties. A properly documented report, in addition to the measurements conducted by competent personnel, provides a proper record of the survey and confidence in the results. If you want to conduct your own measurements, be aware that over the years tools have been marketed directly to consumers by vendors for this purpose. However, most of these tools work only on selected frequencies and are not calibrated (against a known standard), and therefore cannot provide reliable results. Before buying or using such a tool, make sure you understand its specifications and limitations, as well as how the tool works. (28) Who inspects or audits radiocommunication and broadcasting installations to ensure compliance?All proponents and operators of antenna systems are required by Industry Canada to comply with Safety Code 6 for the protection of the general public on an ongoing basis taking into consideration the local radio environment. Industry Canada also conducts audits to ensure compliance. Our experience from field measurements has demonstrated that, for the vast majority of radiocommunication and broadcasting installations, in areas accessible to the general public, the RF field levels are at a very small fraction of the Safety Code 6 limits. Therefore, Industry Canada concentrates the auditing effort in ensuring compliance of:
where these sites are in proximity to publicly accessible areas. Industry Canada requires proponents and operators of antenna systems to take immediate action at any site if it believes that Safety Code 6 is not being respected. Mitigation measures may include area demarcation (signs), accesses control (fences) and/or changes to the station(s) parameters. (29) What about amateur radio stations? Are they checked for compliance and are their emissions considered safe?All amateur radio operators must operate their amateur radio installations in compliance with Safety Code 6. In general, Industry Canada does not verify amateur radio installations for compliance, and relies on the operators to ensure compliance. Amateur radio operators are knowledgeable about radio equipment and many amateur radio associations provide extensive information and training to their members about RF safety and compliance with Safety Code 6. If you have concerns about an amateur radio installation in your neighbourhood, you should discuss them with the operator. In most cases, amateur radio operators are quite willing to discuss such issues with their neighbours. (30) Can the land-use authority (LUA) or municipality set its own RF exposure limits?Radiocommunication, including the technical aspects of broadcasting, is under the responsibility of the Department of Industry (Industry Canada), which has the power to establish standards, rules, policies and procedures regarding radiocommunication. Industry Canada, under this authority, has adopted Safety Code 6 for the protection of the general public from RF overexposure. All radiocommunication and broadcasting installations and apparatus must comply with Safety Code 6. Industry Canada requires antenna proponents to consult with LUAs before building or modifying antenna systems following the consultation process outlined in CPC-2-0-03. Although some LUAs have endeavoured to establish their own RF exposure limits, it is Industry Canada's view that they have no authority to establish and enforce exposure limits different from those adopted by Industry Canada. RF Exposure Limits for Transmitting Base Stations and Handheld/Portable Devices(31) Are the exposure limits for portable transmitters (e.g. cell phones) and antenna towers the same?The exposure limits for portable transmitters (e.g. cell phones) and antenna towers are different because of different exposure conditions. Portable transmitters are normally used in close proximity to the body and result in partial body exposures. On the other hand, antenna towers are located at far distances from the body, and thus RF fields from them give rise to whole-body exposure. (32) What is specific absorption rate (SAR)? Where can I obtain SAR data for my cell phone?Industry Canada requires that all portable and handheld radiocommunication devices, including cell phones, sold in Canada comply with Safety Code 6 SAR limits. The specific absorption rate (SAR) is the rate at which RF energy is absorbed by a defined amount of mass of a biological body. SAR is expressed in units of watts per kilogram (W/kg). The SAR value of your cell phone is normally published in the user manual or you can contact the manufacturer to obtain this information. Additionally, there are many independent websites which publish SAR values for many models of cell phones. For Further Information(33) Where can I find more information on RF exposure standards and health?More information in the area of RF exposure and health is available at the following web sites: Health Canada
The Royal Society of Canada - Expert Panel on Potential Health Risks of Radiofrequency Fields from Wireless Telecommunication Devices
The U.S. Food and Drug Administration
The U.S. Federal Communications Commission - Questions and Answers about Biological Effects and Potential Hazards of Radiofrequency Electromagnetic Fields
(34) Where can I get more information about Industry Canada's requirement to comply with Safety Code 6?The following Industry Canada procedures contain information on compliance with Safety Code 6:
The following Industry Canada guidelines contain information on RF field Measurements and Compliance Measures:
If you would like to contact Industry Canada's local district offices, consult the following:
(35) I have a question on Safety Code 6. Who should I contact?
For more information on Safety Code 6, contact: |
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| Created: 2007-07-26 Updated: 2007-10-02 |
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