Section D — The Six Policy Questions
Question 3. What means are available to readily identify whether proposed installations may create radiofrequency fields in excess of established exposure limits in areas where people live and work?
Over the past 25 years, a number of means have been devised to predict when a proposed antenna installation may create radiofrequency fields in excess of the established exposure limits for humans. Essentially, for all of these tools, the user provides the technical operating parameters of the proposed radio apparatus and antenna installation, and the tool supplies the estimated distances necessary (from the radiating antenna to the exposed human) to remain compliant with the established (RF) exposure limits. These predictive tools have evolved from rather simplistic (look-up) tables, to a series of mathematical field-strength equations, to sophisticated computer software that will produce 3D graphic images that outline the estimated compliance distances. As the tools have become more sophisticated, more (and more varied) technical parameters related to the radio equipment and its surroundings can be entered for processing. Today, calibrated field-strength measurements, taken from actual radio installations, are used to refine and confirm the accuracy of the computer programs available.
Clearly, the answer to Policy Question 3 is that there are many means available to readily identify whether proposed installations may create radiofrequency fields in excess of established exposure limits in areas where people live and work. To provide a more refined answer to this question one would have to know to whom the means would be readily available and for what purpose. Predictive tools and processes used by Industry Canada within its antenna authorization processes would be too complex and expensive for some of Canada's antenna proponents seeking to confirm that their proposed installation or modification will be compliant with the established exposure limits. Finally, one should ask whether there are means readily available to land-use authorities and to concerned members of the public to confirm that an antenna proposed for their vicinity will be compliant to the established exposure limits. This section of the National Antenna Tower Policy Review will examine Canada's established exposure limits within Safety Code 6, discuss the use of current RF exposure predictive tools by Industry Canada and some radio users, and offer some views on the use of those (or other) tools, by local governments and concerned citizens.
A. An Overview of Safety Code 6
Safety Code 6Footnote 189 (SC 6 or the Code) is Canada's national standard on human exposure to radiofrequency electromagnetic fields. The Code is a comprehensive document that sets out safety requirements for the installation and use of radiofrequency (RF) and microwave devices that operate in the frequency range from 3 kHz to 300 GHz .Footnote 190 It was first published in 1979 by the Radiation Protection Bureau of the Department of National Health and Welfare. In 1991 and 1999 SC 6 was revised to reflect advances in technology, the proliferation of wireless communications and new biological studies on the hazards of exposure to radiofrequency energy. The 1991 revisions extended the range of frequencies covered by the Code to 300 GHz, reduced the recommended exposures for members of the public for particular frequency bands, and adjusted most exposures to make them more frequency dependent (to account for differing body size and resonance).
The Code provides two sets of RF exposure limits that are based upon the status of the individual who may be exposed: radiofrequency and microwave exposed workers who may be exposed in the course of their daily work and other persons including the general public who may be exposed at any time or place.Footnote 191 The exposure limits are specified by Electric Field - as measured in volts per metre (V/m), Magnetic Field - as measured in amperes per metre (A/m) and Power Density - as measured in watts per metre squared (W/m2 ) or milliwatts per centimetre squared (mW/cm2).Footnote 192 In terms of power density, the maximum permissible exposures for both groups (occupational and public) may be averaged over specified periods of time (measured in minutes) and the average is not to exceed the limit for continuous exposure. Of course, this policy review is concerned about the application of SC 6 limits as specified for the general public.
B. Industry Canada and the Implementation of SC 6
The Consumer and Clinical Radiation Protection Branch of Health Canada produces Safety Code 6 as a guidance document. The Code has no independent legal status, but compliance can be made mandatory by its incorporation into validly enacted laws, regulations or standards. Industry Canada has required compliance with SC 6 by incorporating it into radio regulatory provisions dealing with handheld radio apparatus (like cell phones) and antenna installations. CPC-2-0-03 warns all Type 1 and Type 2 antenna proponents that "Industry Canada requires that radio stations be installed and operated in a manner that complies with Safety Code 6."Footnote 193 For Type 1 antenna installations the CPC provides:
The authorization process for Type 1 stations includes an initial analysis that considers the potential effect of the proposed station within the existing radio environment. Where the analysis indicates that the maximum RF field level permitted by Safety Code 6 may be exceeded, the applicant may be required to undertake mitigation measures. These measures may include reducing the transmitter power or duration of transmission, changing the type, direction or height of the antenna, or restricting access to areas near to the antenna. Where the calculation indicates that the proposed station will meet Safety Code 6, Industry Canada will continue the normal authorization process.Footnote 194
Type 2 antenna installations are not subject to any form of prior authorization by Industry Canada. The onus is placed upon the owner/operator to ensure that the radio equipment is compliant with SC 6 requirements and the department may conduct audits of operational radio stations. For Type 2 antenna installations, such as those of amateur radio operators, CPC-2-0-03 states:
Type 2 stations must comply with Safety Code 6. Where it is expected that the operation of the proposed station will result in non-compliance with Safety Code 6, mitigation measures as described for Type 1 must be pursued by the owner of the station.Footnote 195
As noted above, the authorization processes for Type 1 radio installations, which would include broadcasters and site-specific wireless carriers, provide for an 'initial analysis' to ensure that the proposed station or modification is compliant with Safety Code 6.
The Department of Industry has a three step screening and evaluation process for ensuring that Type 1 antenna installations will operate within SC 6 exposure limits. If a flag is raised at one level, the evaluation is intensified at the next. The three stages are as follows:Footnote 196
Step 1: The first stage involves looking at a listing of service categories to see if the antenna system under consideration is listed. The radio service categories listed are known to produce very low radiofrequency fields within the area surrounding the antenna where people may be present.Footnote 197 Listed services are exempt from further RF exposure evaluation as long as the antenna height (as measured in metres above the ground or rooftop) and power (as measured in EIRP or equivalent isotopically radiated power) are within the limits specified on the exclusion list. For example, if the lowest point of the proposed antenna is 10 metres in height or greater and the total EIRP is 1649 watts or less, the proposal is screened out of further evaluation. This exclusion list was first published and used in 1998 by the US Federal Communication Commission (FCC). If a proposed antenna installation is not exempted under this stage it proceeds to Step 2.
Step 2: This step uses a template contained within Technical Note TN-261Footnote 198 to obtain a conservative estimate of the area, as measured out from the radiating antenna,Footnote 199 that would exceed the exposure limits specified for the general public within Safety Code 6. If the public might reasonably have physical access to the area that exceeds SC 6 levels, the proposal must be evaluated under Step 3. The template contained within TN-261 provides predicted radiofrequency fields that are based on a technical document that was created and used by the FCC. When possible, Industry Canada has attempted to harmonize its processing and evaluation policies for exposure to RF fields with those in the U.S.A.
Step 3: The third step involves using more sophisticated RF field assessment tools, such as the calculating module contained with the department's Automated Licensing System (ALS), or performing actual on-site measurements as soon as the antenna is operational.
In addition to the lists and templates discussed above, Industry Canada has three tools for predicting and measuring radiofrequency fieldsFootnote 200:
- Automated Licensing System (ALS). The ALS database contains information pertaining to existing antenna installations. In particular, the ALS contains a Safety Code 6 calculating module that determines whether a new installation will meet current RF exposure limits.
- Hi-Field Prediction Tool for Broadcast Tower Installations. This tool is used to predict whether a new installation will meet current RF exposure guidelines. The tool provides a simple graphical interface and outlines the RF field. Section 8.2 of BPR-1 discusses the Hi-field module and provides detailed information with respect to RF evaluations.
- Guidelines for the Measurement of Radiofrequency Fields at Frequencies from 3 kHz to 300 GHz (August 2000).Footnote 201 This document outlines some principles and background information for the measurement of radiofrequency electromagnetic fields. It also provides a number of recommended measurement procedures for the different types of telecommunication services. The techniques for both the near field and far field measurements are based on instrumentation currently available. The recommended procedures are not considered appropriate for the measurement of electromagnetic fields in the reactive near field region.
Industry Canada is in the process of improving upon the accuracy of the values obtained from the template set out within Technical Note TN-261 (for Step 2). Currently, the template does not apply to all service categories and it is based upon the simplest of scenarios - a single antenna, operating in a single frequency band and doing so in isolation from other antennas. The new technical document will consider scenarios involving multiple antenna sites operating at multiple frequencies.
C. Means Available to Radio Users to Ensure Compliance with SC 6
There are numerous means available to radio users in Canada to readily identify whether the antenna installations or modifications they are proposing may create radiofrequency fields in excess of those permitted under Safety Code 6. These tools range from computer programs that are commercially available for use by certified radio engineers to simple look-up tables suitable for amateur radio operators seeking to predict the fields from a typical amateur antenna installation.Footnote 202 Industry Canada publishes a look-up table for predicting the various RF exposure contours for compliance with Safety Code 6 limits for AM broadcasting undertakings and for 'low power' FM and TV stations.Footnote 203
Many of the formal written submissions filed by broadcasters and wireless carriers for this national policy review addressed SC 6 and the means available to them to assess their antenna proposals for compliance with it. The Canadian Association of Broadcasters (CAB) informed that the methods used to predict RF fields were well known to broadcasters because they were developed by joint government/industry committees with representation from equipment manufacturers and radiofrequency engineering consultants.Footnote 204 The CBC explained that:
... applications for new or modified broadcasting certificates must include a technical analysis [done by or on behalf of the broadcaster] demonstrating that operation of the proposed facilities will not produce electromagnetic fields higher than the Safety Code 6 limits at any location where public access is possible.Footnote 205
Within its submission, the Radio Advisory Board of Canada (RABC) confirmed that there are various means available to its members to predict RF fields to ensure compliance with SC 6.Footnote 206 The Canadian Wireless Telecommunications Association (CWTA) informed that all of the major wireless carriers have their own computer software for SC 6 compliance.Footnote 207
Representatives from the amateur radio community offered the opinion that the fields generated by amateur antenna installations are unlikely to encounter compliance problems in relation to Safety Code 6.Footnote 208 They confirmed that numerous means are available to amateurs for reliable RF field prediction through the use of mathematical tables and models that are similar to those available to commercial radio users.Footnote 209 If theoretical signal-level calculations are close to permitted levels, actual measurements are usually taken by the amateur to ensure compliance once the facility is operational.Footnote 210 Any disputes about RF predictions are resolved by Industry Canada.Footnote 211
D. Means Available to Land-Use Authorities and Citizens
Generally speaking, in circumstances when concerned citizens in Canada have objected to proposed antenna installations on the grounds that the radiofrequency fields generated may be hazardous to the health of the people living in the vicinity, they have tended to challenge the adequacy of Safety Code 6 itself as opposed to the evaluations done to ensure compliance with it.Footnote 212 Nevertheless, there are citizens and land-use authority staff who would like to be able to confirm the reliability of the SC 6 compliance data being provided by the antenna proponent to Industry Canada.
The very first challenge to those who may wish to confirm that a proposed antenna installation will generate RF fields that are in compliance with Safety Code 6, would be getting access to the compliance data which the proponent supplied to Industry Canada. CPC-2-0-03 does not require that Type 1 or Type 2 antenna proponents make this data available to land-use authorities or to the public. It is interesting to note that within a few of the formal submissions to this policy review provided by radio users, the view was expressed that such data should not be made generally available because citizens and land-use authorities would not have the knowledge or the resources to perform or confirm SC 6 evaluations.Footnote 213 Station data, including PCS/Cellular stations, has been made available to the general public through Industry Canada's Assignment and Licensing System (ALS) database and Spectrum Direct Web site.Footnote 214
If citizens or land-use authorities wanted to perform their own SC 6 evaluation of an antenna proposal they would require access to the technical parameters of the radio installation or modification under consideration and, likely, technical information about other existing or planned radio facilities in the area or at the same site. While some of the existing antenna siting protocols negotiated between Canada's wireless carriers and certain land-use authorities require the proponent to provide the basic technical parameters of the antenna under consideration, no protocol appears to provide access to the parameters of other radio installations in the immediate vicinity. Without such data, an SC 6 analysis would be incomplete.
Should a proposed antenna installation involve only a single antenna operating in one frequency band it may be possible for a concerned citizen or land-use authority representative to perform a rudimentary SC 6 evaluation if the basic technical parameters were made available. Likely, the best approach for the public would be to read over Safety Code 6 and to try to understand how to estimate the limits. In Appendix III of Safety Code 6 there is a sample calculation that can used as a model. Depending upon the radio facility under consideration, this type of calculation can become complex, but it will give a useful estimate of the radiofrequency fields within the areas where people may have access. While Safety Code 6 does try to provide guidance for the public to estimate limits, it can still be confusing. Industry Canada's document, Guidelines for the Measurement of Radiofrequency Fields at Frequencies from 3 kHz to 300 GHz (August 2000) is good supplementary reading for Safety Code 6.
As an alternative to using the methodologies provided within the Appendix III to SC 6, it should be noted that a member of the Amateur Radio Relay League (ARRL), who is located in Texas, maintains an Internet siteFootnote 215 that will calculate the power densities of proposed antenna facilities. While compliance is based on the FCC's regulations, they are similar to Canada's and can be used to obtain good estimates.
Once an antenna installation is established and operating, land-use authorities, community groups or citizens who are concerned about compliance to Safety Code 6 can perform actual field measurements from public areas around the facility. Inexpensive devices can be used, along with the formulas discussed above, to provide approximate compliance data. Companies such as Narda Safety Solutions,Footnote 216 Orgone Biophysical Research Laboratory Inc.Footnote 217 ETS LindgrenthatFootnote 218 sell RF field testing equipment. Use of such devices must be in accordance with Safety Code 6.Footnote 219
During consultations held with departmental staff at Health Canada,Footnote 220 it was learned that members of the Consumer and Clinical Radiation Protection Branch had created an RF field mapping system for cellular base stations.Footnote 221 The equipment can be mounted on the roof of an automobile and operated with minimal technical expertise. The automobile is driven in various patterns in proximity to the subject antenna site and RF field readings are recorded by location on the ground. The various locations of the device are determined using a geo-positioning unit (GPS) that is built in. Once the readings have been taken, a graphic print out of the contours of the RF fields in the vicinity is provided and can be used to determine compliance with Safety Code 6. At the time of the consultation, officials at Health Canada had not decided as to the terms and conditions applicable to making this monitoring device available outside of the department.