"The data in this report cannot therefore be used to infer safety, or lack of safety, of children in any of the tested locations."
Attention: Dr. Andrew Zuckerman, Chief Operating Officer MCPS Board of Education Members
This letter of comment has been prepared after reviewing the Montgomery County Public Schools Radiofrequency (RF) Summary Monitoring Report dated July 2015 produced by AECOM Environment.
1) The instrument cited as being used for the peak measurements in section 7, a Narda SRM-3006, is not suitable to measure the very short (1 millisecond) spikes typically found in WiFi 802.11n communication. As stated on page 7-1, each data sweep takes 550 milliseconds, making the instrument unsuitable for reliably logging the short bursts typical in 802.11n WiFi communications. Palit et al conclude that 50% of the uplink traffic will be in bursts shorter than 2 milliseconds. The peak levels of those packets will not be reliably logged by a device with a 550 millisecond sweep time.
Palit et al, 2012. Anatomy of WiFi Access Traffic of Smartphones and Implications for Energy Saving Techniques. International Journal of Energy, Information and Communications, Vol. 3, Issue 1.
2) Even the average-level tests seem inconsistent with engineering reality. Figure 7.1 shows a background noise level mostly flat between 2.4GHz and 5.8Ghz. That noise (typically -70dBm) is generally consistent with the internal thermal noise in a quality wide-band measuring instrument. Two tiny peaks out of that noise are represented to be the "average electric field generated at one foot away from an AP in use at Beverly Farms Elementary School." Even with just the 802.11n beacon-frame idling, the peak field a foot away from an access point should be a million times higher than the levels of figure 7.1. Why do we just see a blip on the chart? Clearly some unusual 'averaging' has occurred, yet the parameters of that averaging, and the potential clinical implications of that averaging, are not noted in the annotation to the Figures. Further, Figure 7.2 shows a background noise level some 10dB higher than figure 7.1, something that would be very unusual in measurements at these Gigahertz frequencies.
3) The RF exposure estimates are additionally inadequate because, in reality, there is no way to meet the distancing that AECOM’s report bases it’s measurements on for an individual student. In normal use, kids hover over devices. They hug them to the body. They put them in their laps at lunchtime, on the couch and in bed doing homework. It is entirely unrealistic to expect teachers and parents to guarantee that students always keep their Chromebooks at some arbitrary distance during use.
Attention: Dr. Andrew Zuckerman, Chief Operating Officer MCPS Board of Education Members
December 1, 2015
This letter of comment has been prepared after reviewing the Montgomery County Public Schools Radiofrequency (RF) Summary Monitoring Report dated July 2015 produced by AECOM Environment.
1) The instrument cited as being used for the peak measurements in section 7, a Narda SRM-3006, is not suitable to measure the very short (1 millisecond) spikes typically found in WiFi 802.11n communication. As stated on page 7-1, each data sweep takes 550 milliseconds, making the instrument unsuitable for reliably logging the short bursts typical in 802.11n WiFi communications. Palit et al conclude that 50% of the uplink traffic will be in bursts shorter than 2 milliseconds. The peak levels of those packets will not be reliably logged by a device with a 550 millisecond sweep time.
Palit et al, 2012. Anatomy of WiFi Access Traffic of Smartphones and Implications for Energy Saving Techniques. International Journal of Energy, Information and Communications, Vol. 3, Issue 1.
2) Even the average-level tests seem inconsistent with engineering reality. Figure 7.1 shows a background noise level mostly flat between 2.4GHz and 5.8Ghz. That noise (typically -70dBm) is generally consistent with the internal thermal noise in a quality wide-band measuring instrument. Two tiny peaks out of that noise are represented to be the "average electric field generated at one foot away from an AP in use at Beverly Farms Elementary School." Even with just the 802.11n beacon-frame idling, the peak field a foot away from an access point should be a million times higher than the levels of figure 7.1. Why do we just see a blip on the chart? Clearly some unusual 'averaging' has occurred, yet the parameters of that averaging, and the potential clinical implications of that averaging, are not noted in the annotation to the Figures. Further, Figure 7.2 shows a background noise level some 10dB higher than figure 7.1, something that would be very unusual in measurements at these Gigahertz frequencies.
3) The RF exposure estimates are additionally inadequate because, in reality, there is no way to meet the distancing that AECOM’s report bases it’s measurements on for an individual student. In normal use, kids hover over devices. They hug them to the body. They put them in their laps at lunchtime, on the couch and in bed doing homework. It is entirely unrealistic to expect teachers and parents to guarantee that students always keep their Chromebooks at some arbitrary distance during use.
4) The report concludes with classroom RF measurement comparisons to an outdated
2007 BioInitiative Report recommendation of 0.1 uW/cm2. (Section 7). Graphics need
to be re-drawn with comparisons to the 2012 recommended BioInitiative level, and do so
not only for a 12” spacing, but also for the one-inch distance measured from the
Chromebook (Figure 7-3 and 7-4). Using an arbitrary 12” distance to report and compare
to either the 2007 or 2012 BioInitiative recommendations will seriously underestimate
RF exposures since students don’t always (or even typically) maintain a foot of distance.
Their ‘leaning in’ and having to place their faces close to the device is common usage,
and is unavoidable.
5) The methodology is not specific as to the number of operating devices and clustering of students at work – which is necessary to characterize exposures from a room full of operational wireless devices. Figure 2.1 shows multiple wireless devices connected to one wireless router. Measuring one or several Chromebooks rather than one Chromebook for each of the 25-35 students plus router isn't how a normal classroom operates. It does not produce RF measurements of a typical class using many wireless devices at once, so this is a fundamental flaw. It will underestimate RF exposures.
6) There is also a comment to be made here about the setup – how does this methodology reasonably reflect how smaller or younger children with short arms and torsos actually use tablets? What RF exposures they can expect to receive? The likely consequence to the measurements is greater exposure. Unless the students are using chopsticks instead of their fingers, or are using wired keyboards that increase the distance to the wireless device, RF exposures will be worse for the younger or smaller-stature students.
7) This Report appears to legitimize MCSD’s use of wireless in the classroom by asserting compliance with the 2007 BioInitiative Report recommendation, yet the report does not mention the significant revision of that threshold in the years between 2007 and 2012. Both BioInitiative Reports clearly state that their recommendations are interim and ‘that they may have to go lower.’ Recent studies of students reporting headache, irritability, concentration and behavior problems at levels as low as 0.003-0.006 uW/cm2, indicate that neither BioInitiative Report threshold may be low enough to assure safety.
As the co-editor of the BioInitiative Reports, and a founding member of the BioInitiative Working Group, the way in which our work has been invoked is not consistent with the findings of the BioInitiative Reports overall. The conclusions of this report cannot be said to give a positive assertion of safety because of the degree of uncertainty over whether the testing equipment was adequate (we believe it was not); the lack of comparison data; and the failure to measure RF exposures at realistic distances from the student(s).
8) Correct BioInitiative citations are:
BioInitiative Working Group, Cindy Sage and David O. Carpenter, Editors. BioInitiative Report: A Rationale for Biologically-based Public Exposure Standards for Electromagnetic Radiation at
5) The methodology is not specific as to the number of operating devices and clustering of students at work – which is necessary to characterize exposures from a room full of operational wireless devices. Figure 2.1 shows multiple wireless devices connected to one wireless router. Measuring one or several Chromebooks rather than one Chromebook for each of the 25-35 students plus router isn't how a normal classroom operates. It does not produce RF measurements of a typical class using many wireless devices at once, so this is a fundamental flaw. It will underestimate RF exposures.
6) There is also a comment to be made here about the setup – how does this methodology reasonably reflect how smaller or younger children with short arms and torsos actually use tablets? What RF exposures they can expect to receive? The likely consequence to the measurements is greater exposure. Unless the students are using chopsticks instead of their fingers, or are using wired keyboards that increase the distance to the wireless device, RF exposures will be worse for the younger or smaller-stature students.
7) This Report appears to legitimize MCSD’s use of wireless in the classroom by asserting compliance with the 2007 BioInitiative Report recommendation, yet the report does not mention the significant revision of that threshold in the years between 2007 and 2012. Both BioInitiative Reports clearly state that their recommendations are interim and ‘that they may have to go lower.’ Recent studies of students reporting headache, irritability, concentration and behavior problems at levels as low as 0.003-0.006 uW/cm2, indicate that neither BioInitiative Report threshold may be low enough to assure safety.
As the co-editor of the BioInitiative Reports, and a founding member of the BioInitiative Working Group, the way in which our work has been invoked is not consistent with the findings of the BioInitiative Reports overall. The conclusions of this report cannot be said to give a positive assertion of safety because of the degree of uncertainty over whether the testing equipment was adequate (we believe it was not); the lack of comparison data; and the failure to measure RF exposures at realistic distances from the student(s).
8) Correct BioInitiative citations are:
BioInitiative Working Group, Cindy Sage and David O. Carpenter, Editors. BioInitiative Report: A Rationale for Biologically-based Public Exposure Standards for Electromagnetic Radiation at
www.bioinitiative.org, December 31, 2012.
BioInitiative Working Group, Cindy Sage and David O. Carpenter, Editors. BioInitiative Report: A Rationale for a Biologically-based Public Exposure Standard for Electromagnetic Fields (ELF and RF) at www.bioinitiative.org, August 31, 2007
CONCLUSION
The data in this report cannot therefore be used to infer safety, or lack of safety, of children in any of the tested locations.
Respectfully submitted,
Cindy Sage. MA
Sage Associates
Co-Editor, BioInitiative 2007 and 2012 Reports
Prof. Trevor Marshall, PhD
Director, Autoimmunity Research Foundation,
Senior Member IEEE,
Founding chair (retired) IEEE EMBS (Buenaventura Chapter)
Fellow, European Association for Predictive, Preventive and Personalised Medicine (Brussels)
International Expert Council, Community of Practice: Preventative Medicine (Moscow)
BioInitiative Working Group, Cindy Sage and David O. Carpenter, Editors. BioInitiative Report: A Rationale for a Biologically-based Public Exposure Standard for Electromagnetic Fields (ELF and RF) at www.bioinitiative.org, August 31, 2007
CONCLUSION
The data in this report cannot therefore be used to infer safety, or lack of safety, of children in any of the tested locations.
Respectfully submitted,
Cindy Sage. MA
Sage Associates
Co-Editor, BioInitiative 2007 and 2012 Reports
Prof. Trevor Marshall, PhD
Director, Autoimmunity Research Foundation,
Senior Member IEEE,
Founding chair (retired) IEEE EMBS (Buenaventura Chapter)
Fellow, European Association for Predictive, Preventive and Personalised Medicine (Brussels)
International Expert Council, Community of Practice: Preventative Medicine (Moscow)
Read The Full Letter HERE.
Watch Cindy Sage Speak in her Interview For the Movie Generation Zapped
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