Tarmo Koppel

Radiofrequency radiation at Stockholm Central Railway Station in Sweden and some medical aspects on public exposure to RF fields

The Stockholm Central Railway Station in Sweden was investigated for public radiofrequency (RF) radiation exposure. The exposimeter EME Spy 200 was used to collect the RF exposure data across the railway station. The exposimeter covers 20 different radiofrequency bands from 88 to 5,850 MHz. In total 1,669 data points were recorded. The median value for total exposure was 921 μW/m2 (or 0.092 μW/cm2; 1 μW/m2=0.0001 μW/cm2) with some outliers over 95,544 μW/m2 (6 V/m, upper detection limit). The mean total RF radiation level varied between 2,817 to 4,891 μW/m2 for each walking round. High mean measurements were obtained for GSM + UMTS 900 downlink varying between 1,165 and 2,075 μW/m2. High levels were also obtained for UMTS 2100 downlink; 442 to 1,632 μW/m2. Also LTE 800 downlink, GSM 1800 downlink, and LTE 2600 downlink were in the higher range of measurements. Hot spots were identified, for example close to a wall mounted base station yielding over 95,544 μW/m2 and thus exceeding the exposimeters detection limit. Almost all of the total measured levels were above the precautionary target level of 3–6 μW/m2 as proposed by the BioInitiative Working Group in 2012. That target level was one-tenth of the scientific benchmark providing a safety margin either for children, or chronic exposure conditions. We compare the levels of RF radiation exposures identified in the present study to published scientific results reporting adverse biological effects and health harm at levels equivalent to, or below those measured in this Stockholm Central Railway Station project. It should be noted that these RF radiation levels give transient exposure, since people are generally passing through the areas tested, except for subsets of people who are there for hours each day of work.

Case-control study on occupational exposure to extremely low-frequency electromagnetic fields and glioma risk

BACKGROUND Exposure to extremely low-frequency electromagnetic fields (ELF-EMF) was in 2002 classified as a possible human carcinogen, Group 2B, by the International Agency for Research on Cancer at WHO. METHODS Life time occupations were assessed in case-control studies during 1997-2003 and 2007-2009. An ELF-EMF Job-Exposure Matrix was used for associating occupations with ELF exposure (μT). Cumulative exposure (μT-years), average exposure (μT), and maximum exposed job (μT) were calculated. RESULTS Cumulative exposure gave for astrocytoma grade IV (glioblastoma multiforme) in the time window 1-14 years odds ratio (OR) = 1.9, 95% confidence interval (CI) = 1.4-2.6, p linear trend <0.001, and in the time window 15+ years OR = 0.9, 95%CI = 0.6-1.3, p linear trend = 0.44 in the highest exposure categories 2.75+ and 6.59+ μT years, respectively. CONCLUSION An increased risk in late stage (promotion/progression) of astrocytoma grade IV for occupational ELF-EMF exposure was found.

High radiofrequency radiation at Stockholm Old Town: An exposimeter study including the Royal Castle, Supreme Court, three major squares and the Swedish Parliament

Exposure to radiofrequency (RF) radiation was classified as a possible human carcinogen, Group 2B, by the International Agency for Research on Cancer at WHO in 2011. The exposure pattern is changing due to the rapid development of technology. Outdoor RF radiation level was measured during five tours in Stockholm Old Town in April, 2016 using the EME Spy 200 exposimeter with 20 predefined frequencies. The results were based on 10,437 samples in total. The mean level of the total RF radiation was 4,293 µW/m2 (0.4293 µW/cm2). The highest mean levels were obtained for global system for mobile communications (GSM) + universal mobile telecommunications system (UMTS) 900 downlink and long-term evolution (LTE) 2600 downlink (1,558 and 1,265 µW/m2, respectively). The town squares displayed highest total mean levels, with the example of Järntorget square with 24,277 µW/m2 (min 257, max 173,302 µW/m2). These results were in large contrast to areas with lowest total exposure, such as the Supreme Court, with a mean level of 404 µW/m2 (min 20.4, max 4,088 µW/m2). In addition, measurements in the streets surrounding the Royal Castle were lower than the total for the Old Town, with a mean of 756 µW/m2 (min 0.3, max 50,967 µW/m2). The BioInitiative 2012 Report defined the scientific benchmark for possible health risks as 30–60 µW/m2. Our results of outdoor RF radiation exposure at Stockholm Old Town are significantly above that level. The mean exposure level at Järntorget square was 405-fold higher than 60 µW/m2. Our results were below the reference level on 10,000,000 µW/m2 established by the International Commission on Non-Ionizing Radiation Protection (ICNIRP), which, however, are less credible, as they do not take non-thermal effects into consideration and are not based on sound scientific evaluation. Our highest measured mean level at Järntorget was 0.24% of the ICNIRP level. A number of studies have found adverse, non-thermal (no measurable temperature increase) health effects far below the ICNIRP guidelines.

Case-Control Study on Occupational Exposure to Extremely Low-Frequency Electromagnetic Fields and the Association with Meningioma

Objective Exposure to extremely low-frequency electromagnetic fields (ELF-EMF) was in 2002 classified as a possible human carcinogen, Group 2B, by the International Agency for Research on Cancer at WHO based on an increased risk for childhood leukemia. In case-control studies on brain tumors during 1997–2003 and 2007–2009 we assessed lifetime occupations in addition to exposure to different agents. The INTEROCC ELF-EMF Job-Exposure Matrix was used for associating occupations with ELF-EMF exposure (μT) with meningioma. Cumulative exposure (μT-years), average exposure (μT), and maximum exposed job (μT) were calculated. Results No increased risk for meningioma was found in any category. For cumulative exposure in the highest exposure category 8.52+ μT years odds ratio (OR) = 0.9, 95% confidence interval (CI) = 0.7–1.2, and p linear trend = 0.45 were calculated. No statistically significant risks were found in different time windows. Conclusion In conclusion occupational ELF-EMF was not associated with an increased risk for meningioma.

Screen Elements Made of Perforated Steel Tape and their Application for Shielding Electromagnetic Fields

In the present work the methods for producing flat and three-dimensional shielding screens from the perforated steel tape are proposed. The possible application variants of mentioned screens are offered and analyzed. Main attention is given for producing one-layer and multi-layer screens with cellular structure due to its relatively low weight and technological elasticity – complex three-dimensional structures could be done successfully.Examples of produced shielding screens from the perforated steel tape for protection from electromagnetic fields in different frequency range are offered and tested. The efficiency of a shielding material was determined by measuring the magnetic field before and after applying the shielding material. Distribution of the magnetic field behind the shielding screen was determined by software vector mapping. Shielding efficiency was measured for 1) a three-layer perforated steel screen; 2) an one-layer perforated steel screen - shielding screen was placed in between the magnetic field source and the measurement point forming a two dimensional screen; 3) copper composite sprayed screen. During experimental investigation it was established, that a three-layer perforated steel screen application allowed the 27% reduction in the magnetic field, while one-layer perforated steel screen gave only 12% reduction. Copper composite sprayed screen reduced magnetic field by 15%.Recommendations for producing the multi-layer perforated steel screen accordingly to shielding efficiency are elaborated and laid down. The discussed material carries also ecological significance, since the material is produced by waste products (after stumping etc.). Therefore the production of such materials comes with reduced cost both in light of capital expenditures and ecological footprint.

Shielding static magnetic fields from Magnetic Resonance Imaging units by ferromagnetic material

This study investigated the effectiveness of iron sheets in shielding static magnetic fields from MRI units. The neighbouring rooms of two 3T MRI units were measured, located in different healthcare facilities, one fully shielded and the other only partially shielded (only the ceiling was shielded) from static magnetic fields. In order to achieve a significant shielding effectiveness from the MRI static magnetic field, the examination room should be fully shielded, including the walls, ceiling and the floor. The MRI unit with only partially shielded room allowed ten times more static magnetic field to propagate into the premises one floor below. The average static magnetic field below partially shielded MRI unit was 1.178 mT, whereas below fully shielded MRI unit 0.176 mT.

Measurements of Radiofrequency Radiation with a Body-Borne Exposimeter in Swedish Schools with Wi-Fi

Introduction Wireless access to the Internet is now commonly used in schools. Many schools give each student their own laptop and utilize the laptops and wireless fidelity (Wi-Fi) connection for educational purposes. Most children also bring their own mobile phones to school. Since children are obliged by law to attend school, a safe environment is important. Lately, it has been discussed if radiofrequency (RF) radiation can have long-term adverse effects on children’s health. Method This study conducted exposimetric measurements in schools to assess RF emissions in the classroom by measuring the teachers’ RF exposure in order to approximate the children’s exposure. Teachers in grades 7–12 carried a body-borne exposimeter, EME-Spy 200, in school during 1–4 days of work. The exposimeter can measure 20 different frequency bands from 87 to 5,850 MHz. Results Eighteen teachers from seven schools participated. The mean exposure to RF radiation ranged from 1.1 to 66.1 µW/m2. The highest mean level, 396.6 µW/m2, occurred during 5 min of a lesson when the teacher let the students stream and watch YouTube videos. Maximum peaks went up to 82,857 µW/m2 from mobile phone uplink. Discussion Our measurements are in line with recent exposure studies in schools in other countries. The exposure levels varied between the different Wi-Fi systems, and if the students were allowed to use their own smartphones on the school’s Wi-Fi network or if they were connected to GSM/3G/4G base stations outside the school. An access point over the teacher’s head gave higher exposure compared with a school with a wired Internet connection for the teacher in the classroom. All values were far below International Commission on Non-Ionizing Radiation Protection’s reference values, but most mean levels measured were above the precautionary target level of 3–6 µW/m2 as proposed by the Bioinitiative Report. The length of time wireless devices are used is an essential determinant in overall exposure. Measures to minimize children’s exposure to RF radiation in school would include preferring wired connections, allowing laptops, tablets and mobile phones only in flight mode and deactivating Wi-Fi access points, when not used for learning purposes.

Voltage transients measurements and power line communication

Power line communication (PLC) connects energy producers with energy consumers. In the European Union stricter guidelines are under development to limit disturbances in the 2-150 kHz frequency range, because devices utilising PLC do not work. This study measured voltage transients in 22 locations and identified sources for noise. Home environments and public buildings were measured. Measurements were conducted in the frequency range of 150 kHz-500 kHz (according to EN 55011 to EN 55022) and in the lower frequency range of 3 kHz to 95 kHz. Results indicate that voltage transients are generated mostly by switching mode power supplies, pumps, rectifiers, inverters and even low quality smart meters. Several of these devices exceeded PLC standard level, 122 dBμV. Additionally we demonstrate that basic power quality recordings do not provide enough information to mitigate PLC problems occurring within microseconds and frequency specific voltage transient measurements are needed.