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1.
对北京中央电视塔周围25 km2区域电磁环境质量分别进行了射频的网格法手工监测和车载巡测自动监测,通过SPSS软件等对两种监测方法获取的数据进行了统计对比分析,发现两组数据在总体水平及数值分布特征上较为接近,因此车载巡测监测可以替代网格法监测。以车载巡测数据为基础,绘制了实测数据的道路电磁地图,利用插值法绘制了区域电磁地图,对区域电磁环境质量进行了直观表征。从回应公众关注和城市电磁规划出发,建议今后可利用车载巡测监测加强时域和频域的监测。 相似文献
2.
Maie Bachmann Maksim Säkki Jaan Kalda Jaanus Lass Viiu Tuulik Hiie Hinrikus 《The Environmentalist》2005,25(2-4):165-171
Summary This study focuses on discrimination of changes, produced by low-level microwave exposure in intensity and time variability
of the human EEG at rest. The power spectral density (PSD) method and nonlinear scaling analysis of the length distribution
of low variability periods (LDLVP) were selected for analysis of the EEG signal. During the study, 19 healthy volunteers were
exposed to a microwave (450 MHz) of 217 Hz frequency on-off modulation. The field power density at the scalp was 0.16 mW/cm2. The experimental protocol consisted of ten cycles of repetitive microwave exposure. Signals from frontal, temporal, parietal
and occipital EEG channels on EEG theta, alpha and beta rhythms were analysed. Exposure to microwave causes average increase
of EEG activity. LDLVP analysis discriminated significant effect in time variability for 2 subjects (11%). PSD method detected
significant changes in intensity for 4 subjects (21%). The effect of low-level microwave exposure is stronger on EEG beta
rhythm in temporal and parietal regions of the human brain. 相似文献
3.
Chiyoji Ohkubo Hideyuki Okano Akira Ushiyama Hiroshi Masuda 《The Environmentalist》2007,27(4):395-402
Authors review the importance of studying the effects of electromagnetic fields (EMF) on microcirculatory system, especially
in respect of possibility that vasculature may have direct and indirect role in interaction of static magnetic fields (SMF).
We outline the physiological importance of microcirculation and relatively new methods of evaluation technique in vivo and
explain in details the local and/or whole body exposure effects of SMF with␣range of 0.3–180 mT, power frequency EMF with
range of 0.1–30 mT and microwaves at 1.5 GHz with range 0.08–8 W/kg brain average specific absorption rate (SAR) on microcirculatory
systems in different tissues in experimental animals. 相似文献
4.
In the recent years concerns whether exposure to electromagnetic fields (EMF) from base station antennae can cause adverse
health effects are grown. Great attention is paid on risk of EMF exposure to people living in a close proximity of base stations.
In this issue, a point of interest is the personnel mounting, adjusting and maintaining base stations. Their working tasks
require stay in high EMF levels’ conditions. There are only few studies concerning this specific occupational group. The results
from our previous investigation (COST 281—Graz, 2006) show that in many cases on performing some specific tasks operators
are overexposed according to our national legislation, and ICNIRP guidelines. Here, we present an extended study covering
more base stations and more precise scenario for performed tasks and working positions. Results of exposure assessment are
presented. They include energetic load calculations on the basis of Bulgarian national legislation, and the corresponding
SAR values. Data are used to determine permissible time duration for each particular work operation and served as a base for
limiting the exposure and proposal for protective measures for the personnel. 相似文献
5.
Maie Bachmann Ruth Tomson Jaan Kalda Maksim Säkki Jaanus Lass Viiu Tuulik Hiie Hinrikus 《The Environmentalist》2007,27(4):511-517
This study was aimed to investigate the changes in the human electroencephalographic (EEG) signal caused by modulated low-level
microwaves. The 450 MHz microwave exposure modulated at 40 Hz and 70 Hz frequencies was applied to a group of 15 volunteers.
The field power density at the scalp was 0.16 mW/cm2. Ten cycles of the exposure (1 min on and 1 min off) at both modulation frequencies were applied. Analysis of the EEG signal
was performed using three different methods: nonlinear method of scaling analysis for length distribution of low variability
periods (LDLVP), relative changes in EEG energy (S-parameter) and beta ratio (H-parameter). The analysis revealed significant changes caused by microwave for the whole group (H-parameter method). The exposure caused increase of the EEG beta power (S-parameter method). Statistically significant changes in EEG were detected for four subjects (26.7%) at 40 Hz modulation frequency
(LDLVP method). 相似文献
6.
J. J. M. Cuppen G. F. Wiegertjes H. W. J. Lobee H. F. J. Savelkoul M. A. Elmusharaf A. C. Beynen H. N. A. Grooten W. Smink 《The Environmentalist》2007,27(4):577-583
A hypothesis is proposed how Low Frequency Electromagnetic Field (LF EMF) exposure can stimulate an immune response, based
on recent insights in immunology. We hypothesize that the Immunent EMF treatment induces mild stress to cells, which then
produce cytokines that function as alarms or so called danger signals for the immune system. In this way EMF treatment takes
the place of multiplying pathogens, and the damage these cause, in the triggering of an immune response. In a first series
of experiments in␣vitro common carp head kidney-derived phagocytes were used to determine ROS production as a measure for
immune activation. Exposure to LF EMF signals (200–5,000 Hz) at 5 μT or 1.5 mT led to 42 or 33% increase in immune activity,
respectively, compared to negative control values. EMF could also additionally stimulate chemically pre-stimulated samples
up to 18% (5 μT) or 22% (1.5 mT). Significance of increase in ROS production in the total series was: p < 0.0001. In a second series of experiments in␣vitro commercial goldfish were used. Groups of fish were housed under equal
conditions in at least four control tanks and 8–16 EMF-exposed tanks. Exposure was done with a predominantly vertical field
at field strengths (rms) between 0.15 and 50 μT. Without treatment mortality was about 50% after 18 days, while the treatment
at 5 μT reduced it to 20% on average. At field strengths 0.15, 0.5, 1.5, 5, 15 and 50 μT an equally strong effect was found.
Reducing the field strength to 0.05, 0.06, 0.01 and 0.003 μT showed a gradually decreasing effect, which only at 0.003 μT
is no longer statistically significant. Finally, in␣vitro experiments were done with 560 commercial broiler chickens exposed
to infection pressure from coccidiosis. EMF exposure at 6.5 μT reduced intestinal lesions by 40% and improved feed conversion
by 8%. 相似文献
7.
Electromagnetic fields exposure assessment methodology is briefly presented. The basic problems defined for the practical
use of electromagnetic fields measurements and numerical calculations carried out for workers exposure assessment in real
occupational situations are discussed. The examples of data from real workplace are presented, focusing: spatial distribution
of electromagnetic fields affecting worker’s body, complex characteristics of the frequency content, workers activities/moving
in the workplace, field impedance, etc. The situation when the use of calculations is required is discussed. The basic requirements
for workers exposure assessment protocols are presented. The possible range of the use of internal and external measures of
exposure level is also discussed. 相似文献
8.
Karol Bednarek 《International journal of occupational safety and ergonomics》2013,19(3):357-368
The paper presents an analysis of the effect of magnetic fields of power frequency generated by heavy-current electric equipment on the environment. The results of computation and measurements of the magnetic field in the vicinity of power busducts are included. Possible hazards are considered that result from the effects of the magnetic field on workers present in the vicinity of busducts as well as secondary hazards caused by the degrading effect of the magnetic field on ferromagnetic structural materials (in reinforced concrete structures). Attention is given to an ergonomic aspect of interaction of the magnetic field with cathode ray tube computer monitors (annoying oscillation of the image). 相似文献
9.
Maria G Ioannides Peter J. Papadopoulos Eugenia Dimitropoulou 《International journal of occupational safety and ergonomics》2013,19(1):87-100
A system consisting of an electric machine and a human body is studied and the resulting electric field is predicted. A 3-phase induction machine operating at full load is modeled considering its geometry, windings, and materials. A human model is also constructed approximating its geometry and the electric properties of tissues. Using the finite element technique the electric field distribution in the human body is determinedfor a distance of 1 and 5 m from the machine and its effects are studied. Particularly, electric field potential variations are determined at specific points inside the human body and for these points the electric field intensity is computed and compared to the limit values for exposure according to international standards. 相似文献
10.
This study is aimed to clarify whether effect of low-level microwave radiation on human brain differs at different modulation
frequencies. Resting EEG recordings were done on different groups of healthy volunteers. The 450 MHz microwave radiation modulated
at 40 and 70 Hz (15 subjects) and 217 and 1,000 Hz (19 subjects) frequencies was applied. The results of our previous study
at 7, 14 and 21 Hz modulation were included into analysis. Ten cycles of the exposure (1 min off and 1 min on) at each fixed
modulation frequencies were applied. The field power density at the scalp was always 0.16 mW/cm2. Our results showed that microwave exposure increased the EEG energy at EEG frequencies lower or close to the modulation
frequency. No effect was detected at EEG frequencies higher than the modulation frequency. Statistically significant changes
were caused by exposure in the EEG alpha and beta frequency bands; no significant effect was detected in the theta band. Our
results suggest that telecommunication devices with complex spectrum of modulation frequencies like mobile phone can affect
all human EEG frequency bands. 相似文献