Personal Exposure Meters Research Articles

Effect of occupational EMF exposure from radar at two different frequency bands on plasma melatonin and serotonin levels

Objective: To delineate the effect of chronic electromagnetic field (EMF) exposure from radar on plasma melatonin and serotonin levels in occupationally exposed military personnel.Subjects and methods: A total of 166 male military personnel participated in the study out of which only 155 joined for blood draw. They were divided into three sets: Control group (n = 68), exposure group I (n = 40) exposed to 8–12 GHz and exposure group II (n = 58) working with radar at 12.5–18 GHz frequency. The three groups were further split into two groups according to their years of service (up to 10 years and > 10 years) in order to investigate the effect of years of exposure from radar. Melatonin and serotonin levels were estimated by enzyme immunoassay in fasting blood samples collected from 06:00–07:00 h. EMF measurements were recorded at different locations using Satimo EME Guard ‘Personal Exposure Meter’ and Narda ‘Broad Band Field Meter’.Results: The group I exposed population registered a minor though not significant decrease in plasma melatonin concentration while the other group II exposed population registered statistically significant decline in melatonin concentration when compared with controls. Highly significant increase in plasma serotonin levels was found in exposure group II when compared to control whereas marginal non-significant rise was also registered in exposure group I in comparison to control. Exposure in terms of length of service up to 10 years did not produce any significant effect in the indoleamine levels in both the exposure groups when they were compared with their respective control groups. Whereas, length of service greater than 10 years was observed to decrease and increase respectively the melatonin and serotonin concentration significantly in exposure group II but not in exposure group I. However, correlation test did not yield any significant association between years of service and melatonin or serotonin levels respectively in both the exposure sets I and II. No significant association was observed between melatonin and serotonin levels as well.Conclusion: The study showed the EMF ability to influence plasma melatonin and serotonin concentration in radar workers, significantly in 12.5–18 GHz range with service period greater than 10 years.

Assessment of human body influence on exposure measurements of electric field in indoor enclosures.

Personal exposure meters (PEMs) used for measuring exposure to electromagnetic fields (EMF) are typically used in epidemiological studies. As is well known, these measurement devices cause a perturbation of real EMF exposure levels due to the presence of the human body in the immediate proximity. This paper aims to model the alteration caused by the body shadow effect (BSE) in motion conditions and in indoor enclosures at the Wi-Fi frequency of 2.4 GHz. For this purpose, simulation techniques based on ray-tracing have been carried out, and their results have been verified experimentally. A good agreement exists between simulation and experimental results in terms of electric field (E-field) levels, and taking into account the cumulative distribution function (CDF) of the spatial distribution of amplitude. The Kolmogorov-Smirnov (KS) test provides a P-value greater than 0.05, in fact close to 1. It has been found that the influence of the presence of the human body can be characterized as an angle of shadow that depends on the dimensions of the indoor enclosure. The CDFs show that the E-field levels in indoor conditions follow a lognormal distribution in the absence of the human body and under the influence of BSE. In conclusion, the perturbation caused by BSE in PEMs readings cannot be compensated for by correction factors. Although the mean value is well adjusted, BSE causes changes in CDF that would require improvements in measurement protocols and in the design of measuring devices to subsequently avoid systematic errors.

Development of a subjective loudness rating scale

Objective: In an earlier study (), detailed noise exposure measurements were obtained through individual dosimetry. In this further analysis of the data we ask the question “Can the effort required to converse in noise be used to estimate the experienced A-weighted noise level?” Design: The noise levels experienced during specific activities were obtained from the analysis of dosimetry results from personal noise exposure meters worn by study participants. The measured noise levels from particular events were compared to a subjectively judged ‘loudness rating’ reported by the person wearing the dosimeter during the measured event. Study sample: Volunteers (females = 20, males = 22) between 18 and 35 years (average age = 26.8) willing to wear dosimeters and keep a simple activity log. Results: The relation between the objectively measured and the subjectively judged levels was consistent for the group over a large number of events. Conclusions: The subjective loudness rating index was shown to be a convenient tool that can be utilized for the retrospective estimation of noise levels from individual activities.

Combining near‐ and far‐field exposure for an organ‐specific and whole‐body RF‐EMF proxy for epidemiological research: A reference case

A framework for the combination of near-field (NF) and far-field (FF) radio frequency electromagnetic exposure sources to the average organ and whole-body specific absorption rates (SARs) is presented. As a reference case, values based on numerically derived SARs for whole-body and individual organs and tissues are combined with realistic exposure data, which have been collected using personal exposure meters during the Swiss Qualifex study. The framework presented can be applied to any study region where exposure data is collected by appropriate measurement equipment. Based on results derived from the data for the region of Basel, Switzerland, the relative importance of NF and FF sources to the personal exposure is examined for three different study groups. The results show that a 24-h whole-body averaged exposure of a typical mobile phone user is dominated by the use of his or her own mobile phone when a Global System for Mobile Communications (GSM) 900 or GSM 1800 phone is used. If only Universal Mobile Telecommunications System (UMTS) phones are used, the user would experience a lower exposure level on average caused by the lower average output power of UMTS phones. Data presented clearly indicate the necessity of collecting band-selective exposure data in epidemiological studies related to electromagnetic fields.

The objective-subjective assessment of noise: Young adults can estimate loudness of events and lifestyle noise

Objective: The aim of the study was to establish whether individuals can subjectively estimate: (1) the loudness of events with respect to the objectively measured noise level; and (2) the overall loudness of their daily noise exposure level. Design: Participants wore personal noise exposure meters for up to five days. During this time, participants kept diaries of daily events and estimated the loudness of these events and their overall noise exposure using 1-to-10 rating scales. Study sample: A group of 45 volunteers aged between 18 and 35 years participated in the study. Results: 86% of participants’ subjective estimates were significantly correlated with the objective noise measurements. Multiple regression showed that age, overall lifestyle noise, and diary quality were predictors of the strength of correlation observed. In addition participants’ subjective estimates of their overall noise exposure were significantly correlated with their actual average daily noise exposure. Conclusions: Results suggest that individuals can make a reasonable estimate of the loudness of events they experience and the overall level of noise they experience. These results may have significant influence for those interested in producing effective hearing health awareness programs in that individuals may be capable of assessing their own degree of hazard exposure.

Measurement setup and protocol for characterizing and testing radio frequency personal exposure meters

Body-worn radiofrequency electromagnetic field (RF-EMF) personal exposure meters (PEMs) have been increasingly used for exposure assessment in epidemiological research. However, little research on the measurement accuracy of these devices is available. In this article a novel measurement setup and a measurement protocol are presented for characterizing and testing PEMs. The whole setup and procedure is tested using two EME SPY 120 devices. The performance of the PEM was analyzed for absolute measurements in an anechoic chamber. Modulated signals representing the different services as real signals generated by appropriate testers were used. Measurement results were evaluated with respect to a root mean square detector. We found that measurement accuracy depends strongly on the carrier frequency and also on the number of occupied time slots for Time Division Multiple Access (TDMA)-based services. Thus, correction factors can only be derived if the distribution of the network configuration over the measurement time for all measurement points is available. As a result of the simplicity of the measurement setup and the straightforward measurement protocol, the possibility of fast validation leads to a higher accuracy in the characterization and testing of PEMs.

Calibration and uncertainties in personal exposure measurements of radiofrequency electromagnetic fields

In the past 5 years radiofrequency personal exposure meters have been used to characterize the exposure during daily activities. We found from calibration tests for the 12 frequency bands of the EME Spy 121 exposimeter in a Gigahertz Transverse Electromagnetic cell and an Open Area Test Site, that these measurements tend to underestimate the actual exposure. Therefore, a maximum frequency-dependent correction factor of 1.1-1.6 should be applied to the electric field. This correction factor consists of three multipliers correcting for calibration, elevation arrival angle, and influence of the body. The calibration correction factor should be determined per exposimeter, as the maximum range of response between exposimeters in a frequency band is 2.4 dB. Since the range of response for different elevation angles could reach 10.2 dB, a strict protocol for wearing the exposimeter during fieldwork should be followed to be able to compare and combine measurements made by different persons in the same microenvironments. Because the influence of the body depends on the azimuth angle of arrival, it may lead to an over- or underestimation. Thus, the body correction factor is an average over the angles and should only be applied in activities involving movement through the full 360° range of random angles of arrival.

Variability of radiofrequency exposure across days of the week: A population-based study

Although measurement of the radiofrequency (RF) exposure can today be performed with personal exposure meters, this approach would be very expensive and time-consuming for large studies, and long term measurements would require considerable commitment of the study participants. Thus, there is a need for validated exposure assessment methods that do not require individual measurements for each study participant. Among the potential predictors, one of the most amenable to being recorded adequately is the day of the week. Drawing upon an existing population-based study, our goal was therefore to assess variability of individual RF exposure across days of the week. The random sample consisted of 34 people who were supplied with a personal exposure meter for seven consecutive days, and kept a time–location–activity diary. A total of 225,414 electric field strength measurements were recorded in 12 different RF bands. Summary statistics were calculated with the robust regression on order statistics method. We found evidence for statistically significant variability of individual RF exposure across days of the week, though the relative magnitude of the differences observed was small. Larger studies are needed to validate these results and determine whether day of the week is an important determinant for inclusion in individual RF exposure prediction models that remain urgently needed to conduct epidemiological studies on potential health effects.

Statistical perturbations in personal exposure meters caused by the human body in dynamic outdoor environments

Personal exposure meters (PEM) are routinely used for the exposure assessment to radio frequency electric or magnetic fields. However, their readings are subject to errors associated with perturbations of the fields caused by the presence of the human body. This paper presents a novel analysis method for the characterization of this effect. Using ray-tracing techniques, PEM measurements have been emulated, with and without an approximation of this shadowing effect. In particular, the Global System for Mobile Communication mobile phone frequency band was chosen for its ubiquity and, specifically, we considered the case where the subject is walking outdoors in a relatively open area. These simulations have been contrasted with real PEM measurements in a 35-min walk. Results show a good agreement in terms of root mean square error and E-field cumulative distribution function (CDF), with a significant improvement when the shadowing effect is taken into account. In particular, the Kolmogorov-Smirnov (KS) test provides a P-value of 0.05 when considering the shadowing effect, versus a P-value of 10⁻¹⁴ when this effect is ignored. In addition, although the E-field levels in the absence of a human body have been found to follow a Nakagami distribution, a lognormal distribution fits the statistics of the PEM values better than the Nakagami distribution. As a conclusion, although the mean could be adjusted by using correction factors, there are also other changes in the CDF that require particular attention due to the shadowing effect because they might lead to a systematic error.

Occupational and Residential Exposures to ELF Magnetic Fields Over a 24-h Period Among a Sample of Urban Populations in Korea

The objective of this survey is to characterize the extremely low frequency (ELF) personal magnetic field (MF) exposure of the general population in Korea. This is the first-ever personal MF exposure survey done in Korea. The participants of the survey on MF exposure were randomly selected by occupation. The survey was conducted as follows: study participants wore an MF meter for about 25-28 h, and the exposure data were stored in the meter every 4 s. The personal MF exposure meter that was used for this survey was EMDEX-LITE, made by Enertech Consultants, Inc., USA. The participants were asked to record their activities so that MF exposure can be evaluated for a 24-h period. The personal MF exposure survey has been conducted for about four years, and the total number of participants was 466. To get the 24-h exposure data is one of the main purposes of this survey. The survey also provided an opportunity to analyze exposures corresponding to different types of activities. The exposure was analyzed in separate periods corresponding to the following activities: the entire 24-h period, in bed, at work, and by occupation. Therefore, the database was utilized to analyze the present status of personal MF exposure.

Comparison of personal radio frequency electromagnetic field exposure in different urban areas across Europe

Background Only limited data are available on personal radio frequency electromagnetic field (RF-EMF) exposure in everyday life. Several European countries performed measurement studies in this area of research. However, a comparison between countries regarding typical exposure levels is lacking. Objectives To compare for the first time mean exposure levels and contributions of different sources in specific environments between different European countries. Methods In five countries (Belgium, Switzerland, Slovenia, Hungary, and the Netherlands), measurement studies were performed using the same personal exposure meters. The pooled data were analyzed using the robust regression on order statistics (ROS) method in order to allow for data below the detection limit. Mean exposure levels were compared between different microenvironments such as homes, public transports, or outdoor. Results Exposure levels were of the same order of magnitude in all countries and well below the international exposure limits. In all countries except for the Netherlands, the highest total exposure was measured in transport vehicles (trains, car, and busses), mainly due to radiation from mobile phone handsets (up to 97%). Exposure levels were in general lower in private houses or flats than in offices and outdoors. At home, contributions from various sources were quite different between countries. Conclusions Highest total personal RF-EMF exposure was measured inside transport vehicles and was well below international exposure limits. This is mainly due to mobile phone handsets. Mobile telecommunication can be considered to be the main contribution to total RF-EMF exposure in all microenvironments.

Classification of personal exposure to radio frequency electromagnetic fields (RF-EMF) for epidemiological research: Evaluation of different exposure assessment methods

The use of personal exposure meters (exposimeters) has been recommended for measuring personal exposure to radio frequency electromagnetic fields (RF-EMF) from environmental far-field sources in everyday life. However, it is unclear to what extent exposimeter readings are affected by measurements taken when personal mobile and cordless phones are used. In addition, the use of exposimeters in large epidemiological studies is limited due to high costs and large effort for study participants. In the current analysis we aimed to investigate the impact of personal phone use on exposimeter readings and to evaluate different exposure assessment methods potentially useful in epidemiological studies. We collected personal exposimeter measurements during one week and diary data from 166 study participants. Moreover, we collected spot measurements in the participants' bedrooms and data on self-estimated exposure, assessed residential exposure to fixed site transmitters by calculating the geo-coded distance and mean RF-EMF from a geospatial propagation model, and developed an exposure prediction model based on the propagation model and exposure relevant behavior. The mean personal exposure was 0.13 mW/m 2, when measurements during personal phone calls were excluded and 0.15 mW/m 2, when such measurements were included. The Spearman correlation with personal exposure (without personal phone calls) was 0.42 (95%-CI: 0.29 to 0.55) for the spot measurements, − 0.03 (95%-CI: − 0.18 to 0.12) for the geo-coded distance, 0.28 (95%-CI: 0.14 to 0.42) for the geospatial propagation model, 0.50 (95%-CI: 0.37 to 0.61) for the full exposure prediction model and 0.06 (95%-CI: − 0.10 to 0.21) for self-estimated exposure. In conclusion, personal exposure measured with exposimeters correlated best with the full exposure prediction model and spot measurements. Self-estimated exposure and geo-coded distance turned out to be poor surrogates for personal exposure.

Estimation of whole‐body SAR from electromagnetic fields using personal exposure meters

In this article, personal electromagnetic field measurements are converted into whole-body specific absorption rates for exposure of the general public. Whole-body SAR values calculated from personal exposure meter data are compared for different human spheroid phantoms: the highest SAR values (at 950 MHz) are obtained for the 1-year-old child (99th percentile of 17.9 microW/kg for electric field strength of 0.36 V/m), followed by the 5-year-old child, 10-year-old child, average woman, and average man. For the 1-year-old child, whole-body SAR values due to 9 different radiofrequency sources (FM, DAB, TETRA, TV, GSM900 DL, GSM1800 DL, DECT, UMTS DL, WiFi) are determined for 15 different scenarios. An SAR matrix for 15 different exposure scenarios and 9 sources is provided with the personal field exposure matrix. Highest 95th percentiles of the whole-body SAR are equal to 7.9 microW/kg (0.36 V/m, GSM900 DL), 5.8 microW/kg (0.26 V/m, DAB/TV), and 7.1 microW/kg (0.41 V/m, DECT) for the 1-year-old child, with a maximal total whole-body SAR of 11.5 microW/kg (0.48 V/m) due to all 9 sources. All values are below the basic restriction of 0.08 W/kg for the general public. 95th percentiles of whole-body SAR per V/m are equal to 60.1, 87.9, and 42.7 microW/kg for GSM900, DAB/TV, and DECT sources, respectively. Functions of the SAR versus measured electric fields are provided for the different phantoms and frequencies, enabling epidemiological and dosimetric studies to make an analysis in combination with both electric field and actual whole-body SAR.

Radiofrequency exposure in the French general population: Band, time, location and activity variability

Information on the exposure of individual persons to radiofrequency (RF) fields is scarce, although such data are crucial in order to develop a suitable exposure assessment method, and frame the hypothesis and design of future epidemiological studies. The main goal of this survey is to assess individual RF exposure on a population basis, while clarifying the relative contribution of different sources to the total exposure. A total of 377 randomly selected people were analyzed. Each participant was supplied with a personal exposure meter for 24-hour measurements (weekday), and kept a time–location–activity diary. Electric field strengths were recorded in 12 different RF bands every 13 s. Summary statistics were calculated with the robust regression on order statistics method. Most of the time, recorded field strengths were not detectable with the exposure meter. Total field, cordless phones, WiFi-microwave, and FM transmitters stood apart with a proportion above the detection threshold of 46.6%, 17.2%, 14.1%, and 11.0%, respectively. The total field mean value was 0.201 V/m, higher in urban areas, during daytime, among adults, and when moving. When focusing on specific channels, the highest mean exposure resulted from FM sources (0.044 V/m), followed by WiFi-microwaves (0.038 V/m), cordless phones (0.037 V/m), and mobile phones (UMTS: 0.036 V/m, UMTS: 0.037 V/m). Various factors, however, contributed to a high variability in RF exposure assessment. These population-based estimates should therefore be confirmed by further surveys to better characterize the exposure situation in different microenvironments.

Temporal and spatial variability of personal exposure to radio frequency electromagnetic fields

Little is known about the population's exposure to radio frequency electromagnetic fields (RF-EMF) in industrialized countries. To examine levels of exposure and the importance of different RF-EMF sources and settings in a sample of volunteers living in a Swiss city. RF-EMF exposure of 166 volunteers from Basel, Switzerland, was measured with personal exposure meters (exposimeters). Participants carried an exposimeter for 1 week (two separate weeks in 32 participants) and completed an activity diary. Mean values were calculated using the robust regression on order statistics (ROS) method. Mean weekly exposure to all RF-EMF sources was 0.13 mW/m(2) (0.22 V/m) (range of individual means 0.014-0.881 mW/m(2)). Exposure was mainly due to mobile phone base stations (32.0%), mobile phone handsets (29.1%) and digital enhanced cordless telecommunications (DECT) phones (22.7%). Persons owning a DECT phone (total mean 0.15 mW/m(2)) or mobile phone (0.14 mW/m(2)) were exposed more than those not owning a DECT or mobile phone (0.10 mW/m(2)). Mean values were highest in trains (1.16 mW/m(2)), airports (0.74 mW/m(2)) and tramways or buses (0.36 mW/m(2)), and higher during daytime (0.16 mW/m(2)) than nighttime (0.08 mW/m(2)). The Spearman correlation coefficient between mean exposure in the first and second week was 0.61. Exposure to RF-EMF varied considerably between persons and locations but was fairly consistent within persons. Mobile phone handsets, mobile phone base stations and cordless phones were important sources of exposure in urban Switzerland.

Residential exposure to radiofrequency fields from mobile phone base stations, and broadcast transmitters: a population-based survey with personal meter

Objectives:Both the public perceptions, and most published epidemiologic studies, rely on the assumption that the distance of a particular residence from a base station or a broadcast transmitter is an...

CHARACTERIZATION OF PERSONAL RF ELECTROMAGNETIC FIELD EXPOSURE AND ACTUAL ABSORPTION FOR THE GENERAL PUBLIC

In this paper, personal electromagnetic field exposure of the general public due to 12 different radiofrequency sources is characterized. Twenty-eight different realistic exposure scenarios based upon time, environment, activity, and location have been defined and a relevant number of measurements were performed with a personal exposure meter. Indoor exposure in office environments can be higher than outdoor exposure: 95th percentiles of field values due to WiFi ranged from 0.36 to 0.58 V m(-1), and for DECT values of 0.33 V m(-1) were measured. The downlink signals of GSM and DCS caused the highest outdoor exposures up to 0.52 V m(-1). The highest total field exposure occurred for mobile scenarios (inside a train or bus) from uplink signals of GSM and DCS (e.g., mobile phones) due to changing environmental conditions, handovers, and higher required transmitted signals from mobile phones due to penetration through windows while moving. A method to relate the exposure to the actual whole-body absorption in the human body is proposed. An application is shown where the actual absorption in a human body model due to a GSM downlink signal is determined. Fiftieth, 95th, and 99 th percentiles of the whole-body specific absorption rate (SAR) due to this GSM signal of 0.58 microW kg(-1), 2.08 microW kg(-1), and 5.01 microW kg(-1) are obtained for a 95th percentile of 0.26 V m(-1). A practical usable function is proposed for the relation between the whole-body SAR and the electric fields. The methodology of this paper enables epidemiological studies to make an analysis in combination with both electric field and actual whole-body SAR values and to compare exposure with basic restrictions.

A new electronic personal exposure meter for radon gas

A new electronic meter for personal radon exposures was developed and several prototypes were built. The exposure meter is optimized with respect to short-term (days) and long-term ( > 1 y ) measurements of indoor radon concentrations and personal radon exposure. The exposure meter records measured concentration levels in adjustable time intervals allowing a time resolved analysis.

Potential exposure assessment errors associated with body‐worn RF dosimeters

Personal exposure meters for assessing exposure to RF electric or magnetic fields are subject to errors associated with perturbations of the fields by the presence of the human body. Although these alterations are complex they are not completely unpredictable. This article concludes that this error in a common worst-case scenario could reach up to 30 dB and therefore is of concern for exposure assessment. We present several guidelines to address this issue and a useful insight into the overall problem based on finite-difference time-domain simulations and experimental verification.

Practical considerations in the verification of personal sound exposure meters

This paper analyses the problems that appear when calibration or verification of personal sound exposure meters is done following the recommendations of IEC 61252. The tests recommended in the standard to verify the characteristics of such instruments are discussed and alternative procedures are proposed to solve the problems detected. The two main problems detected are related to the duration of the process, which has a direct effect on the verification cost, and the measurement uncertainty. The use of procedures based on measurement modes that are not dependent on integration times, such as when measuring sound pressure level, is recommended whenever possible.