Scenarios approach to the electromagnetic exposure: the case study of a train compartment.
Paffi A, Apollonio F, Pinto R, Liberti M. cenarios approach to the electromagnetic exposure: the case study of a train compartment. Biomed Res Int. 2015;2015:869895. doi: 10.1155/2015/869895. Epub 2015 Feb 23.
Previous studies identified the train compartment as the place where people can experience the highest exposure levels (still below the international guideline limits) to electromagnetic fields in the radiofrequency range. Here a possible scenario of a train compartment has been reproduced and characterized, both numerically and experimentally. A good agreement between the simulated electric field distributions and measurements has been found. Results indicate that the higher values of exposure in specific positions inside the train compartment depend on the number of active cell phones, the bad coverage condition, the cell orientation, and the presence of metallic walls. This study shows that the proposed approach, based on the scenarios characterization, may efficiently support the assessment of the individual electromagnetic exposure.
The huge diffusion of communication technologies based on radiofrequency (RF) electromagnetic (EM) fields, such as mobile communications (GSM, UMTS) and wireless data transfer (Wi-Fi, Wi-Max, Bluetooth, ZigBee, etc.), and their massive use in crowded environments, where people last for long time periods, as schools, hospitals, offices, and transportation means, have led to concern on possible health effects of this kind of low-level multiple exposure.
... a typical train compartment has been chosen as an interesting case study; it has been reproduced and the and fields inside have been evaluated both numerically and experimentally. The choice of such a scenario is related to the extensive experimental study of , where the train has been shown as the location where the highest mean value of exposure (still well below international guideline limits) is measured. Although different EM sources are likely to be contemporarily present inside the train, the main contribution is attributable to mobile phone handsets , especially those based on the GSM protocol, that emit the highest power levels . In particular, the higher density of mobile phone users, the bad coverage conditions often experienced during a train journey, and the presence of reflecting metallic walls could be the causes of such higher exposure levels.
To reproduce worst-case exposure conditions, the GSM technology was chosen, transmitting higher power levels with respect to the UMTS . The sources were four cell phones, GSM900 (two Motorola Timeport and two Nokia 6310), placed on a wooden table, 80 cm high, at a distance of 50 cm from each other, as in Figure 1. The cell phones, referred to as #1, #2, #3, and #4, transmitted at 900 MHz singularly or contemporarily, either at the maximum of their power (peak power: 2 W), by using controlled SIM cards, or in standard transmission conditions (average power: 250 mW). The maximum power transmission was set to simulate a bad coverage condition often experienced during a train journey.
The same train scenario was simulated using CST Microwave Studio 2010.
Results of this study show a good agreement between simulated and measured E fields at the measurement points; thus the simulated scenario has been used to identify worst-case conditions (the presence of metallic walls), which have been successively implemented in laboratory.
Numerical and experimental results confirm that while remaining below the limits imposed by the international regulations , the individual exposure in the train may significantly increase due to the bad coverage condition, the high number of cell phones which are contemporarily transmitting, and the presence of metallic walls. In particular the increases of the E field caused by the bad coverage, the four cell phones contemporarily transmitting, and the presence of the metallic walls are in the order of 6, 10, and 4 dB, respectively.
Secondhand Exposure to Cell Phone Radiation: An Emerging Public Health Problem?
Joel M. Moskowitz, Ph.D., Director
Center for Family and Community Health
School of Public Health
University of California, Berkeley
Electromagnetic Radiation Safety
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