RESUMEN
The protection of man and his environment from undue exposure from radio frequency electromagnetic field requires identification of the location where exposures are likely to be higher than safe levels established by international safety standards. A wideband measurement with a spectrum analyzer and a log-periodic antenna in conjunction with the three-point spatial average method was used. The results ranged from 16.21 to 2907.00 mVm-1 and complied with a maximum of 1.08% of the ICNIRP reference level. Private frequency modulation (FM) sources were identified as the major source of exposure to the public with a mean value of 337.70 ± 133.70 mVm-1 against 122.30 ± 36.47 mVm-1 for the public FM transmitters. Even though the result was lower than a workplace assessment, it was, however, higher than similar works conducted in Africa and Palestine. Finally, four sensitive locations were identified for further research work.
Asunto(s)
Monitoreo de Radiación , Campos Electromagnéticos/efectos adversos , Exposición a Riesgos Ambientales/análisis , Ghana , Humanos , Ondas de Radio/efectos adversosRESUMEN
This paper describes an effort to respond to the suggestion in World Health Organization (WHO) research agenda to better quantify potential exposure levels from a range of radiofrequency (RF) sources at 200 public access locations in Ghana. Wide-band measurements were performed-with a spectrum analyser and a log-periodic antenna using three-point spatial averaging method. The overall results represented a maximum of 0.19% of the ICNIRP reference levels for public exposure. These results were generally lower than found in some previous but were 58% (2.0 dB) greater, than found in similar work conducted in the USA. Major contributing sources of RF fields were identified to be FM broadcast and mobile base station sites. Three locations with the greatest measured RF fields could represent potential areas for epidemiological studies.
Asunto(s)
Radiación Electromagnética , Exposición a Riesgos Ambientales/análisis , Monitoreo de Radiación/métodos , Ondas de Radio , Ghana , HumanosRESUMEN
The analysis of channel power and electric field strength at various locations from mobile base stations using power sensor, spectrum analyzer and log-periodic antenna revealed maximum potential exposure between the range of 61.1 and 254.7 m. Generally, the potential exposure values ranged from 0.0717 to 0.8950 mW m-2 with a maximum deviation of 22.22%. GSM900 was found to be more pronounced than GSM1800 and UMTS2100. Though the results complied with ICNIRP reference levels with a wide margin of 0.01%, it was higher than some previous work and South African mean value of 0.16 mW m-2, agreed with similar work elsewhere but lower than a global average value of 0.730 mW m-2.
Asunto(s)
Teléfono Celular , Radiación Electromagnética , Exposición a Riesgos Ambientales/análisis , Monitoreo de Radiación/instrumentación , Diseño de Equipo , GhanaRESUMEN
A radiofrequency (RF) electromagnetic radiation safety survey had been carried out at public access points in 46 towns with 76 Global Systems for Mobile communication cell sites in two major cities in Ghana. The objective was to determine the levels of RF field in residential areas, schools and market places, and compare the measured results with the guidelines set by the International Commission of Non-Ionising Radiation (ICNIRP). Measurements were made with log-periodic antenna coupled with spectrum analyzer. The results varied from 0.85 to 1.07 mW m(-2) and 0.78 to 1.19 mW m(-2) for the transmission frequencies of 900 and 1800 MHz, respectively. The result generally shows a compliance with the ICNIRP limit of 0.024 % but was 108 times higher than a similar survey carried out in Ghana 2 y ago.
Asunto(s)
Teléfono Celular , Radiación Electromagnética , Exposición a Riesgos Ambientales/análisis , Monitoreo de Radiación , Ondas de Radio , HumanosRESUMEN
A theoretical study was carried out to re-evaluate the integrity of the biological shielding of (137)Cs brachytherapy unit at the Korle Bu Teaching Hospital, Ghana, and the results were verified by measurement of the dose rates at selected locations. The primary objective was to determine the current state of protection and safety of staff and the general public. Shielding design of the brachytherapy unit at the hospital was based on postulated workload and occupancy factors of the facility. The facility has been in existence for 12 y and has accumulated operational workload data that differs from the postulated one. The results show that despite the variation in actual and postulated workloads, the dose rates were below the reference values 0.5 microSv h(-1) for public areas and 7.5 microSv h(-1) for controlled areas. These values were in the range of 0.10-0.12 microSv h(-1) for public areas and of 0.50-2.10 microSv h(-1) for controlled areas.