Power density measurements and calculation were made for 20 mobile phone microcell base stations (typical output power 1-3 watts and separation distances of 300-1000 meters) and picocell base stations (typical output power in milliwatts and localized to cover discrete areas inside buildings, airport terminals, trains, etc) to see if public exposures might exceed current ICNIRP guidelines while standing on the ground at any of the sites. Minimal separation distances to maintain compliance ranged from 0.1 to 0.8 meters. Measured exposures in locations where the general public might stand were generally between 0.002-2% of the ICNIRP reference level, with the highest at 8.6% of the ICNIRP reference level. The authors conclude, members of the general public would not be exposed in excess of the ICNIRP guidelines while standing on the ground at any of the sites. In a related study, occupational exposures to RF (124 complete exposure records from 40 different sites in the UK, including VHF & UHF sites, mobile phone base stations, AM radio transmitters, a radar facility, and a satellite earth station) were assessed using a Narda ESM-20 'RadMan' personal monitor attached by fiber optic cable to a first generation data logger with a 2.8 second cycle (able to store up to 170 minutes of exposure time or 3624 data sets). The size of the RadMan was 3 x 6 inches (8 x 16 cm) and 9.35 ounces (265 grams). Of the 124 records, 17 came from workers operating outdoors at ground level, 31 from workers inside, and 76 from those operating at a height (on masts, towers, and mobile platforms). The personal monitor had a lower field detection limit of approximately 25 percent of the ICNIRP reference level for field strength. The RadMan logger calculated the average electric and magnetic field strengths (expressed as a percentage of the ICNIRP reference levels) over a period of 2 seconds, then used 0.8 seconds to write this information, along with the time and maximum field strength values to a non-volatile memory before starting the next cycle. An observer recorded the subject's activities in an event diary along with other relevant information, such as transmitters being shut down. Highest exposures were associated with proximity to a high-power VHF transmitters, pager base stations, or use of a receiver/transmitter device. Use of a mobile phone generally did not result in levels above the lower detection limit. Indoor sites or low-power sites (mobile phone base stations or other low-power transmitters were present) were rarely above the noise floor of the personal monitor. The results indicate that a individuals RF exposure depends largely on his task and location with respect to any high power transmitters. The authors suggest that personal monitors might be used in the future to assess occupational RF exposure for epidemiology studies.
AUTHORS' ABSTRACT: Litchfield et al. 2016 (IEEE #6551): Little is known about personal exposure to radiofrequency (RF) fields amongst employees in the telecommunications industry responsible for installing and maintaining transmitters. IARC classified RF exposure as a possible carcinogen, although evidence from occupational studies was judged to be inadequate. Hence, there is a need for improved evidence of any potentially adverse health effects amongst the workforce occupationally exposed to RF radiation. In this study, results are presented from an exposure survey using data from personal monitors used by employees in the broadcasting and telecommunication industries of the UK. These data were supplemented by spot measurements using broadband survey metres and information on daily work activities provided by employee questionnaires. The sets of real-time personal data were categorised by four types of site determined by the highest powered antenna present (high, medium or low power and ground-level sites). For measurements gathered at each type of site, the root mean square and a series of box plots were produced. Results from the daily activities diaries suggested that riggers working for radio and television broadcasters were exposed to much longer periods as compared to colleagues working for mobile operators. Combining the results from the measurements and daily activity diaries clearly demonstrate that exposures were highest for riggers working for broadcasting sites. This study demonstrates that it is feasible to carry out exposure surveys within these populations that will provide reliable estimates of exposure that can be used for epidemiological studies of occupational groups exposed to RF fields.