This study presents data related to GSM (Global System for Mobile Communications) cellular phone radiation resulting from antenna sites and towers inside residential areas in Germany. A statistical evaluation of over 200 representative high frequency field measurements is presented for the years 2001 and 2002.
Measurements were conducted at different distances and directions using a frequency selective spectrum analysis to obtain only GSM power densities following the Swiss guideline for GSM cellular phone radiation measurements. Derived from this data, GSM cellular phone tower radiation is dominant in comparison to FM radio or TV emissions. The median power density was found to be in the range of 200 µW/m2 with the maximum level exceeding 100,000 µW/m2. A total of 25 percent of the power densities exceeds 1,000 µW/m2, which has been suggested to be the average threshold value for non-thermal biological effects. Two of the most important factors are the distance and the direct line of sight to the antenna site. At the typical residential cell tower distance of about 250 m in cities, with direct line of sight, the observed levels are in the range of 200 µW/m2.
The results show that, especially for future cellular UMTS (Universal Mobile Telecommunications System) applications, there are several options to minimize additional HF radiation exposures for the population and reduce the potential risk for harmful exposures.
The GSM technology of wireless communication produces constant pulsed microwave radiation. The cellular base stations are transmitting continuously even when nobody is using the phone. We know from a variety of scientific studies, that significant biological effects result from the non-thermal effects of extremely periodic – pulsed – HF-radiation as are utilized in the most common modern digital cellular and cordless phone systems in Germany and round the world. Official international and national standards and safety guidelines (based on ICNIRP recommendations) are still only taking into account the risk of thermal effects of high energy HF-radiation.
Most of the official HF public exposure measurements are conducted to observe the percentage of the current standard with only broadband – not frequency selective – measurements. Only in very few cases one or more percent of the (thermal) guideline value is reached or exceeded close to antenna sites. Exposure recommendations based on non-thermal effects are by far lower by many magnitudes. Frequency selective measurements are necessary to observe the cellular base station downlink frequencies and differentiate from other radiation sources as FM radio or TV transmitters. Therefore, very limited information is available on the exposure to cellular base station radiation in residential areas at different distances and directions to antenna sites.
The objective of this field study was to collect measurement data, statistical evaluation, documentation and exposure assessment for cellular phone tower radiation in Germany. Measurements were conducted at different distances and directions, inside and outside of representative public and residential buildings. Frequency selective spectrum analysis was used to obtain GSM power densities following the current recommendations for GSM cellular phone radiation measurements.
Methods and Results
Power density measurements were performed with an Advantest R3131 spectrum analyzer (Rohde & Schwarz) and a calibrated periodic logarithmic log.per. antenna USLP 9143 (Schwarzbeck). The power density measurements were conducted under real-life conditions and only downlink frequencies of the GSM cellular base stations were measured. The antenna was directed in various orientations in order to receive local maximum power densities by peak hold measurements in respect to orientation, polarization, reflection, and interference. For each narrow band region of interest (GSM900, GSM1800) data collection was conducted for 3 x 1 min. scanning time. All measurements were conducted following VDB guideline (VDB 2002) and the Swiss BUWAL guideline (BUWAL 2002). The power density levels are given in µW/m2 (microwatt per square meter). 1 µW/m2 equals 0.1 nW/cm2 (nanowatt per square centimeter). The limit of detection was 0.001 – 0.002 µW/m2 (-70 dBm) per channel power density. The extended error is ± 45 % (BUWAL 2002).
The measurements included a total of 272 locations (132 inside / 140 outside), power densities of all GSM downlink organization channels per location, summation to the maximum possible total power density, and documentation of the distance and the line of sight to the dominating antenna site. Distance profiles were taken for selected locations and different antenna heights and positions. In addition, data for FM radio, TV, DECT cordless phone and other significant HF sources were collected for comparison. Figure 1 shows a typical HF spectrum analysis overview of a location in close vicinity to an antenna site.
Figure 1: HF spectrum analysis – overview
Statistical Data and Percentiles
The percentiles for the observed power density values are presented in Table 1. Including all locations, the median distance was 150 meter (450 feet), which is in the range of typical residential distances to GSM base stations in larger cities. The 20th percentile value is 10 µW/m2 and can be considered as residential background GSM radiation level. The 50th percentile value is found at 200 µW/m2 (median). The 95th percentile is observed at 6,300 µW/m2 and can be considered as a significant exposure radiation level. The maximum value of 103,000 µW/m2 was found in a residential building in the 4th floor in line of sight and in the same height to the antenna site at a horizontal distance of 30 meter. In addition, data sets for line of sight, without line of sight, inside and outside locations were calculated separately. (see Table 1 and Figure 2 for further details)
Table 1: GSM cellular tower base station power density levels – percentiles
Number of measurements (n)
Distance in meter (median)
Power density in µW/m2
50th percentile (median)
Comparison of Standard Threshold Values and Recommendations
Total Power Density
Standards, GSM1800/GSM1900/UMTS/DECT (e.g.)
FCC/ANSI – USA
Germany, England, Finland and Japan
Switzerland and Italy
Recommendations / References (e.g.)
Ecolog Study, Germany (Ecolog 2000)
Cellular tower radiation – significant exposure level, 95th percentile (this study)
Salzburg, Austria (Resolution 2000)
Cellular tower radiation – median level, 50th percentile (this study)
High exposure, Oeko-Test (OekoTest 2001)
EU Parliament (STOA 2001)
Cellular tower radiation – background level, 20th percentile (this study)
Low exposure, Oeko-Test (Oeko Test 2001)
Nighttime exposure, Baubiology Standard (SBM 2000)
Successful communication with GSM mobile phone, system coverage requirements
Natural cosmic microwave radiation (Maes 2000)