Exposure of the general public to RF electromagnetic fields

Transcription

1 Workshop "Acute Health Impairment", Dec 12-13, 2006 Exposure of the general public to RF electromagnetic fields Dr. Christian Bornkessel, IMST GmbH, Carl-Friedrich-Gauss-St. 2, D Kamp-Lintfort IMST GmbH Carl-Friedrich-Gauß-Strasse Kamp-Lintfort Tel.: Fax: contact@imst.de

2 Outline RF sources and their exposure - relevant exposures in everyday life - focus on general public exposure - exposure results with special regard to DMF studies Personal exposure meters (Dosimeter) - available dosimeters - typical results Folie 2

3 Classification of relevant RF sources Installation type Fixed Mobile phone base stations TV broadcast transmitters Radio broadcast transmitters Mobile Mobile phones DECT phones WLAN applications Folie 3

4 Classification of relevant RF sources Installation place Outdoor Mobile phone base stations TV broadcast transmitters Radio broadcast transmitters Household Mobile phones DECT phones WLAN applications Folie 4

5 Classification of relevant RF sources Distance Far field Mobile phone base stations TV broadcast transmitters Radio broadcast transmitters Close to body or body contact Mobile phones DECT phones WLAN applications Folie 5

6 Mobile phone base stations Frequency: MHz (GSM 900) MHz (GSM 1800) MHz (UMTS) Transmit Power: - typ W/channel/sector W (EIRP)/channel/sector Transmitter:- ~85,000 stations in Germany Coverage: Distance to Persons: Remarks: m 20 km - far field - power control Folie 6

7 Projects supported within DMF Development of measurement and calculation methods for the determination of the public exposure due to electromagnetic fields in the vicinity of mobile phone base stations (IMST) Determination of the exposure of groups of people that will be investigated within the scope of the project "Cross sectional study for ascertainment and assessment of possible adverse effects by fields of mobile phone base stations" (ECOLOG) Determination of the real field distribution from high frequency electromagnetic fields near UMTS transmitters (IMST+EM Institute) BS Folie 7

8 Extrapolated exposure (IMST+EM-Institute) 100,000 10,000 GSM UMTS 1.6 % limit 5.4 V/m 78.3 mw/m² 0.7 % limit 5.1 V/m 69.3 mw/m² power density in % of limit 1,000 0,100 0,010 0,001 0, % V/m 0.03 µw/m² scenario no % 0.01 V/m 0.1 µw/m² Folie 8

9 Extrapolated exposure near base stations (2) 100,000 10,000 GSM UMTS high mounted antennas power density in % of limit 1,000 0,100 0,010 0,001 0, scenario no. Folie 9 low mounted antennas low mounted antennas (micro cell / indoor scenarios)

10 Folie 10 GSM 900 antenna pattern UMTS antenna pattern measurement point no electric field strength [% of limit] GSM > UMTS at 85 % of all points (compared to limit) 12 UMTS GSM 14 Comparison GSM/UMTS

11 Small scale field variation in space Measurement: GSM 900 and UMTS Simulation: GSM electric field strength [dbµv/m] GSM 900 UMTS place [cm] Small scale variations (fast fading) especially at indoor scenarios due to multipath propagation Variations of 10 db and more Folie 11

12 Small and large scale variations in time Station A: GSM 24 hours Station B: GSM 7 days electric field strength [V/m] 3,5 3 2,5 2 1,5 electric field strength [V/m] :00 16:00 20:00 0:00 4:00 8:00 12:00 time 1.0 Tu We Th Fr Sa Su Mo Tu day Small and large scale variations due to traffic load (power control) Folie 12

13 Time and space averaged exposure (ECOLOG) Exposure inside buildings 1 m x 1 m grid 5 point grid Time and space averaging, no focus on "maximal exposed areas" Exposure 10-1,000 times smaller than measured under worst case aspects Folie 13 Source: ECOLOG Institute

14 Mobile phones Frequency: MHz (GSM 900) MHz (GSM 1800) MHz (UMTS) Source: Transmit Power: Number: Coverage: Distance to Persons: Remarks: - up to 250 mw time averaged - up to 2 W peak - ~80 million - up to 20 km - body contact - power control Folie 14

15 Folie 15 typ % limit consumption SAR is measured under "worst case" conditions (maximal transmit power) Mobile phone Nokia N93 Sony Ericsson W550i Nokia E50 Nokia 6230i Sony Ericsson W700i Nokia 3250 Sony Ericsson K750i Sony Ericsson W810i Nokia 6233 Nokia 6270 Nokia 6131 Nokia N73 Sony Ericsson K510i Sony Ericsson W800i Nokia 6125 LG U8290 Samsung SGH-E770 Samsung SGH-X700 Siemens S75 Motorola ROKR Sagem my 700X BenQ-Siemens C81 BenQ-Siemens EF81 Motorola L7 Motorola V3x Pantech GU-1100 Palm Treo 650 0,2 0 SAR value 10g [W/kg] 0,6 0,4 0,8 1 1,4 1,2 1,8 1,6 2 SAR-Measurements

16 Projects supported within DMF Determination of the specific absorption rate (SAR values) occurring during dayto-day mobile phone use (Telecom-Consult) Determination of the real exposure from using mobile phones in partially shielded rooms as compared to exposure under optimal conditions outdoors (Telecom-Consult) Folie 16 Source: Telecom-Consult

17 Exposure results: Averaged exposure Inside a room, Nokia 6150 Inside a train, Nokia 6110/6150 On average % of "worst case" SAR, depending on coverage and cell changes Further reduction due to DTX Position change Folie 17 Source: Telecom-Consult

18 TV Broadcast Frequency: MHz (analogue) MHz (analogue, digital) MHz (analogue, digital) MHz (digital) Transmit Power: - up to several 100 kw (ERP) per site Transmitter:- typ main transmitters each federal state (Germany) Wendelstein Coverage: Distance to Persons: - up to 60 km - far field Folie 18

19 Projects supported within DMF Determination of exposure to the population living near digital radio and television transmitters (IMST+EM Institute) Folie 19

20 Exposure to Analogue TV and DVB-T (same region) Analogue TV DVB-T power density [% of limit] 1 0,1 0,01 0,001 0,0001 power density [% of limit] 1 0,1 0,01 0,001 0,0001 0, , , , measurement point measurement point More than 300 measurement points in Nuremberg and Munich region Points statistically distributed; proportional to population density Measurements before (A-TV) and after (DVB-T) switching to DVB-T Exposures mostly below % of limit Folie 20

21 FM radio and DAB Frequency: MHz (FM radio) MHz (DAB) MHz (DAB) Transmit Power: - FM: typ. several 10 kw (ERP) DAB: typ. several kw per site Transmitter:- several 100 (Germany) Coverage: Distance to Persons: - up to 60 km - far field Folie 21

22 Projects supported within DMF Determination of exposure to the population living near digital radio and television transmitters (IMST+EM Institute) Düsseldorf Hamburg Berlin Stuttgart München Folie 22

23 Exposure to FM radio and DAB (same region) FM radio DAB power density [% of limit] 1 0,1 0,01 0,001 0,0001 power density [% of limit] 1 0,1 0,01 0,001 0,0001 0, , , , measurement point measurement point 300 measurement points in Nuremberg and Munich region Points statistically distributed; proportional to population density Exposures mostly below % of limit DAB exhibits ~11 db lower exposure compared to FM radio (median) Folie 23

24 Long/Medium/Shortwave radio services Frequency: khz (LW) MHz (MW) MHz (SW) Transmit Power: - several 100 kw per site (up to 2 MW) Transmitter:- several 10 (Germany) Coverage: Distance to Persons: - several 100 km - far field Folie 24

25 Exposure results Study by Wuschek et al., 2003 "Large area measurement of radio waves in Baden-Wurttemberg" (electric field strength)² [% of limit])² 1 0,1 0,01 0,001 0, measurement point 895 points, regular 2 x 2 km grid, outdoor Exposure may reach or exceed GSM/UMTS exposure near to base stations! Folie 25

26 Wireless LAN (IEEE b) Frequency: MHz Transmit power: - max. 100 mw EIRP Transmitter:- several 100,000 Coverage: - several 10 meter Distance to - access points: far field Persons: - mobile: close to body or body contact Remarks: - power control by duty cycle Folie 26

27 Projects supported within DMF Determination of human exposure caused by indoor wireless communication technologies applied in homes and offices (ARC Seibersdorf Research) Determination the real field distribution of high frequency electromagnetic fields near wireless LAN installations (WLAN) in inner cities (ARC Seibersdorf Research) Folie 27 Source: ARC Seibersdorf Research

28 Exposure results (time and space averaged) 0.1 power density [mw/m²] power density [% of limit] distance [m] outdoor scenarios: typ % indoor scenarios: up to 0.1 % close to body operation: typ. 2-3 % of SAR-limit Folie 28 Source: ARC Seibersdorf Research

29 Digital cordless phones: DECT Frequency: MHz Transmit power: - max. 250 mw peak power Transmitter:- several 100,000 Coverage: - several 10 meter Distance to - base station: far field Persons: - mobile: body contact Remarks: - power control by duty cycle Folie 29

30 Projects supported within DMF Determination of human exposure caused by indoor wireless communication technologies applied in homes and offices (ARC Seibersdorf Research) Results: time and space averaged in % of limit 2 DECT devices, 1 and 3 m: BS: %, MS: % SAR 10g : % generic scenarios: % mixed scenarios: % Folie 30 Source: ARC Seibersdorf Research

31 Folie 31 base stations worst case base stations averaged mobile phones (SAR) worst case mobile phones daily life radio service analogue TV DVB-T FM radio 0, limit consumption [% of power limit] ,1 0,01 0,001 0,0001 0, Putting all results together... DAB LMS radio WLAN DECT close to body body contact

32 ... the same with median ,1 0,01 0,001 0,0001 0,00001 body contact close to body indoor 0, base stations worst case base stations averaged mobile phones (SAR) worst case mobile phones daily life analogue TV DVB-T FM radio DAB LMS radio WLAN DECT limit consumption [% of power limit] outdoor radio service median Folie 32 Be carefully with your interpretation!!!

33 Personal exposure meters (Dosimeters) Maschek ESM-140 Antennessa EME Spy Folie 33

34 Folie 34 Problems with cross-talk FM TV3 Tetra TV4&5 GSM Tx GSM Rx GSM Rx GSM Rx DCS Tx DCS Rx DCS Rx DCS RX DECT Frequency bands Antennessa UMTS Tx UMTS Rx UMTS Rx UMTS Rx WIFI

35 Measurement with "extra" exposure GSM/UMTS base station, 350 m Microwave oven, 30 cm Mobile phone, 70 cm Folie 35

36 "Normal" situation Folie 36

37 Dosimeters: Questions to be discussed Limited sensitivity Cross talk between different frequency bands Measurement accuracy - Isotropicity - Influence of the user - Response to modulated signals - Summation of multiple signals in the same band Functional and ergonomic aspects Dosimeters seem to be very helpful for epi-studies, (although their quality need to be investigated in detail) Folie 37

38 Summary and conclusion Relevant exposures are: - mobile phone base stations (GSM+UMTS) and mobile phones - digital and analogue radio and TV broadcast - Wireless LAN and DECT cordless phones Most services exhibit strong time variations (power control) and space variations (fast fading) worst case exposure differs from averaged exposure General comparison of exposures show: - Strongest exposure by sources near to body/body contact - Long/Medium/Shortwave radio service often underestimated Dosimeters seem to be very helpful for epi-studies, (although their quality need to be investigated in detail) Folie 38