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Juhasz Juhasz Presentation Transcript

  • RF Personal Exposimetry onEmployees of Elementary Schools,Kindergartens and Day Nurseries as a Proxy for Child Exposures
  • Péter JUHÁSZ József BAKOSGyörgy THURÓCZYNational Research Institute forRadiobiology and Radiohygiene Budapest, Hungary
  • Overview
  • The Objective:To assess the EMF exposure of children
  • Difficulties: Hard to work with childrenParental consent/cooperation requiredIncreased risk to expensive PEM units
  • Workaround: Exposure proxiesMeasure exposure of adults who work in close proximity to children
  • Specifically:Kindergarten/day nursery caretakers School teachers
  • They spend part of their worktime in the same microenvironment(same room) as the children they care for
  • They are expected to receive thesame exposure pattern as the children (at least from base stations and DECT/Wi-Fi sources)
  • Methods
  • RF Personal Exposimetry
  • Exposimeters used:Satimo EME Spy 121Antennessa DSP 090
  • GSM, UMTS:Separation of uplink (emitted by the phone)and downlink (emitted by the base station)
  • Measure interval: 15 or 30 s
  • Volunteer groups:
  • Group Children age n  Kindergarten caretakers 3–6  Day nursery caretakers 50 1–3  School teachers 6–14 30 (n=60 in 2009 and n=20 in 2010)
  • Activity diary
  • Each entry consists of: Description Start of activity Activity type Comment
  • Activity types
  • WorkHomeSleepTravelOther
  • WorkHomeSleepTravelOther
  • Example graph
  • Activity type 10 Work TV among children courtyard microwave oven mobile walk cooking mobile SMS computer microwave washing machine, drier Home 5 Sleep Travel 2Electric field [V/m] Other 1 FM TV VHF 0.5 TETRA TV UHF GSM 900 Phone GSM 900 Base 0.2 GSM 1800 Phone GSM 1800 Base 0.1 DECT UMTS Phone 0.075 UMTS Base 0.05 WLAN 10:00 12:00 14:00 16:00 18:00 20:00 22:00 00:00 02:00 04:00 06:00 08:00 Time [h:m]
  • Manual evaluation of diaries
  • Every diary entry was carefully examined and marked 0–5 as a level of certainty thatthe volunteer was actually near children during that period
  • 5 explicitly stated as such not explicitly stated,4 but can be inferred3 probably2 not likely, but possibly1 unlikely0 unrelated activity
  • Activity type 10 Work TV among children courtyard microwave oven mobile walk cooking mobile SMS computer microwave washing machine, drier Home 5 Sleep Travel 2Electric field [V/m] Other 1 FM TV VHF 0.5 TETRA TV UHF GSM 900 Phone GSM 900 Base 0.2 GSM 1800 Phone GSM 1800 Base 0.1 DECT UMTS Phone 0.075 UMTS Base 0.05 WLAN 10:00 12:00 14:00 16:00 18:00 20:00 22:00 00:00 02:00 04:00 06:00 08:00 Time [h:m]
  • Manual evaluation:tedious, involves a lot of guesswork
  • Simplified evaluation:Every entry marked as Work
  • Further simplified evaluation: Every data point between 8:00 – 16:00
  • Results
  • Number of acceptabledata points as a function of category and grouping
  • Number of acceptable data points 250000 All 2009 2010 Kindergarten School 200000 150000n 100000 50000 10000 0 all 8-16 work 1 2 3 4 5 all 8-16 work 1 2 3 4 5 all 8-16 work 1 2 3 4 5 all 8-16 work 1 2 3 4 5 all 8-16 work 1 2 3 4 5
  • Ratio of pointsabove detection limit
  • Hardware limitation:detection limit of 0.05 V/m
  • Points above det. limit: GSM 900 Base Station 100 All 2009 2010 Kindergarten School 80 60% 40 20 0 8-1 wo 6 1 rk 2 3 4 5 8-1 wo 6 1 rk 2 3 4 5 8-1 wo 6 1 rk 2 3 4 5 8-1 wo 6 1 rk 2 3 4 5 8-1 wo 6 1 rk 2 3 4 5
  • Points above det. limit: GSM 900 Phone 100 All 2009 2010 Kindergarten School 80 60% 40 20 0 8-1 wo 6 1 rk 2 3 4 5 8-1 wo 6 1 rk 2 3 4 5 8-1 wo 6 1 rk 2 3 4 5 8-1 wo 6 1 rk 2 3 4 5 8-1 wo 6 1 rk 2 3 4 5
  • Points above det. limit: GSM 1800 Base Station 100 All 2009 2010 Kindergarten School 80 60% 40 20 0 8-1 wo 6 1 rk 2 3 4 5 8-1 wo 6 1 rk 2 3 4 5 8-1 wo 6 1 rk 2 3 4 5 8-1 wo 6 1 rk 2 3 4 5 8-1 wo 6 1 rk 2 3 4 5
  • 5 4 3 School 2 1 rk wo 6 8-1 5 Kindergarten 4 3 2Points above det. limit: WIFI 1 rk wo 6 8-1 5 4 3 2 1 rk 2010 wo 6 8-1 5 4 3 2009 2 1 rk wo 6 8-1 5 4 3 2 All 1 rk wo 6 100 8-1 80 60 40 20 0 %
  • Descriptive statistics
  • GSM 900 Base Station All 2009 2010 Kindergarten School 2 1E [V/m] 0.5 0.2 0.1 0.05 8-1 wo 6 1 rk 2 3 4 5 8-1 wo 6 1 rk 2 3 4 5 8-1 wo 6 1 rk 2 3 4 5 8-1 wo 6 1 rk 2 3 4 5 8-1 wo 6 1 rk 2 3 4 5 Max Upper quartile Median Lower quartile Mean 90th Percentile 95th Percentile Min
  • GSM 1800 Base Station All 2009 2010 Kindergarten School 2 1E [V/m] 0.5 0.2 0.1 0.05 8-1 wo 6 1 rk 2 3 4 5 8-1 wo 6 1 rk 2 3 4 5 8-1 wo 6 1 rk 2 3 4 5 8-1 wo 6 1 rk 2 3 4 5 8-1 wo 6 1 rk 2 3 4 5 Max Upper quartile Median Lower quartile Mean 90th Percentile 95th Percentile Min
  • WIFI 10 All 2009 2010 Kindergarten School 2E [V/m] 1 0.5 0.2 0.1 0.05 8-1 wo 6 1 rk 2 3 4 5 8-1 wo 6 1 rk 2 3 4 5 8-1 wo 6 1 rk 2 3 4 5 8-1 wo 6 1 rk 2 3 4 5 8-1 wo 6 1 rk 2 3 4 5 Max Upper quartile Median Lower quartile Mean 90th Percentile 95th Percentile Min
  • Other frequencies:Negligible exposure from TV, TETRA, UMTS DECT: negligible, but simplified evaluation overestimates FM: Above-DL but low exposure
  • Comparison by frequencies
  • Category 5 datapoints only as the best quality data for estimating exposure of children
  • Comparison by frequencies: Only points in category 5 All volunteers 10 2E [V/m] 1 0.5 0.2 0.1 0.05 900 1800 UMTS 900 1800 UMTS DECT WIFI FM Base station Phone Max Upper quartile Median Lower quartile Mean 90th Percentile 95th Percentile Min
  • Discussion
  • Quality of exposure diaries varyInformation given by volunteers often incorrect or misleading
  • Data quality is problematic
  • Robust ROS: method to estimate unbiased mean and SD of a left-censored dataset Röösli et al, BEMS 2008, 29:471-478.
  • Attempted, with inconclusive results(Too many points below DL)
  • Only a fraction of the full dataset usable for estimation of exposure of children (n ≈ 4800 out of 265000)
  • To get that usable dataset, diaries have to be manually evaluated
  • Simplified evaluation oftenunder- or overestimates exposure
  • Recommendations
  • The better the diaries,the easier to work with them → Better quality data
  • Proper instruction of volunteers is essential