Value chain · CLM-1335
In plain terms
In the 1970s most city dwellers in the US received radio-frequency exposure more than a hundred times below even the strictest heat-based limits the note considered; only people next to big transmitters came close.
The claim as recorded
A 1978 US EPA technical note reports that in EPA's survey of 10 large US cities, for 54 to 890 MHz, the median population exposure was about 0.007 uW/cm2 and 0.7 per cent of the population was exposed above 1 uW/cm2. Inside tall buildings beside broadcast towers it found up to about 0.12 mW/cm2. The note says ground-level exposures were typically more than 100 times below its most conservative thermal limits, and that environmental fields are rarely above 4 nJ/m3.
Evidence behind this: T3, a US EPA technical note reporting EPA's own urban field survey (preliminary results, cited to EPA reports not held).
Scope and limits
Preliminary survey results cited to EPA reports that are not held. Covers broadcast frequencies only, not 2.45 or 5.8 GHz. 1970s levels; mobile and wireless sources since then are not covered. The comparison with a power-beaming rectenna edge (for example 0.1 or 1 mW/cm2 in the 1978 reference system) is not made by the note; any such ratio would be our arithmetic.
What it assumes
The survey's 10 cities and broadcast band (54-890 MHz) represent typical US urban exposure of the 1970s.
Where it comes from
PDF p.40 / printed 30, Figure 10 caption: "The median exposure is 0.007uW/cm2 and 0.7 percent of the population are exposed to levels above 1uW/cm2"; ground-level exposures "typically more than 100 times lower in value" than the most conservative limits. PDF pp.40-41 / printed 30-31: inside tall buildings "about 4 nJ/m3 or .12 mW/cm2". PDF p.43 / printed 33: intensities "rarely above 4 nJ/m3".
Basis: uW/cm2 and pJ/m3, 54-890 MHz broadcast band, population-weighted
Related records
- Answers question
- QST-001 not published in this release
Cite this
energyaperture.com/c/clm-1335
CLM-1335, Energy Aperture, as of 1978-04.
Connected records
Other published records linked to this one. A list, not a judgement.