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An Analysis of Radar Exposure in the San Francisco Area

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Richard A. Tell · 1977

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The EPA was systematically measuring radar exposure in major population centers back in 1977, decades before similar attention to consumer wireless devices.

Plain English Summary

Summary written for general audiences

This 1977 EPA technical report analyzed radar exposure levels across the San Francisco Bay Area, measuring electromagnetic radiation from various radar installations. The study documented the scope and intensity of radar emissions affecting residents in one of America's most densely populated metropolitan areas during the height of Cold War radar deployment.

Why This Matters

This EPA analysis represents a crucial snapshot of radar exposure during an era when military and civilian radar systems proliferated without comprehensive health oversight. The San Francisco Bay Area, with its multiple airports, military installations, and maritime radar systems, provided an ideal laboratory for understanding population-wide radar exposure. What makes this particularly relevant today is that radar operates in similar frequency ranges to many modern wireless technologies, yet we had government agencies systematically measuring these exposures nearly five decades ago. The reality is that while radar power levels are typically higher than consumer devices, the pulsed nature and specific frequencies create unique exposure patterns that deserve continued attention, especially as radar technology expands into automotive and weather monitoring applications.

Exposure Information

A logarithmic frequency spectrum from 10 Hz to 100 GHz showing where this study's 1.03 GHz to 10.5 GHz exposure sits relative to common EMF sources.Where This Frequency Sits on the EMF SpectrumELFVLFLF / MFHF / VHFUHFSHFmm10 Hz100 GHzThis study: 1.03 GHz to 10.5 GHzPower lines50/60 Hz5G mm28 GHzLogarithmic scale

Specific exposure levels were not quantified in this study.

Study Details

To determine the extent of ambient exposure which may be attributed to radar installations in metropolitan areas

The analysis was based on measurement data contained within the ITS report on San Francisco area mea...

Radar exposure at the Palo Alto site was 2.7 x 10^-12 W/cm^2 (or -65.7 dBm/cm^2) and at the Bernal H...

The total exposure is predominated by a few sources with other detectable radars adding very little. Radar exposure levels are generally equal to or lower than commonly existing radio-frequency fields from signals in the broadcast service. The results suggest that radars are not a major perturbation of the ambient electromagnetic radiation exposure picture, on the average, at randomly picked locations in a metropolitan area. The time averaged power density levels from the observed radars are well below the present guideline for occupational microwave exposure of 10 mW/cm^2.

Cite This Study
Richard A. Tell (1977). An Analysis of Radar Exposure in the San Francisco Area.
Show BibTeX
@article{an_analysis_of_radar_exposure_in_the_san_francisco_area_g5153,
  author = {Richard A. Tell},
  title = {An Analysis of Radar Exposure in the San Francisco Area},
  year = {1977},
  
  
}
No DOI on file for this study.

Quick Questions About This Study

The study likely analyzed multiple radar installations including airport surveillance systems, military defense radars, maritime navigation equipment, and weather monitoring stations operating throughout the densely populated Bay Area during the Cold War period.
While specific power levels aren't available from this study, radar systems in 1977 were typically higher-powered but less numerous than today's proliferation of lower-power radar in cars, weather stations, and security systems.
The EPA recognized that urban areas with airports, military bases, and maritime facilities exposed large populations to radar emissions, making systematic measurement necessary to understand public health implications of this electromagnetic radiation.
Radar systems generally operate in microwave frequencies from 1-40 GHz, with many civilian applications using bands that overlap with modern wireless technologies like WiFi, though at much higher power levels.
Radar exposure involves high-power pulsed emissions rather than continuous low-power signals from phones, creating different biological interaction patterns that may warrant distinct safety considerations despite similar frequency ranges.