(6) Reflected radiation.
(7) Ambient temperature.
This limit of 0.01 W/cm2 was established based on thermal effects of microwave
radiation. The current official Army standards (adopted in 1965) permit exposure to
power densities greater than 0.01 W/cm2 but not greater than 0.01 W/cm2 for periods of
time in accordance with the formula:
T = 60
T = Stay time in minutes
w = Power density in mW/cm2
It is not considered feasible to control personnel stay time for periods of less than two
minutes; therefore, it was recommended that the formula not be applied to power
densities greater than 50 mW/cm2. A detailed discussion may be found in TB MED 523,
Control of Hazards to Health from Microwave Radiation and Radiofrequency and
b. To determine whether or not the exposure standards are being complied with,
the power density of the microwave field must be measured. Instrumentation is
available to the field, but in most cases these measurements will be made during the
periodic survey performed by the Laser Microwave Division of the US Army
Environmental Hygiene Agency (USAEHA).
3-8. PERFORMANCE STANDARDS
a. The performance standard for microwave ovens promulgated by Public Law
90-602 says that "power density of the microwave radiation emitted by a microwave
oven shall not exceed one milliwatt per square centimeter at any point five centimeters
or more from the external surface of the oven, measured prior to acquisition by a
purchaser, and thereafter, five milliwatts per square centimeter at any point five
centimeters from the external surface of the oven."
b. The establishment of this standard was based on the increased exposure of
the general public to microwave cooking sources.
c. The absence of data to substantiate or refute a threshold effect for eye
damage from microwave energy necessitates the protection of the public to the limits of
our technical ability.