09-18-1996 - Laserfiche WebLink

Home Browse Search

• r JULES COHEN & ASSOCIATES, P.C. • CONSULTING ENGINEERS WASHINGTON. D.C. 20036 • • Engineering Report • Page 2 American Personal Communications Respect to Human Exposure to Radio Frequency Electromagnetic Fields. 3 kHz to 300 GHz) is known as ANSI/IEEE C95.1-1992. In the opening paragraph of the standard, the statement is made: "Recommendations are made to prevent harmful effects in human beings exposed to electromagnetic fields in the frequency range from 3 kHz to 300 GHz. These recommendations are intended to apply to exposures in controlled, as well as uncontrolled, environments." The Federal Communications Commission, the Federal Government licensing agency for non- government users of the radio frequency spectrum, is in the process of adopting that standard as its environmental guide, replacing the 1982 ANSI standard ANSI/IEEE C95.1-1992 was prepared by a committee with about 125 participants. The committee inchldPd biologists, medical doctors, physiologists, medical statisticians and • engineers from academia, government and industry, with industry participants being in the minority. In arriving at its conclusions of maximum permissible exposure to radio frequency fields, the scientific literature was reviewed and a determination made of that exposure level that appeared to be the threshold for the appearance of biological effects which might be harmful if exposure continued over a substantial period of time. An additional safety factor of fifty below the threshold level was applied for "uncontrolled" environments, that applicable to the general public. Because of the low power used, and the direction of maximum radiation toward the horizon to maximize service, the exposure level even directly below the antenna system of the base station is only a small fraction of the permitted level• specified for the uncontrolled environment. Assuming the head of the person is no more than approximately 11 feet below the antenna center, the exposure level would be only in the order of 0.0068 milliwatts per square centimeter (mW/cm2), approximately 200 times below the standard's maximum permissible exposure level of 1.29 mW/cm2. Where the antenna system is mounted on a rooftop, the exposure • levels within the building are below the measuring capability of the instruments normally used for exposure evaluation.