This section combines discussion of the environmental setting and analysis of impacts by topic.

...

1. Hammett & Edison, Inc. analyzed existing and proposed radiofrequency levels in the vicinity of Sutro Tower ... This study is included as Appendix A of this EIR and is used as the basis for analysis of radiofrequency levels that would result due to the project.

2. Two experts, Peter Polson, Ph.D. and Louis N. Heynick, M.S., prepared a technical report for this project on whether exposure to radiofrequency radiation (RFR) adversely affects humans and other animals... This report is included as Appendix B of this EIR and is the basis for analysis of health effects that could occur due to RFR exposure from the project.

...

Properties of Electromagnetic Frequencies

Electromagnetic waves come in two forms: ionizing and nonionizing. Nonionizing waves are further categorized as visible light and infrared radiation, radiofrequency radiation (RFR), and extremely low frequency (ELF) electric and magnetic fields. RFR and ELF are further discussed below.

Ionizing Radiation

The shortest wavelengths, or highest frequencies, are ionizing electromagnetic radiation. ... Ionizing radiations, such as ultraviolet light, X-rays, and radioactive emissions, has higher energy levels than nonionizing radiations.

In essence, ionizing radiation absorbed by a molecule yields enough energy to expel an electron from the molecule (ionize it), leaving it positively charged and thus enhancing the interactions of the molecule with its neighbors. Such interactions can alter the functions of biological molecules fundamentally and irreversibly in living organisms. Moreover, the damage caused by ionizing radiation can be cumulative.

No ionizing radiation is present at Sutro Tower or planned as a part of the project.

Nonionizing Radiation

Nonionizing radiation consists of various forms of electric and magnetic fields. ... The energy level of these waves is too low to eject electrons from (or ionize) atoms or molecules.

Radiofrequency Radiation (RFR)

Television broadcasts involve electromagnetic energy... Broadcast antennas are powered by an alternating current. The rate at which the current alternates (or changes from positive to negative), determines the frequency, expressed in hertz (Hz) [cycles per second] or in millions of hertz (megahertz, MHz) or billions of hertz (gigahertz, GHz).

RFR includes ... the frequency range up to 300 gigahertz (GHz or 1 billion cycles per second). These radio waves are a form of nonionizing radiation...such as the radiofrequency waves from Sutro Tower.

The energy content of individual quanta in RFR is so much smaller than ionizing radiation that relatively high rates ... are necessary to produce a physiologically significant amount of heat. RFR heating immediately ends on stopping the exposure.

Exposure levels to RFR are generally referred to as "power densities" ... and are expressed in terms of milliwatts per square centimeter (a milliwatt is one-thousandth of a watt). In general, power density levels from a radiofrequency source decrease according to the inverse square principle; at twice the distance from the source, a point will receive one fourth of the level of radiation exposure.

Sutro Tower currently emits RFR with a frequency range between 54 and 788 MHz during television and radio broadcasts. ...

Extremely Low Frequencies (ELF)

Within the class of nonionizing radiations, a basic difference exists ... between RFR and ... ELF (usually 60 Hz in the U.S.) ... The wavelength corresponding to 60 Hz is more than 3,100 miles...By contrast, the wavelength corresponding to 626 megahertz (MHz) which is the midband frequency of the Sutro DTV broadcast transmitter, is approximately 1.6 ft.

Controversy surrounds reports of the adverse effects on humans from exposure to the electric and magnetic fields present in homes from the power lines supplying electricity to the house ... the interactions with biological bodies differ between radio/television signals and power line frequencies.

No extremely low frequencies are emitted from Sutro Tower for broadcasting television and radio signals.

RFR Regulatory Safety Guidelines

In 1991, the Institute of Electrical and Electronic Engineers (IEEE) issued a set of guidelines for human exposure to RFR developed by the American National Standards Institute (ANSI). ... referred to as ANSI/IEEE Guidelines 1992. ... the resulting standards for the frequency range from 30 to 300 MHz are 0.2 mW/cm² for general public exposure, and 1.0 mW/cm² for workplace exposure.

In December 1996, the FCC adopted revised guidelines (FCC 96 Guidelines) ...and are identical to the 1992 ANSI/IEEE Guidelines. ... In the FCC adopted DTV frequency range (460-806 MHz), the maximum permissible power densities for exposure in uncontrolled environments are in the range 383-672 microwatts per square centimeter (0.38 to 0.67 milliwatts per square centimeter).

...

On December 5, 1996, Hammett & Edison took spot measurements at ten locations using a Holaday Instruments Broadband Exposure Meter ... Of the ten locations measured for RFR in December, 1996, the highest RFR level measured was 0.0229 milliwatts per square centimeter (mW/cm²). ... This calculated value was at 11.5 percent of the FCC 96 Guidelines.

Approximate Power Density	Approximate Distance from Sutro Tower
10 - 15%	at tower to about one city block
5 - 10%	about two city blocks
1 - 5%	about nine city blocks
0.5 - 1%	about 18 city blocks
less than 0.5%	more than 18 city blocks

...