rf health&safety

June 2001 Copyright 2001 Global Wireless Education Consortium HS-PHS ● 1

Health and Health and SafetySafety

(HS-PHS)(HS-PHS)

June 2001 ● Copyright 2001 Global Wireless Education Consortium HS-PHS ● 2

HS-PHSHS-PHS

© Copyright 2001 Global Wireless Education Consortium

All rights reserved. This module, comprising presentation slides with notes, exercises, projects and Instructor Guide, may not be duplicated in any way without the express written permission of the Global Wireless Education Consortium. The information contained herein is for the personal use of the reader and may not be incorporated in any commercial training materials or for-profit education programs, books, databases, or any kind of software without the written permission of the Global Wireless Education Consortium. Making copies of this module, or any portion, for any purpose other than your own, is a violation of United States copyright laws.

Trademarked names appear throughout this module. All trademarked names have been used with the permission of their owners.


HS-PHSHS-PHS

■ Partial support for this curriculum material was provided by the National Science Foundation's Course, Curriculum, and Laboratory Improvement Program under grant DUE-9972380 and Advanced Technological Education Program under grant DUE 9950039. ‑

■ GWEC EDUCATION PARTNERS: This material is subject to the legal License Agreement signed by your institution. Please refer to this License Agreement for restrictions of use.


Table of ContentsTable of ContentsOverview 5Learning Objectives 6Electromagnetic Radiation 7Site Safety 20Compliance 34Summary 39Contributors 41


OverviewOverview

In this module you will learn about radiated power and how it effects the population. You will learn about personal protective equipment and how to work safely at a site that contains electromagnetic radiation. Standards in the U.S. will be discussed along with OSHA requirements.


Learning ObjectivesLearning Objectives

After completing this module, you will be able to:■ Explain radiated power and its effects on workers and

the general population■ Explain OSHA requirements as they relate to RF

personal health and safety.


Electromagnetic Electromagnetic RadiationRadiation


Electromagnetic Electromagnetic RadiationRadiationElectromagnetic Radiation

Antenna with Vertical

Orientation

Vertical field polarization

shown

Transmitter

E

E

H

H


Electromagnetic Energy Electromagnetic Energy SamplesSamples

Electromagnetic Energy (EME) Examples

FM Radio 30 - 300MHz

AM Radio 550 - 1600KHz

Cellular Phone 824 - 849 MHz 869 - 894 MHz

Paging 35, 43, 152,

158, 454, 931 MHz


Ionizing vs. Non-ionizing Ionizing vs. Non-ionizing FrequenciesFrequenciesIonizing versus Non-ionizing

VisibleLight

ELFfields

RadioWaves

InfraredUltra-Violet

X-Rays

Gamma&

CosmicRays

1050 1012 1014 1015 1017 1020 1024

Frequency,Hertz

Non-ionizing Radiation Ionizing Radiation


EME Mechanism of EME Mechanism of InjuryInjury

EME at frequencies above UV Light have enough energy to tear electrons from their atoms. This can cause permanent biological changes to the molecular structure of cells.


RFR Burn vs. Surface RFR Burn vs. Surface BurnBurn

A RFR Burn starts at the bone and heats outward towards the skin

A surface burn begins at the skin surface and moves inward towards the bone


Whole Body HeatingWhole Body Heating Whole Body Heating

The body acts like an absorptive antenna.

Thin, lossless dipole antenna Fat, water-based body


Whole Body ResonanceWhole Body ResonanceWhole Body Resonance

Subject Ht.(m) Ht.(ft) FR(Isolated) FR(Grounded)

AdultMale

1.75 5’ 9” 86 MHz 43 MHz

NBAPlayer

2.13 6’ 11” 70 MHz 35 MHz

Infant 0.5 1’ 8” 300 MHz 150 MHz

Where λ (m) = 300/F (MHz)


Maximum Potential Maximum Potential Energy CalculationsEnergy Calculations

Examples:■ 0% - 100% of MPE* = No time limit■ 200% of MPE* = 3 minutes, then 3 minutes at 0%■ 300% of MPS* = 2 minutes, then 4 minutes at 0%

*(MPE = Maximum Potential Energy)


Spatial Averaging Spatial Averaging versusversusMetabolic RateMetabolic Rate

■ If measurements were taken at three heights with the following values:❑ 1 foot at 1.0 mW/cm2❑ 3 feet at 2.0 mW.cm2❑ 6 feet at 3.0 mW/cm2

■ The spatial averaging would be 2.0 MW/cm2


Overexposure SymptomsOverexposure Symptoms

■ Symptoms of overexposure to EME include, nausea, headache, an overall feeling of warmth, perspiration, elevated body temperature, and labored breathing. Severe cases can mimic heat stroke.


General Population ExposureGeneral Population Exposure(Uncontrolled)(Uncontrolled)General Population/Uncontrolled Exposure

Exposed persons

have no knowledge

or familiarity with RF,

and are thus unable

to intelligently

manage their

exposure.General Public


Occupational ExposureOccupational Exposure(Controlled)(Controlled)Occupational/Controlled Exposure

Exposed personsare familiar withRF, the site, andcan intelligentlyminimize theirown exposurethrough theirwork practices.

OccupationalExposure


Site SafetySite Safety


Common Radio Common Radio Frequency AntennasFrequency Antennas

■ Examples of common radio frequency antennas include the following:❑ A TV-VHF/UHF antenna has a frequency of 60-600 MHz,

power input of 1,000-100,000 watts, a gain of 10 dB, and an ERP of 10,000-1,000,000 watts.

❑ A FM antenna has a frequency of 80-108 MHz, power input of 100-10,000 watts, a gain of 10 dB, and an ERP of 10,000-100,000 watts.

❑ An AM antenna has a frequency of 550-1700 KHz, power input of 100-10,000 watts, a gain output equal to the input, and an ERP of 500-50 kW.


Multiple Signal SourcesMultiple Signal SourcesMultiple Signal Sources

Antenna 1

H1R1

X2 m

R2 H2

Antenna 2

Multiple Sourceson One Tower

Antenna 1

H1R1

X12 m

R2H2

Antenna 2

X2

Individual Sourceson Multiple Towers

2 m

2 m 2 m

X1X2X3

R1H1

R2 H2R3H3

Single Source,Multiple Points

of Interest


Antenna ParametersAntenna Parameters

Effects of Reflections on RFR Levels

Antenna

direct ray

reflected ray


Effects of Reflections of Effects of Reflections of RFR LevelsRFR Levels

2Ρ ΕΙΡΠ=

2ΡΠΓ

2Ρ

=

p

p

p

PG/4 2 (2) S

ανδ


EPA Model for Broadcast EPA Model for Broadcast and Communication Sitesand Communication Sites

( ) R2

ERP33.4 S =

Where ERP = Effective Radiated Power, in watts

R = Height of antenna, in meters

S = Field strength, in µw/cm2

(For more information, refer to the GWEC module RT-RF Antenna)


Conducting a Site Conducting a Site SurveySurvey

■ The following survey points should be taken into consideration:❑ Extent of hazardous and potentially hazardous areas, both on

and off site.❑ Control techniques that will effectively reduce potential

hazards.❑ Any other situations that might create a hazardous area (e.g.,

chemicals, noise, high voltage, or fall hazard).


Final Site Survey ReportFinal Site Survey Report

■ When conducting a site survey, the surveyor will prepare a final survey report. This report should document the following:❑ Adequacy of administrative controls.❑ Personnel attitudes.❑ Diagrams or pictures of the site.❑ Both roof-tops and tower require drawings with dimensions

showing position of every antenna.❑ Results of calculations performed prior to the survey.❑ Action level radius and height above the ground.❑ All areas where Occupational Controlled and General

Population Uncontrolled levels are exceeded.❑ Conclusions and recommendations.


RFR Personal MonitorsRFR Personal Monitors■ 50 MHz to 2,000 MHz model covers:

❑ Cellular and PCS❑ Paging systems❑ Two-way radio systems❑ SMR systems❑ FM radio broadcast❑ VHF and UHF TV

■ Low Frequency Model covers:❑ AM radio broadcast❑ Low band public safety

■ High frequency model covers:❑ Satellite uplink❑ Microwave point-to-point


Basic Work RulesBasic Work Rules

Certain work rules will help avoid over exposure. These rules are:■ Wear RFR personal monitors at all times when:

❑ Working on a roof-top❑ Working within 30 feet of the base of a tower❑ When climbing on a tower containing antennas.

■ The alarm of an RFR personal monitor has priority over another indication of RFR level, even if there is a sign posted stating the RFR level of the area.

■ Contact the tower owner or management company for special instructions at sites with radio or television broadcast antennas.

■ Wear RFR personal monitors at all times when working within 500 feet of the base of a tower containing any type of radio or television broadcast antenna system.

■ Carry two-way radios when working on a tower within 500 feet of broadcast antennas.


Standards in the U.S.Standards in the U.S.

Standards in the U.S.

Two major standards are used in the U.S.:

IEEE C95.1-1991 (ANSI C95.1-1982)

FCC 1997 Regulations

IEEE

FCC


Radiation Protection Guide Radiation Protection Guide (ANSI C 95.1-1982)(ANSI C 95.1-1982)ANSI C95.1-1982

0.01

MHz

1 3 10 30 100 300 1 3 10 30 100 3003 10 30 100 300

kHz GHz

0.1

1.0

10

100

104

105

106mW/cm2

103

Radiation ProtectionGuide

Time and Whole BodyAveragedf in MHz

900/f2

f/300E&H


OSHA StandardOSHA Standard

■ State OSHAs support the 1997 FCC regulations and are more aggressive than the federal OSHA.❑ Consider total exposure levels (regardless of the source or

owner).❑ Has the authority to levy large fines and suspend operations.


Liability for Service Liability for Service OrganizationsOrganizations

Liability for Service Organizations

All serviceorganizations areliable, even non-electronicbusinesses.– Equipment

installation andmaintenance.

– Tower constructionand maintenance.

– HVAC and elevatorrepair.

– Window washersand exterminators.


ComplianceCompliance


What is Compliance?What is Compliance?What Is Compliance?

Compliance doesNOT requirelicensee to reducepower, nor toeliminate areas inwhich RFR levelsexceed MPE limits(when no human ispresent).


Making a Site CompliantMaking a Site Compliant

■ There are two ways to make a site compliant:❑ Make the site compliant by design❑ Operate under an RF safety program.


Safety ProgramSafety Program

■ If a site is compliant because it operates under a safety program, the safety program in place must:❑ Limit the exposure of individuals not covered by the safety

program to below the General Population MPE levels.❑ Limit exposure to workers covered by the safety program to

levels below the Occupational/Controlled levels.❑ Train covered workers to understand RF safety issues and

know safe work practices.


Determining ComplianceDetermining ComplianceDetermining Compliance

Three Options thatMAY Be Available

1. Use calculationsbased on OET-65tables.

2. Use sophisticatedcomputermodeling.

3. Makemeasurements(surveys).


SummarySummary


SummarySummary

In this module, we have discussed the following topics:■ Ionizing versus non-ionizing electromagnetic radiation■ The biological effects of EME■ Spatial averaging versus metabolic rate■ Overexposure symptoms■ Uncontrolled exposure■ Controlled exposure■ Site safety■ Standards in the U.S.■ OSHA compliance.


Industry ContributorsIndustry Contributors

■ Telcordia Technologies, Inc (http://www.telcordia.com)

The following companies provided materials and resource support for this module:

http://www.telcordia.com/


Individual ContributorsIndividual ContributorsThe following individuals and their organization or institution provided materials, resources, and development input for this module:■ Dr. Cynthia Furse

❑ Utah State University – Department of Electrical and Computer Engineering (http://www.engineering.usu.edu/ece/faculty/furse/index.html)

http://www.engineering.usu.edu/ece/faculty/furse/index.html

rf health&safety

Documents