non-ionizing radiation safety manual

8/3/2019 Non-Ionizing Radiation Safety Manual

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U. C. BerkeleyOffice of Radiation Safety

Non-Ionizing Radiation Safety Manual

11/14/01


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Index

Introduction Page 3

Electromagnetic Spectrum (Chart) Page 3

Non-Ionizing Radiation Safety Policy Page 3

Applicable Regulatory Standards & Guidelines Page 4

Understanding and Evaluating NIR Hazards Page 5

Non-Coherent Light Source Safety (MODULE #1) Page 7

Microwave/RF Radiation Safety (MODULE #2) Page 12

ELF Radiation Safety (MODULE #3) Page 18

Static Magnetic Field Safety (MODULE #4) Page 20

Use of NIR Hazard Signs and Labels Page 25

Appendices Page 26

Appendix A - ORS Contact Information Page 27

Appendix B - NIR Emergency Response Procedure Page 28

Appendix C Microwave Oven Safety Guidelines Page 29

Appendix D Useful NIR Formulas Page 30

Appendix E Bylaws of the Non-Ionizing Radiation Safety Committee Page 32

Appendix F Design of NIR Warning Signs Page 36


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Introduction

The modern world is full of devices which, either directly or indirectly, act assources of non-ionizing radiation (NIR). These sources prod uce NIR in theelectromagnetic spectrum of wavelengths/ frequencies ranging from 100 nm tostatic fields. Many NIR sources are present on the UC Berkeley campu s, either in

research app lications or in ancillary equipment.

In general, NIR tends to be less hazardous to humans than ionizing radiation(ionizing rad iation has a w avelength less than 100 nm or a p hoton energy g reaterthan 12.4 electron Volts). However, depend ing on the wavelength/ frequen cyand the irradiance (or pow er density) value, NIR sources may p resent a hu manhealth hazard. This manu al is intended to provid e guidance in maintaining asafe NIR work environment on th e camp us.

Non-Ionizing Radiation Safety Policy

It is the p olicy of the University of California at Berkeley to prov ide a workp lacesafe from the known hazards of NIR by assuring compliance with federal andstate safety regu lations. Presently, it is not clear if Extrem ely Low Frequ ency(ELF) Radiation poses any hazard to hum an health. However, the ICRP InterimGuid elines on Limits to 50/ 60 Hz Electric and Magnetic Fields are used by th ecamp us as a precaution. The NIR safety program is up graded as newregulations and standards become available.


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This policy app lies to all persons exposed to N IR hazard s on UCB property. TheUC Berkeley Office of Radiation Safety (ORS) has been assigned responsibilityfor implementing the NIR safety policies established by the campus Non-Ionizing Rad iation Safety Com mittee (NIRSC).

NOTE: Ionizing rad iation, lasers, and coherent light sour ces are not covered in

this manu al. For information on the hazards from these sources, see the camp usRadiation Safety Manual, the Laser Safety Manual, and the Laser Safety TrainingSup plement. Please contact ORS to obtain these documents or ad ditionalinformation.

Applicable Regulatory Standards & Guidelines

Non-coherent UV, Visible, Infrared Radiation Title 8- CCR, ACGIH, ANSI Z136.2

Microwave/ Radio Frequency Radiation FCC OET 65, IEEE C95.1, Tit le 8-CCR, ACGIH

Extr em ely Low Fr equency Radiation IRPA/ INIRC - NIR Pr otection Guidelines

Static Magnetic Fields ACGIH

The California Code of Regulations (CCR, Title 8, Section 5085, Subchapter 7,Group 14, Article 104 Nonionizing Radiation) establishes MPE (maximumpermissible exposure) values for frequencies between 3 MHz and 300 GHz. Atpresent, neither the state nor federal government regulates those frequenciesbelow 3 MHz. The Institu te of Electrical and Electronics Engineers (IEEE) C95.1(1991) Stand ard recommends MPE values for frequencies between 3 MHz and 3kHz . This standard is a revision of the American N ational Stand ard Institute(ANSI) C95.1 (1982) and is recognized by AN SI as the stand ard of safety practice.

The Interna tional Radiation Protection Association/ Internat ional Non-IonizingRadiation Committee (IRPA/ INIRC) has published Interim Guidelines on Limitsto 50/ 60 Hz Electric and Magnetic Fields. These guid elines are intend ed to limitthe potential health effects of extremely low frequency (ELF is all frequenciesbelow 3 kHz) rad iation exposu re. IRPA/ INIRC recommend s a continuous MPEof 1000 mG (0.1 mT) for exposure to u ncontrolled environm ents over a lifetime.This standard agrees with the permissible magnetic flux exposure for personswearing cardiac pacemakers recommended by the American Conference ofGovernm ental Ind ustrial Hygienists (ACGIH). NOTE: The ACGIH recomm endsthe electrical field for persons wearing cardiac pacemakers not exceed 1.0 kV/ m.

The Federal Comm un ications Comm ission (FCC) publishes the OET 65 Stand ard

which provides guidance on protection of workers and the public frommicrowave/ RF rad iation emissions from transm ission towers and otherbroad cast facilities.

The American National Standards Institute (ANSI) publishes the Z136.2Standard for the Safe Use of Optical Fiber Communications Systems UtilizingLight Emitting Diodes.


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Compliance with CCR Title 8 is required for all employers in the state ofCaliforn ia. Enforcemen t of these regu lations falls to Cal-OSHA, wh o insp ectscamp us facilities to determ ine comp liance with Title 8. Althou gh the IEEEStandard is not a regulation, it does "...represent a consensus of the broadexpertise on the su bject w ithin the institute..." and is comm only accepted withinthe United States as the safety guid ance for frequencies between 3 MHz and 3

kHz. The IRPA Interim Gu ideline is the best gu idan ce available on ELF safetythat is based on international scientific consensus. The Swedish governm ent hasestablished a performance based emission standard for computer monitormanufacturers (the MPR-II Standard allows a MPE of 2.5 mG), but the safetyneed for this standard has not been accepted by the international scientificcommunity.

Understanding and Evaluating Non-Ionizing Radiation Hazards

The properties and hazards of NIR can best be understood by considering theEM spectrum as three broad categories:

Op tical rad iation (100 nm to 1 mm ) Microwave rad iation (300 GHz to 300 MHz) Radiofrequency and lower frequ ency rad iation (300 MH z to Static Fields)Basic characteristics of optical radiation (ultraviolet/ visible light/ infrared):

Possess small wavelengths, large frequencies, and substantial energy(extreme UV app roaches the photon energy of ionizing rad iation).

Optical theory can be ap plied to an analysis of the rad iation field. Both thermal and photochemical (biological) effects are possible from

exposures (dep end ing on wavelength). Exposures normally occur in the far field where the E (electric) and H

(magnetic) fields are strongly coupled. The inverse square law app lies to any an alysis of the rad iation field. Only power density (S) measurements are normally considered in the hazard

analysis. The radiation interacts readily with sur faces and can easily d eposit energy in

hum an tissues.

Basic characteristics of microw ave rad iation (300 GHz to 300 MH z):

Possess intermediate wavelengths (1 mm to 1 m), frequencies, and moderatephoton energy.

Microwave theory can be ap plied to an analysis of the rad iation field. Both thermal and induced current (biological) effects are possible from

exposures. Exposures may occur in both the near and far fields. In hazard analysis, both E (electrical field) and H (magnetic field)

measurements must be considered in addition to the power density (S)measurements.


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This type of radiation resonates (forms standing waves) in tissue dimensionswith m ultiples of 1/ 2 wavelength (depend ing on the tissue orientation to th ewave plane).

Basic characteristics of Radiofrequ ency an d lower frequency (ELF, static) fields:

Possess large wavelengths (>1 m), small frequencies, and very low energy. Circuit theory can be app lied to an an alysis of the rad iation field. In general there is poor energy d eposition in hum an tissue but therm al and

ind uced curren t (biological) effects are possible. Exposures usually occur in the near field where the E and H fields are not

coupled. The inverse square law m ay not app ly. The E and H measurements must be considered separately for a hazard

analysis (of RF). At ELF and static fields, the magnetic field dominates the hazard analysis. This type of radiation can easily penetrate, but rarely dep osit energy in tissue.


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MOD ULE #1

Non-Coherent Light Source Safety

Many devices (or sources) produce either broadband or discrete wavelengthradiation between 100 nm and 1 mm . Und er certain cond itions, these sources

may p resent a health hazard. Factors affecting the potential hazard includ e: thespecific wavelength(s) produced, the irradiance value, the source dimensions,and whether th e rad iation can access the eye or skin. Sources include (but are notlimited to) the following:

Lamp s (filament , discharge, fluorescent, arc, solid state, etc.) Plasma sources (welding devices, surface deposition, etc.) Heat sources (furnaces, molten glass, open flames, etc.)Whenever practical, sources of non-coherent light not intended for illuminationpu rposes should be shielded to prevent exposure to the eye or skin. For sourcesintended to produce exposure (lamps), any unneeded wavelengths (example:

ultraviolet emitted from mercury vapor lamps) should be removed withapp ropr iate filtration.

Diagram of the Human Eye


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Ultraviolet Radiation

Ultraviolet (UV) rad iation is defined as having a wavelength between 10 nm and400 nm . Specific wavelength ban ds are d efined by the CIE (Comm issionInternational de lEclairage or International Commission on Illumination) asfollows:

Physical Definition Extreme UV (10 nm to 100 nm ) Vacuum UV (10 nm to 200 nm) Far UV (200 nm to 300 nm ) Near UV (300 nm to 400 nm)Photobiologic Definition UV-C (100 nm to 280 nm) UV-B (280 nm to 315 nm) UV-A (315 nm to 400 nm )Ultraviolet Skin Hazards

Ultraviolet (UV) rad iation is a know n carcinogen for hum an skin. In add ition tocancer ind uction, erythema (sunburn ), and skin aging are also known prod uctsof ultraviolet skin exposure. Because the biological effects are depen den t on th etime of exposure, the specific UV wavelength, and the susceptibility of theindividual exposed, it is considered prudent to prevent any unnecessary skinexposure to UV sources. Elimination of unn ecessary skin exposure is reinforcedby the fact that most individuals will receive substantial UV exposure from thesun d uring normal outd oor activities over a hum an lifetime.

UV radiation causes biological effects primarily through photochemical

interactions. The UV wavelengths that p rod uce the greatest biological effects fallin the UV-B, but other wavelengths can also be hazard ous.

Skin p rotection is not d ifficult in theory, as m ost clothing tend s to absorb som e ofthe UV w avelengths. However, in practice, it is often difficult to pr operlymotivate individuals to use appropriate skin protection unless they know theyare receiving an eryth ema (sunbu rn) dose.

Protection of the skin from UV radiation hazard s is best achieved though the useof cloth ing, gloves, and face shields. The use of UV skin blocks (creams orlotions) is considered inadequate for protection against the high irradiance ofman -made UV radiation sources.

Ultraviolet Eye Hazards

Various components of the human eye are susceptible to damage from extendedexposure to direct/ reflected UV exposu re from p hotochem ical effects. The UVwavelength is the determining factor as to which part(s) of the eye may absorbthe radiation and suffer biological effects.


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Absorption of UV wavelengths in the Hum an Eye

wavelength cornea aqueous lens vitreous

100 nm - 280 nm 100% 0% 0% 0%300 nm 92% 6% 2% 0%320 nm 45% 16% 36% 1%340 nm 37% 14% 48% 1%360 nm 34% 12% 52% 2%

The cornea is like the skin in that it can be sunbu rned by exposure to too m uchUV radiation. This is called keratoconjun ctivitis (snow blind ness or weldersflash), a cond ition w here the corneal (epithelial) cells are d amaged or d estroyed.This condition usually does not present until 6 to 12 hours following the UVexposu re. Although very p ainful (often described as having sand in the eyes)this condition is usually temporary (a few days) because the corneal cells will

grow back. In very severe cases, the cornea may become cloud ed an d cornealtransplants may be needed to restore vision. Exposur e to the UV-C and UV-Bpresent th e greatest risk to the cornea.

The lens of the eye is unique in that it is formed early in human developmentand is not regenerated shou ld it become dam aged. For norm al vision, it isessential that the lens remains clear and tr ansp arent. Unfortu nately, UV-Aexposure is suspected as a cause of cataracts (cloud ing of the lens).

To protect the human eye from exposure to UV wavelengths, all that is usuallyneeded is a pair of polycarbonate safety glasses or a polycarbonate face shield.This protective eyewear should be worn whenever there is a potential for

ongoing UV radiation exposu re. Contact the Office of Radiation Safety (ORS) forinformation and ad vice on app ropriate UV protective eyewear.

Visible Light Hazards

All visible light (400 to 780 nm) entering the human eye is focused upon thesensitive cells of the retina w here hu man vision occurs. The retina is the part ofthe eye norm ally considered at risk from visible light h azard s.

Any v ery bright visible light source will cause a h um an av ersion respon se (weeither blink or turn our head away). Although w e may see a retinal afterimage(which can last for several minutes), the aversion response time (about 0.25second s) will normally protect our vision. This aversion response should betrusted and obeyed. NEVER STARE AT ANY BRIGHT LIGHT SOURCE FORAN EXTENDED PERIOD. Overrid ing the aversion response by forcing yourselfto look at a bright light source may resu lt in perman ent injury to the retina. Thistype of injury can occur d uring a single prolonged exposure. Welders and otherpersons w orking with p lasma sources are especially at r isk for this type of injury.


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NOTE: The aversion response cannot be relied upon to protect the eye fromClass 3b or 4 laser exposure (see the Laser Safety Manual for moreinformation).

Visible light sources that are not bright enough to cause retinal burns are notnecessarily safe to view for an extended p eriod. In fact, any su fficiently bright

visible light source viewed for an extended period will eventually causedegradation of both night and color vision. Appropriate protective filters areneeded for any light source that causes viewing discomfort when viewed for anextend ed p eriod of time.

For these reasons, prolonged viewing of bright light sources (plasma arcs, flashlamp s, etc.) shou ld be limited by the use of appr opr iate filters. Traditiona lly,welding goggles or shields of the appropriate shade number will providead equate p rotection for limited viewing of such sour ces. Please contact theOffice of Radiation Safety for ad vice on ap propriate eye protection.

The blue light w avelengths (400 to 500 nm) present a unique h azard to the retina

by causing photochemical effects similar to those found in UV radiationexposu re. Visible light sources strongly weighted tow ards the blue should beevaluated by ORS to determine if special protective eyewear is needed .

Infrared Radiation

Infrared (or heat) radiation is defined as having a wavelength between 780 nmand 1 mm . Specific biological effectiveness band s have been d efined by theCIE (Commission International de lEclairage or International Commission onIllum ination) as follows:

IR-A (near IR) (780 nm to 1400 nm) IR-B (mid IR) (1400 nm to 3000 nm) IR-C (far IR) (3000 nm to 1 m m)Infrared Radiation Hazards

Infrared radiation in the IR-A that enters the human eye will reach (and can befocused up on) the sensitive cells of the retina. For high irradiance sources in theIR-A, the retina is the part of the eye that is at risk. For sources in the IR-B andIR-C, both the skin and th e cornea m ay be at risk from flash bur ns. Inaddition, the heat deposited in the cornea may be conducted to the lens of theeye. This heating of the lens is believed to be the cau se of so called glassblowers cataracts because the heat transfer may cause cloud ing of the lens.

Retinal IR Hazards (780 to 1400 nm) - possible retinal lesions from acute highirradiance exposu res to small dimension sou rces.

Lens IR Hazards (1400 to 1900 nm) - possible cataract induction from chroniclower irrad iance exposures.

Corneal IR Hazard s (1900 nm to 1 mm) - possible flashburn s from acute h ighirradiance exposures.


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Skin IR Hazards (1400 nm to 1 mm) - possible flashburns from acute highirradiance exposures.

The potential hazard is a function of the following:

The exposure time (chronic or acute)

The irrad iance value (a function of both the image size and the source pow er) The environment (cond itions of exposure)Evaluation of IR hazards can be difficult, but reduction of eye exposure isrelatively easy through the use of appropriate eye protection. As with visiblelight sources, the viewing of high irradiance IR sources (plasma arcs, flash lamps,etc.) shou ld be limited by the use of appropr iate filters. Traditionally, weldinggoggles or shields of the appropriate shade number will provide adequateprotection for limited viewing of such sources. Specialized glassblowers gogglesmay be needed to protect against chronic exposu res. Please contact the Office ofRadiation Safety for ad vice on app ropriate eye p rotection.


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MOD ULE #2

Microwave and Radiofrequency Radiation Safety

Microw ave/RF Radiation Sources

The campu s contains man y potential sources of microwav e/ RF rad iationexposure. Some of these sour ces (primar ily antenna s) are designed to emitmicrowave/ RF rad iation into the environm ent. Other typ es of sources (co-axialcables, waveguid es, transm ission generators, heaters, and ovens) are designed toprod uce or safely contain the microwave/ RF rad iation, but may present a hazardshou ld they leak for some reason. A third type of source (primarily powersup plies) may create microwave/ RF rad iation as a byprod uct of their operation.

Factors Affecting Exposure to Microwave/RF Radiation

The hazard s from exposure to microwave/ RF rad iation are related to thefollowing parameters:

Frequency of the source Power d ensity at the point of exposure Accessibility to the rad iation field Does the exposure occur in the near or far field Orientation of the hu man body to the radiation fieldThis combination of factors is used in both evaluating an d mitigating the hazard .

Potential Bioef fects of Exposure to Microwave/RF Radiation

In general, most biological effects of exposu re to microwav e/ RF rad iation are

related to the direct heating of tissues (thermal effects) or the flow of currentthr ou gh tissue (ind uced cu rren t effects). Non-ther m al effects resu lting incarcinogenesis, teratogenesis, etc. have been demonstrated in animals but havenot been proven by epidem iological stud ies on hum ans. The followingbiological effects have been d emonstrated in hu mans:

Cataract formation (from eye exposure). RF (induction) burns. Burns from contact with metal implan ts, spectacles, etc.


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Standards for Microwave/RF Radiation Exposure Protection

A large number of standards have been developed for use in protectingindividuals against overexposure to microwave/ RF radiation. These stand ardsoften ad dress only specific frequency band s or exposu re conditions. In an effortto add ress the broad research p otential for microwave/ RF radiation exposure at

UC Berkeley, the following table of exposure stand ard s was d eveloped. Thetable is a synthesis of several regulatory stand ards and guidelines (as ind icated).

UCB Radio Frequency Exposure Standards(Derived from ACGIH TLV, CCR Title 8, IRPA NIR, FCC OET 65,

and IEEE C95.1)

OCCUPATIONAL EXPOSURE LIMITSAll exposures averaged over 0.1 hour (6 minu tes)

Frequency Band E field (V/ m) H field (A/ m) S (mW/ cm2)


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NON-OCCUPATIONAL EXPOSURE LIMITSAll exposu res averaged over 0.5 hour (30 minutes).

Frequency Band E field (V/ m) H field (A/ m) S (mW/ cm2)


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Identifying and Controlling Microwave/RF Radiation Hazards

The Office of Radiation Safety (ORS) will work with you to identify and assessthe microwave/ RF rad iation hazard s in your work area. Because of thedifficulties of performing actual microwave/ RF rad iation su rveys (near fieldmeasurements, cost of equipment, etc.), it is often necessary to use calculations

and / or comp uter mod els to replace actual measurements in evaluating thehazard.

Antennas and Antenna Arrays

Operation of radio, television, microwave, and other related communicationsystems using electromagnetic radiation, and carrier-current systems requireprior review and app roval by Commu nication an d Netw ork Services (CNS) andthe Office of Rad iation Safety (ORS). Per UC Business and Finance Bulletin IS-5,CNS, in coordination with ORS, will advise you on licensing requirements,operational issues, FCC regulations and the app ropriate exposure mod el to usein your hazar d assessment process. Please provide ORS with a copy of your

hazard assessment for regulatory review. CNS coord inates all FCC applicationswith the Office of President and m aintains all campus-app roved licenses. ORS,in coordination w ith CNS, maintains an inventory of all transmission antennason campus. Please contact ORS before you p lace a new tran smission antenna inor on any camp us bu ilding or location.

Wireless Local Area Networks (WLAN )

Radio frequency based wireless local area networks based on the IEEE 802.11bStandard are becoming available on the campus. Wireless LAN systems (indoorand ou tdoor) are very safe when p roperly installed and used. WLAN systemsoperate on extremely low pow er (less than th at of a cell ph one). It is important

that only app roved equipment be used to build a campus operated WLAN.

Construction or Modification of campus operated WLAN equipment must bereviewed and approved by CNS and ORS in order to prevent potentialhazard ous conditions from existing. The placement of base station antennasshould be high on a w all or on th e ceiling. This not only increases the usefulrange of the system, but also allows for a separa tion d istance of 50 cm, wh ich issufficient of safe operation. In general, persons should avoid d irect contact withantennas attached to computer cards. A separation d istance of 10 cm is sufficientfor safe operat ion.

Other Potential Microw ave/RF Radiation Sources (Leakage Sources)

For waveguides, co-axial cables, generators, sealers, and ovens, probably themost imp ortant aspect of controlling microwave/ RF rad iation hazard s is acareful ph ysical insp ection of the source. Leaking sources will norm ally showmisalignment of doors or plates, missing bolts, or physical damage to planesurfaces. Sour ces, which are susp ected of leaking, shou ld be repaired and thensurveyed w ith app ropriate instrum entation to verify they are n o longer leaking.


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Contact ORS if you n eed assistance with evaluating m icrowave/ RF rad iationleakage hazard s.


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Microwave Ovens

Because of the large number of microwave ovens used and their presence innearly every Department, ORS has special concerns about safety with thesedevices. Specific guidance on microwave oven safety can be found in theApp end ix C in the back of this manu al. It is very un usu al for a comm ercial

microwave oven to leak, but m isuse, damage, and interlock failures have causedovens to leak. Any microwave oven suspected of leaking will be surveyed, uponrequ est, by ORS. Please contact ORS if you w ould like your ovens surveyed.

Power Supplies

Many h igh voltage power su pp lies operate in the m icrowave or rad iofrequencyregions. If damaged , or not prop erly shielded, these sources can leak, produ cingun intended m icrowave/ RF rad iation exposu re. Most of the time, the leakagefrom these sources is minimal and d oes not present a hazard . However, if youhave an indication of microwave/ RF rad iation leakage (RF interference withother equipment or documentation warning of interference), please contact ORS

for a su rvey.


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MOD ULE #3Extremely Low Frequency Radiation Safety

What is ELF Radiation?

Whenever a current passes through a wire, a magnetic field is produced.

Because electric pow er generation in the United States changes p olarity at 60 Hz(cycles per second ), the m agnetic fields generated also alternate at 60 Hz. Sinceabout 1980, these 60 Hz magnetic fields (and their frequency harmonics) havebeen susp ected of causing variou s typ es of negat ive health effects. Thesemagnetic fields are commonly called extremely low frequency (or ELF) fields.

Does ELF Present a Human Health Hazard?

The most accurate an swer is that no one really know s. Although some healtheffects have been statistically related to ELF exposure, these effects are poorlyunderstood and may exist only as statistical or scientific errors. Some researchstudies, which originally indicated ELF health effects, could not be duplicated.

Much of the data supporting effects is from epidemiological studies and theeffects foun d w ere slightly outside the bou nd aries of statistical error. What canbe determined from this information is that any real effect (and thecorrespond ing hazard ) must be relatively small.

Are there Protection Standards for ELF Exposure?

In the absence of conclusive data, the International Radiation ProtectionAssociation/ International N on-Ionizing Radiation Committee (IRPA/ INIRC)have produ ced an interim exposu re guid eline. Although the US Governmen tand the State of California have no regulations on exposure to ELF, UC Berkeleyhas adap ted the IRPA/ INIRC guidelines in order to address employee concerns.

The IRPA/INIRC Interim Guidelines on Limits of Exposure to 50/60 HzElectric and Magnetic Fields

Exposure Type Electric Field Strength in kV/m2 Mag. Flux Density in mT

Occupational

Working day (8 hours) 10 0.5 (5 Gauss)

Short term 30* 5** (50 Gauss)

Extremities (limbs) --- 25 (250 Gauss)

Non-Occupational

Continual - 24 hours/ day*** 5 0.1 (1 Gauss)

A few hours/ day**** 10 1 (10 Gauss)

* The duration of exposure to fields between 10 and 30 kV/ m 2 may be calculated from the

formula t < 80 E, where t is the du ration in hou rs per work d ay and E is the electric field str ength

in kV/ m 2 .

** Maximu m exposure du ration is 2 hours p er workd ay.


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*** This restriction applies to open spaces in which members of the general public might

reasonably be expected to spend a substantial part of the day, su ch as recreational areas, meeting

ground s, and the like.

**** These values can be exceeded for a few m inutes each d ay prov ided p recautions are taken to

prevent ind irect coup ling effects.

What is a normal ELF Field at UC Berkeley?

Since even the wiring for electric lights will generate ELF magnetic fields, thesefields are present in virtually every room of every building on camp us. The ELFfield intensity is a fun ction of the amp erage passing through th e wiring. Ingeneral, transformers and large motors will produce the most intense fields.Mechan ical spaces and m achine shops norm ally have th e most intense fields andthese may (rarely) exceed the non-occup ational exposu re limit. Laboratories andoffices usually do not have intense fields and a reasonable average value forthese areas has been measured at about 3 to 5 mG (milliGauss). So normally, theELF fields UC Berkeley employees are exposed to are less than 1% of the non-occupational exposure limit.

Who Should I Call if I Have ELF Concerns?

The Office of Radiation Safety is available to address questions on ELF exposure.A number of training documents are available to explain what is (and is not)know n abou t ELF exposure and health effects. Please contact ORS if you w ouldlike copies of these documents.

ORS is also available, upon request, to perform ELF surveys of specificequipm ent or w ork areas. Survey reports w ill characterize the ELF field intensityin the areas su rveyed, bu t cannot specifically ad dress the hazard s of fields foun dto be in excess of the IRPA/ INIRP Guidelines.

ORS will normally recommend that exposu re to fields in excess of the guidelinesbe mitigated so as to prevent exposure above the IRPA/ INIRP Guid elines toemp loyees or stud ents. Since there is no legal requ irement to contr ol ELFexposure, the implementation of such recommendations is at the discretion of theDepartment.


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MOD ULE #4

Static Magnetic Field Safety

Many sources (devices) on the UC Berkeley campus produce static magneticfields. Static magnetic fields result from either fixed magn ets or the magnetic

flux resulting from the flow of direct cur rent (DC). Sources prod ucing thesefields include (but are not limited to) the following:

Nuclear Magnetic Resonance (NMR) imaging and spectroscopy devices Electron Paramagnetic Resonance (EPR, ESR, EMR) devices Helmholtz Coils, Solenoids, DC Motors, etc.Factors Affecting Static Magnetic Field Hazards

Under certain conditions, sources of static magnetic fields can present healthhazard s. Factors affecting the potential hazard s include:

Magnetic flux intensity associated with the source Design of the magnetic field source Accessibility of the magnetic field Equipment/ hazard ous materials associated with the magnetic field sourceSources of large static magnetic fields may require appropriate controls tomitigate potent ial hazards. For sources intended to produ ce hu man exposure tothe magnetic field (such as MRI devices), it is critical that safety precautionscover not only the user of the device, but also the research subject.

Bioeffects of Exposure to Static Magnetic Fields

There are no known adverse bioeffects for flux densities within the ACGIH(American Conference of Governmental Industrial Hygienists) exposure limits.Implanted m edical devices present a p otential hazard to individuals exposed tofields above the ACGIH limits (see following section on kinetic energy hazard s).

Kinetic Energy Hazards

Due to the large fields associated with NMR magnets, ferrous objects can beaccelerated toward the magnet w ith sufficient energy to seriously injure p ersonsand / or dam age the magnet. As a precaution, even small metal objects (screws,tools, razor blades, paper clips, etc.) should be kept at least 1.5 meters from the

magnet (or anywhere the field exceed 30 G). Large ferrou s objects (equipm entracks, tool dollies, compressed gas cylinders, etc.) should be moved with carewhenever the field app roaches 300 G. There are man y recorded instances inwhich large objects have been drawn towards and even into the bore of themagnet.


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Standards for Exposure to Static Magnetic Fields

The ACGIH and International Council on Non-Ionizing Radiation Protection

(ICNIRP) have set guidelines for continuous exposure to static electromagneticfields as ind icated in th e table below:

Note: 1 Gau ss (G) = 0.1 millitesla (mT)

5 G Highest allowed field for implanted cardiac pacemakers.10G Watches, cred it card s, magnetic tape, comp uter d isks damaged .30G Small ferrous objects present a kinetic energy hazard.600 G Allowed TWA for rou tine exposure (whole body).6000 G Allowed TWA for routine exposure (extremities).20,000 G (2T) Whole body ceiling limit (no exposure allowed above th is limit).50,000 G (5T) Extrem ity ceiling limit (no exposu re allowed above th is limit).

NOTE: TWA exposu re time is normally only a concern for extremely high fieldexposures to the whole body.

Magnetic Field Measurements

NMR magnets comm only pr oduce core fields from 0.2 T to 20 T. These fieldsdecrease in intensity as the distan ce from the core increases. A field strengthmap of the area surround ing the magnet should be developed and posted for useby staff. If the magnetic fields in your laboratory have not yet been evalua ted,please call the Office of Radiation Safety (ORS) at 3-8414 to schedule a survey.

Posting of Magnetic Field Hazards

All access points to rooms containing magnets fields in excess of 5 G shall bema rked w ith magn etic field hazar d signs (available from ORS). The 5 Gthreshold line shall be clearly identified with floor tape or equivalent markings.The location of the 5 G line w ill vary w ith the op erating frequency and resultingmagnetic fields. As an example, one vend or indicates the following values fortheir NMR spectroscopy equipm ent:

Op erating frequen cy of 200 MHz - 5 G thresh old line @ 1.3 metersOp erating frequen cy of 500 MHz - 5 G thresh old line @ 3.5 metersOp erating frequen cy of 800 MHz - 5 G thresh old line @ 6.0 meters

Access Restrictions

Persons with cardiac pacemakers or other implanted medical devices shall berestricted to areas ou tside the 5 G threshold line. Security (locked door s) andproper door m arkings shall be maintained to prevent u nauth orized access to themagnet area.


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Cryogenic Gas Issues

Types and Expansion Ratios - The cryogenic (liquefied) gases used with NMRmagnets are Liquid Nitrogen (-320 deg. F) and Liquid Helium (-452 deg. F). Ifthese liquids are raised to room temperature, the resulting gases expand tohundreds of times their liquid volumes, possibly displacing the air in the room

(LN = 694/ 1, LH = 700/ 1).

Quench - Quench is the (normally unexpected) loss of superconductivity in aNMR magnet resulting in rapid heating through increased resistance to the highcurrent. This can violently damage the magnet and cause rapid ven ting of largevolumes of He/ N gas into the room, quickly resulting in an oxygen d eficientatmosp here. To avoid a quench situation, use cryogen level sensors and alwaysrefill or de-energize the magnet if low cryogen levels are indicated on thesensors. NOTE: Qu ench cond itions can result from ferrous objects being d raw ninto the magnet bore.

Personal Protective Equipment (PPE) - When handling cryogens, use insulated

gloves and face shields or other splash eye/ face p rotection, closed-toed shoes,and lab coats.

Dewars - The containers used for transporting cryogens should be made ofmetal. Glass dewars can easily imp lode, causing seriously injury. All dewarsshould have app ropriate pressure vents. Unvented containers can rup ture as theliquid w arms and expand s. All transfers of cryogens should be continuou slyattended to prevent spills or frozen valves.

Room Ventilation - Generally speaking, five complete room air changes perhour is considered adequate for managing small spills or releases of cryogens. Inthe event of a major release, the staff shou ld imm ediately leave the room and the

room d oors should be left open. If the risk of a catastrophic release exists,auxiliary ventilation should be considered to prevent the formation of an oxygendeficient atm osphere.

Bioeffects o f Cryogen Exposure - Direct contact with the skin or eye tissues cancause severe dam age throu gh frostbite (tissue d amage from freezing). If thefrostbite is severe, the dam aged tissues may need to be amp utated . Inhalation ofconcentrated cryogen gases may cause loss of consciousness and (eventually)death th rough oxygen deprivation (asph yxiation).

Electrical Safety Issues

Power Supplies - Although the pow er supp lies used for NMR magnets operateat relatively low voltages (about 10 V), the current used is very large (about100A). High amp erage is extremely dangerou s if allowed to come into contactwith tissues.


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Cables, Wires, and Connectors - All cables, wires, and connectors should beprop erly insulated to prevent contact with the op erating current. These shouldbe inspected on a regu lar basis to assure the integrity of the insulation. In orderto preven t arcing; never break connections withou t first turning off the power tothe circuit being hand led.

LOTO (Lock Out, Tag Out) - Cal-OSHA requires all workers to follow LOTOprocedures when working on equipment which is activated by a hazardousenergy source. Contact the campus EH&S Unit for information on LOTOrequirements.

Qualification of Electrical Workers - Cal-OSHA requires that persons w ho workon electrical equip ment be pr operly qua lified. Contact the campus EH&S Unitfor information on qualification requ irements.

Home Built Equipment - Must be designed and maintained so as to meet safetystandard s. Enclosures with proper ground ing and safety markings are requiredfor all home bu ilt electronics.

Bioeffects of Electrical Exposure - Current moving across a break in an electricalcircuit may cause a high temperatu re arc to occur. Depend ing on the curr ent,th is arc can exceed 10,000 deg. F, causin g severe bu rns. Blast effects resultin gfrom the vaporization of copper or other metals in the arc can throw people andequip men t across rooms, causing severe trau ma inju ries. Even if an arc is notstruck, current flowing through tissues can result in burns, blow out injuries,and possible cardiac failure (depend ing on the line frequency). Every effort mustbe made to follow good electrical safety practices and avoid direct contact withlive current.

Radiofrequency Radiation (RF) Issues

RF Sources - The RF source being used for the NMR should be commerciallyprod uced or equivalent qua lity if assembled in the laboratory. Units that are labbuilt or modified should be checked to assure they are safe and do not leakradiation.

Waveguides and Coils - Shou ld be carefully checked to assure th ere are no gapsor loose bolts that will allow leakage of the rad iation. Care should be taken toavoid d irect contact with coils to avoid RF burns.

RF Measurements - If the RF fields in your laboratory need evaluation, pleasecall the Office of Radiation Safety (ORS) at 3-8414 to obtain a su rvey.

Bioeffects - Exposure to high level RF fields can cause heating and damage oftissues. Skin burns can occur from d irect contact with RF coils.


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Other Hazard Issues

Tripping Hazards - Cables and wires lying about on the floor can presenttripp ing hazard s. Please make every effort to keep cables in trays or covered bybridges.

Fire Protection - A Class C fire extinguisher should be kept nearby to deal withelectrical fires. The power m ust be shut d own before attemp ting to fight anelectrical fire. All staff shou ld be trained in fire pr otection an d evacu ationprocedures.

Earthquake Concerns - Magnet assemblies may weigh several tons and must berestrained so they will not move about or tip over du ring an earthquake. Theirplacement shou ld take into accoun t structur al steel sup port mem bers. Powersup plies should also be secured to prevent movem ent in an earthquake.

Ergonomic Concerns - The prolonged use or improper ergonomic setup of VDTstations may cause eye or neck strain pr oblems. Back injuries may result from

the u se of imp roper lifting procedu res or lifting heavy objects without assistance


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Use of NIR Hazard Signs and Warning Labels

Depending on th e accessibility and level of NIR hazards, it may be necessary tomark rooms or other areas with appropriate warning signs (static magneticfields, UV light, etc.). Please consu lt with ORS on the need for such signs prior toplacing them. Please refer to Appendix E for the appropriate design of warning

signs. ORS prov ides these and oth er custom N IR signs up on request. Pleasecontact ORS for assistance with warn ing signs.

Warning labels should be placed on equipment to indicate the presence ofspecific NIR hazard s (UV light, RF fields, etc.). Again , please consu lt with ORSon the need for such labels prior to placing them . ORS provid es these labelsup on request. Please contact ORS for assistance with warning labels.


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APPENDICES


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APPENDIX A

ORS Contact Information

The UC Berkeley Office of Radiation Safety (ORS) is always available forconsultation and / or assessment of NIR hazard s. If you have questions or need

assistance with N IR issues please contact ORS at the nu mbers below:

ORS Office number (8 to 5 M to F) 3-8414

ORS Emergency Response (after hours) 911 (ask for UC Berkeley ORS)

Laser Safety Officer 3-9243 ([email protected])

ORS Web Site http:/ / radsafe.berkeley.edu


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APPENDIX B

NIR Emergency Response Procedure

In the event of an accident involving an NIR source, immediately do the following:

1) Using caution first shut down the source of the NIR radiation and then lockout/tag out the power supply.

2) Provide for the safety of personnel (first aid, evacuation, etc.) as needed.

NOTE: If an eye injury is suspected, have the injured person keep their headupright and still to restrict any bleeding in the eye. A physician should evaluateeye injuries as soon as possible.

3) Obtain medical assistance for anyone who may be injured.

University Health Service (Urgent Medical Care) 2-3188UC Optometry Clinic (Normal Hours) 2-2020

UC Optometry Clinic (24 Hour Emergency) 2-0992Ambulance (Emergency) 9-911

4) If there is a fire, leave the area, pull the fire alarm, and contact the fire departmentby calling 9-911. Do not fight the fire unless it is very small and you have beentrained in fire fighting techniques.

5) Inform the Office of Radiation Safety (ORS) as soon as possible.

(During normal working hours, call these numbers)

ORS Office number 3-8414Laser Safety Officer 3-9243

Radiation Safety Officer 3-7976

After normal working hours, call 911 or 2-6760 to contact the UC PoliceDepartment (they have an ORS emergency call list).

6) Inform the Principal Investigator (PI) as soon as possible. If there is an injury, thePI must submit a report of injury to Risk Management.

7) After an accident, do not resume use of the NIR source until released to do so bythe Non-Ionizing Radiation Safety Committee (ORS will coordinate accidentinvestigations).


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APPENDIX C

Microwave Oven Safety Guidel ines

Do not operate the oven if it is dam aged or does not operate properly. It isimperative that the oven door seals properly and that there is no dam age to

the d oor seal, hinges, latches, or oven su rfaces.

Ovens used for food preparation must be cleaned on a regular basis topreven t biological contam ination, fire potential, and door seal damage.

Ovens used for laboratory applications cannot be used for food preparation.Conversely, food preparation ovens should never be used for otherapplications.

Do not use aluminum foil or any metal containers, metal utensils, metalobjects, or objects with metal or foil trim in th e oven. Such items can cause

arcing, dam aging the oven and creating a fire or burn hazard . A classic item,which is often overlooked, is the metal hand le on the pap er Chinese food box.

Do not heat objects that are sealed as they may explode, damaging the ovenand blowing off the door.

Never heat any flammable or combu stible liquid in the oven. A fire and / orexplosion may result.

Be careful when rem oving containers from the m icrowave. Containers ortheir contents may be very hot, resulting in bu rns or spills of hot materials.

If a fire should start inside the oven, leave the door closed, disconnect thepow er cord and call the fire departm ent at 911. Never make adjustments to or tamper w ith any comp onent of the oven. Do

not try to perform repairs on your own . The oven operates on high voltageand amp erage that can be lethal if improperly hand led.

Generally speaking, commercially available microwave ovens are very safeand reliable, regard less of the man ufacturer. All ovens prod uced for sale inthe United States must meet a strict FDA/ CDRH p rodu ct performancerequirement that limits their microwave leakage during service to


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APPENDIX D

USEFUL NIR FORMULAS

frequency/wavelength relationship

c = or

= c /

or

= c /

w here: c = 3 x 10

8m/s

= wavelength (m)

= frequency (Hz)

energy/frequency relationship

Q = h where: h = 6.626 x 10-34 (Js)

or h = 4.136 x 10-15 (eVs)Q = energy in (J or eV) = frequency (Hz)

pow er density/electric & magnetic fie ld relationship

S = E H where: S = power density (W/m2)

S (mW/cm2) = 37.7 x H2 = E2 / 3,770 E = electric field (V/m)

E / H = 377 (ohm) H = magnetic field (A/m)

magnetic flux density/permeability & magnetic field relationship

B = H where: B = magnetic flux density (T)

1 T = 104 G (Gauss) = 1.26 x 10-6 (H/m)

1 A/m = 1.26 T = 12.6 mG H = magnetic field (A/m)

magnetic field/current & distance relationship

H = I / 2 r where H = magnetic fi eld (A/m)

= 1.26 x 10-6 (H/m)

I = current (A)r = radius (m)

antenna gain

G / A = 4/2

or G = A (4/2

) w here: G = gain (numerical)A = area of antenna (m2) = 3.1416

= wavelength (m)


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far field power density

S = G P / 4 r2 = A P / 2 r2 where: P = power output (W)

S = pow er density (W/ m2)r = distance from antenna (m) = wavelength (m)

A = area of antenna (m2)

defining far field

FF = D 2 / 4 (for a circular antenna) = G / 4 n (for other antenna shapes)

w here: D = P G / 4

n = eff. factor (assume 0.8)

assume the near field power density to be constant at 4 P for safety purposes .

near field pow er density

S = 16 P / D2 = 4 P / A where: P = average power (W)

D = antenna distance (m)

A = area of antenna (m2)

S = pow er density (W/ m2)

limit of the near field

NF = D2 / 8 = A / 2 where: NF = l imit (m)

D = antenna distance (m)

A = area of antenna (m2) = wavelength (m)


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Appendix E

Bylaws of the Non-Ionizing Radiation Safety Committee(NIRSC)

(06/ 04/ 01)

1. Authority and Responsibil ity

The Non-Ionizing Radiation Safety Committee (the Committee) is appointed bythe Chan cellor or his design ee (the Vice-cha ncellor for Research). ThisCommittee was formerly known as the Laser Safety Committee. The Committeereports to the Vice-chan cellor for Research.

The Committee is delegated the authority and responsibility for setting campuspolicy in laser and other non-ionizing radiation safety, within the scope of thecampus Laser Safety Program and the campus Non-Ionizing Radiation (NIR)Safety Program; for reviewing laser and other NIR source uses, and, whereappropriate, authorizing such uses; for reviewing the operations and procedures

of the Office of Rad iation Safety (ORS) with respect to laser and other NIR safetyand offering comments to the Laser Safety Officer (LSO) and the ORS Director(the campus RSO) regarding ORS laser and other NIR safety operations andprocedures.

NOTE: Non-ionizing radiation shall be defined as all electromagnetic radiationwith either a wavelength > 100 nm or a p hoton energy < 12.4 eV.

The Committee has the first responsibility to act in the best interests of safety.The Committee has the au thority to terminate a laser or other N IR source use,should termination be warran ted. Comm ittee decisions to revoke or suspend th euse of a laser or other NIR source may be appealed to the Vice-chancellor for

Research. The Vice-chancellor for Research w ill meet w ith the p etitioner, ORSstaff, and mem bers of, or the full, Non-Ionizing Radiation Safety Committee, asnecessary, to make a determ ination as to revocation or suspension. Decisions tomodify actions of the Non-Ionizing Radiation Safety Committee will betransmitted to the Committee in wr iting and included in their files.

2. Composition

The Committee consists of not more than 10 or less than 5 members exclusive ofex-officio mem bers. Mem bership of the Committee shall meet app rop riatefederal and state guidelines (if any) for composition of the Committee.

Experience: Members are app ointed on the basis of know ledge of the pr inciplesand practices of the control of hazards resulting from or associated with the useof lasers and other NIR sources. The membership is to reflect the diversity ofscientific disciplines using lasers and other NIR sources on campus.

Ex-officio members: The campus Laser Safety Officer (LSO), and the campusRadiation Safety Officer serve as ex-officio members. Oth ers ex-officio mem bersmay be app ointed by the Committee.


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3. Length of Service

Members will normally serve for a three-year term but may be re-appointed foradditional terms.

4. Appointment Process

Appointment of the Comm ittee: On behalf of the Chan cellor, the Vice-chan cellorfor Research shall receive nominations from the current Chair and may solicitnominations from Senate Com mittees and other academ ic administrative officersas appropriate.

Chair of the Comm ittee: The Chair is selected from am ong continuing m embersof the Committee, and will normally have at least two years prior service as amem ber. Re-appointm ent of the Chair beyond a one-year term w ill be at therecomm end ation of the Vice-chan cellor for Research.

5. Functions

(a) General

The Committee is responsible for setting campus policy in laser and NIRsafety, within the scope of the campus Laser Safety Program and NIRSafety Program; for reviewing uses of laser and other NIR sources,authorizing laser and other NIR source use where appropriate; andreviewing and approving procedures of the ORS with respect to laser andother NIR safety.

(b) Use of NIR Sources.

The Committee authorizes the use of laser or other NIR sources whereappropriate. Any authorizations granted are to be supported bydocum entation includ ing the following:

(l) Adequate experience and training of the Auth orized User;

(2) Sufficient and appropr iate equ ipm ent and facilities;

(3) Ad equate plans and procedures for the use of laser or other NIRsources; and

(4) Establishm ent of procedu res to redu ce the potential for laser orother N IR related incidents and accidents.

(c) Review of Author ized Uses

The Committee is to verify that each authorized laser or other NIR use isperiodically reviewed by the ORS.


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The Committee will review safety issues regard ing laser or other N IR usesreferred by the LSO or RSO, and will determine whether to modify,restrict, or terminate the use of a laser or other NIR source.

(d) Review of the ORS Laser an d NIR Safety Activities

The ORS staff is responsible for the day-to-day implementation of thecampus Laser Safety Program and NIR Safety Program and for assuringthat laser and other NIR sources are used in conformity with policies setby the Comm ittee. ORS brings to the attention of the Comm ittee mattersaffecting campu s laser an d other N IR safety, changes need ed in campu slaser or NIR safety policy, and changes in stand ard s or regu lations relatedto laser or other NIR source use and safety. ORS provides such repor ts,sum mar ies, and statistics as the Committee may requ ire. The Comm itteereviews the operations and procedures of the ORS with respect to laserand other NIR safety and offers comments to the LSO and the ORSDirector regard ing laser and other NIR safety operations and procedu res.

(e) Meetings

(l) The Comm ittee meets once each calendar quar ter for the pu rpose ofreviewing campus laser and other NIR safety issues, operationsand procedures of ORS with respect to laser and other NIR safety,and to consider oth er materials needing its attention.

(2) At the discretion of the Comm ittee Chair, or the LSO, specialmeetings may be called to review and approve laser or other NIRsource use, review and act on laser or other NIR incidents, reviewand make changes in campu s laser or NIR safety policy, and / orconsider matters referred by the LSO, the Director of the Office of

Radiation Safety, or members of the Committee.

(3) A quorum , consisting of a simple majority of the mem bership, shallbe present at all meetings and will includ e the LSO and the Directorof ORS, or designated alternates.

(4) The LSO, the Director of ORS, or a designated alternate keepsminu tes of the m eetings. Copies of the minutes are sent to m embersof the Committee. ORS mainta ins a file of the Comm ittee meetingminu tes and associated Committee files.

(f) Annual Report

The LSO prepares an annual report detailing the activities of theCommittee. This report shall be reviewed and ap proved by theCommittee Chair prior to being submitted to the Vice-chancellor forResearch.


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6. Review of Laser and N IR Source Uses

Laser and other N IR source uses are reviewed by the LSO. The ORS reviewseach laser use at least ann ually and N IR uses as app ropr iate. Problemsdiscovered during these reviews that cannot be resolved or are of concern arereferred to the Chair of the Committee. The Chair of the Committee may refer

problems or issues to the entire Committee for review an d comm ent.


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Appendix F

Design of NIR Warning Signs


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non-ionizing radiation safety manual

Documents