Nonionizing Radiation (NIR) Overview Stephen Hemperly, MS, CIH, CSP, CLSO Local Section Regional Representative AIHA Pacific Region Rio Grande AIHA Fall

Nonionizing Radiation (NIR)Overview

Stephen Hemperly, MS, CIH, CSP, CLSOLocal Section Regional RepresentativeAIHA Pacific Region

Rio Grande AIHA Fall Technical MeetingDecember 4, 2014

December 2014

Agenda• Introduction to nonionizing radiation (NIR)

– Optical Radiation (includes Laser Radiation)• Ultraviolet (UV) Radiation, • Visible Radiation, • Infrared (IR) Radiation,

– Radio-Frequency (RF) Radiation– Extremely Low Frequency Fields (ELF)– Static Fields

• Characteristics & Sources• Exposure Guidelines• Biological Effects• Relevant Standards• Ancillary Hazards• Exposure Controls • Additional Information Resources• Concluding Remarks

2Nonionizing Radiation Overview

December 2014

Electromagnetic Spectrum

NIR portion of spectrum covers 15 orders of magnitude in frequency units.


December 2014

Electromagnetic Radiation (EMR): Definition and Physics

• The propagation of radiant energy through space and matter by time-varying (vibrating) electric (E) and magnetic (H) fields.

• This radiation may be characterized as particles or waves (per wave-particle duality).

• Per quantum theory, EMR = discrete particles (photons)

• When characterized as a wave, EMR is described in terms of wavelengths


December 2014

Electromagnetic Wave

The electric field vector (solid line) is vibrating up and down in the plane of the paper, while the magnetic field vector (dashed line) is vibrating in and out of the plane of the paper. The direction the radiation is moving is defined by a third vector — the propagation vector, k. Electromagnetic fields are transverse to the direction of propagation and contained within the envelope formed by the axis of propagation and the sinusoidal waves.


December 2014

Electromagnetic Radiation• May be described by three quantities:

– Photon energy (E in joules)– Wavelength (λ) – distance between 2 points in the same

phase of consecutive wave cycles; also, one complete cycle of a wave -- units of length: nanometers (nm, 10-9) or micrometer (μm, 10-6)

– Frequency (ƒ) – number of complete wave cycles that occur in one second (units of frequency: 1 hertz (Hz) = 1 cycle per second; multipliers = GHz (109 Hz), MHz (106 Hz), kHz (103 Hz)

• E = hƒ = hc/λ Where h is Planck’s constant (6.626 x 10-34 J - seconds), c is speed of light 3.00 x 108 m/s, is λ wavelength (m), and ƒ is frequency in Hz

• Photons with relatively long wavelengths (and low frequency) have relatively low energy

• Lower photon energy = lower potential hazard6Nonionizing Radiation Overview

December 2014

Ionizing vs. Nonionizing Radiation

Nonionizing radiation is electromagnetic radiation with insufficient photon energy to ionize matter.

Generally, the division between nonionizing and ionizing radiation is photon energy of 12.4 electron volts (eV) [Photon of this energy has a wavelength of 100 nm.] Photons with energy less than this value are nonionizing radiation.

Unlike ionizing radiation, non-ionizing radiation cannot dislodge electrons from atoms/molecules with which it interacts – cannot ionize biological matter.


December 2014

Electromagnetic Fields

Field – any physical quantity that has different values at different positions in space.

Electric fields are derived from electric charges

Magnetic fields are derived from moving electric charges


Electric (E) Fields• Created by any charged object whether still or moving;

lines of force or flux

• Described by the magnitude or intensity (E) of voltage difference or gradient between two points in the field

• E is proportional to the voltage difference and inversely proportional to the distance between the two points.

• Electric field strength is calculated by dividing the voltage between two points by the distance between them: volts per meter (V/m).

• Easily shielded – many common materials influence these fields

December 2014 9Nonionizing Radiation Overview

Electric Fields

Electric field lines – A) from positive point charge; B) between linearly distributed positive and negative charges


Magnetic (B) Fields• Created by moving electric charges – currents

• Defined by magnitude and direction of force exerted on a moving charge (current)

• Apply force to moving ions in a biological system

• Difficult to shield effectively – many common materials exhibit low permeability

• Permeability is a measure of how magnetizable a material is (iron-containing materials exhibit high permeability)


Magnetic Fields

Current flow (I) produces magnetic field with magnetic flux density (B).


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Source: National Institute of Environmental Health Sciences (NIEHS): EMF Questions and Answers: Electric and Magnetic Fields Associated with Electric Power. NIEHS, 2002. http://www.niehs.nih.gov/health/docs/emf-02.pdfDecember 2014 Nonionizing Radiation Overview

14

Source: National Institute of Environmental Health Sciences (NIEHS): EMF Questions and Answers: Electric and Magnetic Fields Associated with Electric Power. NIEHS, 2002. http://www.niehs.nih.gov/health/docs/emf-02.pdf

December 2014 Nonionizing Radiation Overview

December 2014

Fundamental Characteristics of NIRRegion Wavelength FrequencyUltraviolet 100–400 nm —— UVC 100–280 nm —— UVB 280–320 nm —— UVA 320–400 nm ——Visible 400–770 nm ——Infrared 770 nm–1 mm —— IR-A 770 1 – 400 nm —— IR-B 1.4 – 3.0 µm —— IR-C 3.0 µm – 1mm ——Radio-frequency (RF) —— 300 GHz–3 kHzExtremely low frequency —— 3 kHz–3 HzStatic fields —— ——

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Note: Lower frequency RF (less than 300 MHz) and ELF energies are referred to as fields rather than radiation.

Nonionizing Radiation Overview

December 2014

Spectral Bands for Optical RadiationRegion Band Wavelength

Ultraviolet UV-C 100-280 nm UV-B 280–315 nm

UV-A 315–400 nm

Visible 400–770 nm

Infrared IR-A 770–1400 nmIR-B 1.4–3.0 mIR-C 3.0 m–1 mm

Note: Boundaries between the bands provide a framework for addressing biological effects– but have no basis in fundamental physics.Actinic UV refers to the UV-B and UV-C bands because of their ability to cause chemical reactions.


December 2014

LASER (Light Amplification by Stimulated Emission of Radiation)

• UV, visible, or infrared (IR) radiation that propagates as a beam

• Characteristics– Low divergence– Monochromatic– Coherent– High intensity


December 2014

Nomenclature of ELF and RF Band Designations

Frequency Range Designation Abbreviation* <30 Hz sub-Extremely Low Frequency sub-ELF* 30–300 HzExtremely Low Frequency ELF* 300–3000 Hz Voice Frequency VF 3–30 kHz Very Low Frequency VLF 30–300 kHz Low Frequency LF 300–3000 kHzMedium Frequency MF 3–30 MHz High Frequency HF 30–300 MHz Very High Frequency VHF 300–3000 MHzUltra High Frequency UHF 3–30 GHz Super High Frequency SHF 30–300 GHzExtremely High Frequency EHF* The IEEE definition of band designations does not include VF, and defines ELF as 3–3000 Hz, and <3 Hz as ultralow frequency (ULF).ACGIH identifies the region 30 kHz and below as sub-radiofrequency (sub-RF). Microwave radiation (300 MHz to 300 GHz) is RF subset. 18Nonionizing Radiation Overview

December 2014

Quantities & Units

• Used in nonionizing radiation exposure limits• Many quantities because of different spectral regions

and interaction mechanisms• Legend for following table:

W= watt; cm = centimeter; J = joule; V = volt;

A = ampere; m = meter; mA = milliampere;

μT = microtesla; mG = milligauss; T = tesla;

G = Gauss


December 2014

Quantities Used in Exposure Guidelines*Spectral Region Quantity Unit

UV, IR, & Lasers* Irradiance (E) mW/cm2, μW/cm2

Radiant Exposure (H) J/m2; mJ/cm2

Radiofrequency (RF) E-field strength V/m; V2/m2

H-field strength A/m; A2/m2

Power density (S, W) mW/cm2

Specific absorption rate W/kg

Specific absorption J/kg

Induced / contact currents mA

ELF Electric-field strength V/m; kV/m

Magnetic flux density (B) μT; mG

Current density (J) mA/m2

Static fields Electric-field strength V/m

Magnetic-field strength T; G*For brevity, visible radiation & some laser radiation quantities are not included.


December 2014

Hierarchy of Potential Hazard Concern

• Lasers• Ultraviolet (UV)• Radiofrequency (RF) / microwave• Electric and magnetic fields (frequencies 30 kHz

and below)• Static fields (electric and magnetic)


December 2014

Ultraviolet Radiation Sources• Sunlight* – atmosphere opaque to wavelengths < 295 nm• Welding – gas-metal, gas-tungsten, plasma, & arc welding, and

CO2 laser welding plasma

• Low pressure mercury vapor lamps – primary emission wavelength 254 nm for germicidal applications

• Metal halide and mercury vapor lamps – for illumination• Tanning booths & beds* – primarily UVA with some UVB –

subject of FDA product performance standard• Blacklights* -- broadband source of UV and visible radiation – peak

output ~ 362 nm – non-destructive testing and entertainment applications

• Lasers – Excimer (KrF, ArF, XeCl), HeCd, frequency-tripled or quadrupled-Nd:YAG – micro-material processing & research

*Listed as carcinogenic to humans by the IARC and known to be human carcinogens by the NTP (13th ed.)


December 2014

The Sun – Significant UV Exposure Source


December 2014 Nonionizing Radiation Overview 24

UV Lamp Spectra


Target organs – eyes and skin (UV does not have deep penetration) Acute overexposure (delayed response: 2 to 12 or more hours; more

intense exposure – shorter response time)• Erythema (redness or burning of the skin)• Photokeratitis (inflammation of the cornea)• Photoconjunctivitis (inflammation of the soft tissue around the eye)

Chronic overexposure• Cataracts• Skin aging• Immunosuppression• Skin cancer (melanoma, non-melanoma)• Possible eye cancer• UV classified as Group 1 human carcinogen by the IARC**

Natural and synthetic photosensitizers increase UV’s potency in causing skin burns or cancer

• **IARC - International Agency for Research on Cancer

UV - Biological Effects


UV - Biological Effects

UV-C and UV-B wavelengths absorbed primarily by the cornea & conjunctiva (front of the eyeball & inner surface of eyelids)

UV-A wavelengths – potential hazard to lens & retina


Cover UVR in spectral band from 180-400 nm resulting in eye and skin exposure from the sun and all artificial UVR sources – except lasers.

UV radiation’s effectiveness at causing skin burns or corneal inflammation is wavelength dependent (for example, 270 nm is wavelength most effective in producing photokeratitis).

ACGIH Threshold Limit Values (TLVs) are harmonized with International Commission on Non-Ionizing Radiation Protection (ICNIRP) guidelines.

Guidelines based primarily on studies of acute human / animal exposures resulting in erythema, keratoconjunctivitis, & cataracts.

Not to be used for photosensitive individuals, those exposed to photosensitizing agents, or ocular exposure of individuals whose eyes lack lenses (aphakes).

UV - Exposure Guidelines


For broadband sources – UV incident on the eye must be weighted by a spectral effectiveness function to obtain the “effective irradiance.” Integral of the effective irradiance over time – (or, for constant irradiance, the product of the effective irradiance and exposure time) shall not exceed 3 millijoules per square centimeter (mJ/cm2) in one day

Eye (corneal) exposure guidelines are expected to be protective of all skin types in the absence of photosensitizers

To protect the lens and retina from UV-A, unweighted UV-A radiant exposure:• Should not exceed 1 J/cm2 for daily cumulative exposure time less than 17 minutes (1000 seconds)• Should not exceed 1 mW/cm2 for daily cumulative exposure time more than 17 minutes (1000 seconds)

UV Radiation TLVs


Flow Chart for UVR TLV


TLVs for UV Radiation


Actinic UV (200-315 nm) TLVs

Within an 8-hour period, exposure of unprotected skin or eye to actinic UV radiation should not exceed the values given in this table.


UVR Relative Spectral Effectiveness


UVR Exposure Duration Limits


Type of UVR-emitting equipment Process or area in which the equipment is used How operators interact with the equipment Number of potentially exposed employees Description of tasks involved Amount of time spent working around the equipment How the equipment is maintained

Basic Exposure Characterization

December 2014

Ultraviolet Radiation – Ancillary Hazards UV-C radiation at wavelengths less than 242 nm reacts

with oxygen to form ozone (local exhaust ventilation may be required)

Explosion – internal pressure of short arc lamps, even when cold, exceed one atmosphere – when under operation, internal pressure pf 10 to 20 atmospheres are possible (operate such lamps in special fixtures to contain glass shrapnel should a lamp explode; do not touch lamp surfaces as hot spots will be produced where there is skin oil contamination; do not operate lamps that are scratched or chipped)

Skin burns – from touching the surfaces of hot lamps


December 2014

UV – Exposure Controls

• Elimination / minimization of reflective surfaces from work area

• Enclosure of work operation behind opaque or absorptive materials

• Eyeglasses, goggles, faceshields with UV-absorbing lenses

• Protective clothing (tightly-woven materials)• Sunscreens (not protective against shorter wavelengths)


December 2014

Visible Radiation Sources

• Sun – all visible wavelengths transmitted by atmosphere

• Welding arcs – broadband visible emission – including blue light with potential photochemical retinal damage

• Lamps – photoflood, metal halide, and sunlamps: intense sources that may be rich in blue wavelengths (blue light)

• LEDs (light-emitting diodes) – indicators (e.g., vehicle tail lights), signs, and communcations

• Lasers – Gas (Ar, Kr, HeNe), Doubled-Nd:YAG, diode (GaAs, GaInAs, etc.)


December 2014

Infrared (IR) Sources

• Sun – near-infrared (IR-A)

• Incandescent sources – including heated elements (heated filaments & coils) and blackbody sources (furnaces, ovens, and coils)

• Industrial IR sources – steel mills, foundries, glass-making, drying equipment

• Lasers – neodymium: yittrium-aluminum-garnet (Nd:YAG), neodymium:yittrium lithium fluoride (Nd:YLF); carbon dioxide, laser diodes (GaAs, GaAlAs, InGaAs, etc.)


December 2014

Infrared (IR) Biological Effects

• Thermal burns of the cornea (IR-B and IR-C)

• Thermal lesions on the iris (IR-A at or above 4.2 J/cm2)

• Cataracts (IR-A and possibly IR-B)

• Retinal burns (IR-A)

• Retinal hemorrhaging (pulsed IR-A lasers)

• Thermal skin burns

• Skin vasodilation

• Increased skin pigmentation

• Skin pain / damage thresholds closely related (45Co or 113o F)

• Thermal stress


December 2014

Laser Radiation• Nd:Yag (neodymium:YAG) – Fundamental 1064 nm

wavelength may be frequency-doubled to 532 nm; include Q-switched lasers with short-duration (10 to 100 nsec) pulses. Material processing (e.g., cutting and welding) is primary industrial application; also research applications.

• CO2 (carbon dioxide) – Output at 10.6 µm. Industrial applications in material processing as well as human and veterinary medicine. Carbon dioxide laser radiation interaction with metals may produce broadband (plasma) radiation (potential UV-C, UV-B, and blue light exposure concerns).

• HeNe (helium neon) – primarily 633 nm output with scanning applications for alignment (pipelines, ceiling tile grids, other lasers) and universal product code reading


December 2014

Laser Radiation (continued)• Ar (argon) – ion gas laser with green (514 nm) and blue

(488 nm) spectral region output for use in entertainment (laser light shows), medicine (e.g., retinal spot welding and lesion removal), and research labs.

• Dye lasers – tunable output in the visible and IR-A (near infrared)

• Diode lasers – semiconductor lasers: some with output with shorter wavelengths (visible) and some with output with longer wavelengths (near-infared [IR-A] and mid-infared [IR-B]).


December 2014

While this can not really happen, one CAN get a thermal lesion on one's retina by staring long enough down the axis of a laser pointer's beam. Please remember that laser pointers are tools not toys!


December 2014

Unsafe & Illegal Laser Pointer Use (from: LaserPointerSafety.com)


December 2014

Airplane Cockpit Laser Pointer Illumination


December 2014

Laser Research Laboratory


December 2014

Lasers in Research Lab


December 2014

Laser-Containing Tool


December 2014

Lasers – Biological Effects

Laser Effects -- Wavelength dependent

(e.g., 400-1400 nm – retinal hazard region)

Eye injury• Retinal thermal burns, acoustic damage,

photochemical injury• Lens-related damage• Corneal damage

• Skin damage (thermal & photochemical)


Eye Anatomy


December 2014

Retinal Injury


Retinal Injury



December 2014

Optical Gain of the Eye

LensCornea

Iris

Aqueous

Ciliary MuscleChoroid Sclera

Optic Nerve

Optic Disk

Macula Lutea

Fovea Centralis

Pigment EpitheliumRetina

For wavelengths that focus on the retina, the optical gain of the eye is ~ 100,000 times: if irradiance at cornea is 1 mW / cm², then irradiance at the retina will be 100 W /cm².


December 2014

Viewing Conditions

LASER

Intrabeam - Direct (primary)

Beam

LASER

Intrabeam - Flat Surface Specular

Reflection

LASER

Intrabeam - Curved Surface Specular

Reflection

Curved mirror

Point Source Diffusion Reflection (Extended Source Viewing When Apparent Visual Angle

Exceeds Some Minimum)

LASER

visual angle



Laser Radiation Skin Penetration

Laser Safety-Related Parameters• Wavelength (Several thousand laser lines but only about 20

developed for routine applications)• Exposure duration• Radiant power (in watts or Φ) for continuous wave (CW) lasers• Beam divergence (in milliradians)• Exit beam diameter (in millimeters)• Pulse energy (joules J or Q), pulse repetition frequency (PRF or

F), & pulse width (in milli-, micro-, nano-, pico-seconds) for pulsed lasers

• Focal length, mode field diameter (single-mode fiber), & numerical aperture (multi-mode fiber) for fiber optic output

• Focal length & size of beam on lens for “laser on lens” output


American National Standards Institute (ANSI) – maximum permissible exposure (MPE) values per ANSI Z136.1 and other standards in Z136 series: MPEs depend on laser emission characteristics and viewing conditions

Federal Occupational Safety and Health Administration (OSHA) – General Duty Clause of OSH Act

U.S. Food and Drug Administration's Center for Devices and Radiological Health (CDRH)

International Electrotechnical Commission (IEC) [European]

Laser Safety Exposure Guidelines

Nonionizing Radiation OverviewDecember 2014 57

Laser Safety Standards• Federal OSHA (and Cal/OSHA) have some standards that

address laser use in construction and laser eye protection • The CDRH has the Laser Product Performance Standard in Title

21 Code of Federal Regulations (CFR) Subchapter J, Part 1040 – these regulations are mandatory for all laser products sold to end users in the United States.

• The IEC has a series of Laser Product Standards applicable to both manufacturers and users of lasers

• Efforts continue to harmonize the various sets of laser safety standards. For example, the most recent (2014) version of the primary ANSI laser safety standard (Z136.1) adopts the laser classification scheme found in its IEC laser safety standard counterpart.


Laser Safety Standards ANSI—most important series of voluntary U.S. national

consensus laser safety standards (periodically revised)– ANSI Z136.1-2014 Safe Use of Lasers– ANSI Z136.2-2012 Safe Use of Optical Fiber Communication

Systems Utilizing Laser Diode and LED Sources– ANSI Z136.3-2011 Health Care Facilities– ANSI Z136.4-2010 Measurements for Hazard Evaluation– ANSI Z136.5-2009 Educational Institutions– ANSI Z136.6-2005 Lasers Outdoors– ANSI Z136.7-2008 Testing & Labeling of Laser Protective

Equipment– ANSI Z136.8-2012 Research, Development or Testing– ANSI Z136.9-2013 Manufacturing Environments

ANSI laser safety standards under development: – ANSI Z136.10 Entertainment, Displays, & Exhibitions


December 2014 60

Laser Hazard ClassesClass Exposure Condition Control Actions Required

1 Eye safe, even with optical aids

None – except for enclosed Class 3B or 4

1M Class 1, except with optical aids

No optical aids; or aids adequately attenuated

2

(visible)

Safe for momentary viewing

0.25 sec. aversion response protective

2M

(visible)

Class 2, except with optical aids

No optical aids; or aids adequately attenuated

3R Marginally unsafe for intrabeam viewing

Limited controls (e.g. labels and training)

3B Unsafe for intrabeam viewing

LSO; harmful access preventing controls

4 Eye and skin hazard Restrict source output or prevent personnel access


December 2014

Lasers - Ancillary Hazards

– Electrical– Laser-generated air

contaminants– Collateral radiation (X-ray, UV, visible, RF,

plasma radiation)– Fire– Explosion– Compressed gases

– Laser dyes and solvents

– Robotic mechanical – Noise– Waste disposal– Limited work space– Ergonomics

Per ANSI Z136.1-2007, Section 761Nonionizing Radiation Overview

December 2014

Lasers – Control Measures

• Prevent access to class 3B / 4 laser output (interlocks on lab doors or tools with these higher hazard lasers inside)

• Confinement of beam paths to optical tables and minimization of stray beams

• Personal protective equipment – Laser eye protection with adequate attenuation (optical density)

at the wavelengths or wavelength ranges in use (must provide adequate visible luminous transmission) – particularly during beam path alignment

– Skin protection if UVR emissions are present

• Other controls that address ancillary hazards present


Diffuse reflection OD—minimum needed for alignment eye protection (generally based on 600-second exposure duration)

Intrabeam OD—required for "full" protection (for visible wavelengths can be based on short aversion response exposure durations)

OD = Log10(Hp/MPE)

• Hp = Potential eye exposure expressed in same units as MPE

• MPE = maximum potential exposure

Optical Density


December 2014

Radio-Frequency Radiation (RF)*• Dielectric heaters – operate at 10 – 100 MHz (many at 27 MHz) to

heat dielectric materials (e.g., plastics) to cure, bake, mold seal, or emboss; unshielded units may produce overexposures.

• Semiconductor manufacturing tools – sputterers, plasma etchers• Induction heaters – operate at < 500 MHz to harden, weld, forge,

found, solder, anneal, or temper conductive materials.• Broadcasting – AM radio (535-1605 kHz), FM radio (88 – 108 MHz),

VHF TV (54-72 MHz, 76-88 MHz, 174-216 MHz) and UHF TV (470-890 MHz)

• Communications – Fixed systems (satellite, microwave relay), mobile devices (cellular, wireless, walk-talkie, CB)

• Radar – pulsed microwave emissions; commercial, military, marine & traffic control radars. Most in SHF spectral region.

• Diathermy – Shortwave (13 & 27 MHz) & microwave (915 & 2450 MHz) used to heat tissues: both pulsed and CW mode.

* 30 kHz – 300 GHz listed as possibly carcinogenic to humans (IARC Group 2B)


December 2014

Sputtering Device


December 2014

Typical Emissions – Various RF Sources


December 2014

RF – Biological EffectsFrequency (thus, wavelength) dependent

Thermal effects• Behavioral/other nervous

system effect (reversible)• Reproductive &

developmental effects

(animal data only)• Cancer (animal data only –

inconclusive)

•Ocular effects (restrained

animals only)• Skin burns (delayed & similar to sunburn)• MW clicking – cochlear

thermal elastic expansion &

contraction

Note: Specific non-thermal effect mechanism not identified – no effects clearly linked to non-thermal exposures


December 2014

Exposure Guidelines – RF & LasersRadio-frequency (RF)

RadiationLaser Radiation

Maximum Permissible Exposure (MPE) values for controlled environments

Per IEEE Std. C95.1-2005

MPE values

Per ANSI Z136.1depending on

emission characteristics and viewing conditions

Action Levels• C95.1 Lower tier limits• Gen. public guidelines

(FCC & ICNIRP)• One-fifth of ACGIH TLVs


December 2014

RF – Exposure Guidelines

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Maximum Permissible Exposures for RF in Controlled Environments


December 2014

RF – Exposure Guidelines


December 2014 71

RF Sources - Ancillary Hazards– Trip hazards– Welding/cutting

operations– Heat stress– Toxic chemicals/gases– Cooling refrigerants– Optical radiation

sources, coherent (lasers) and non-coherent sources

– Electric shock– Ionizing radiation– Mechanical– Eye hazards– Heat exchange

systems– Fall from heights

and/or through openings

– Confined space entry

Per IEEE C95.7, Section 4.7Nonionizing Radiation Overview


RF Exposure Control CategoriesRFSP

CategoryExposure Condition Control Actions

Required

1 Action level not exceeded

None; except when action level exceeded

2 Possible action level, but not exposure limit, exceedance

Some program elements, signage,

time averaging

3 Exposure limit exceedance w/o

mitigating controls

More program elements, RFSO,

more training,

4 Exposure limit exceeded in

accessible areas

Restrict source output or prevent personnel access


Radio Frequency Safety Program (RFSP) Elements per IEEE C95.7

• Administrative (includes designation of Radio Frequency Safety Officer [RFSO])

• Identification of Potential RF Hazards• Controls• Personal Protective Equipment (PPE)• Training• RFSP Audit• Ancillary Hazards

December 2014

Extremely Low Frequency (ELF)

• Power-frequency fields – electric and magnetic fields* associated with the generation, transmission, distribution and use of electricity: 60 Hz in U.S. & small part of Japan; 50 Hz elsewhere.

• Degaussing – ELF magnetic fields may be used to demagnetize material: used for magnetizable media (e.g. storage tapes), computer screens, airplanes, and naval vessels.

• Welding – Electric arc and resistance welding.

• Furnaces – Electric furnaces (ladle, arc, induction, and channel) used for hardening, smelting, and heat-treating conductive materials.

*30 kHz – 300 GHz listed as possibly carcinogenic to humans (IARC Group 2B)


TLVs – Sub-RF Magnetic FieldsFrequency Range TLV – ceiling values in mT;

(current limits in mA)

1 to 300 Hz Whole-body exposure: 60 / f

1 to 300 Hz Arms and legs: 300 / f

1 to 300 Hz Hands and feet: 600 / f

300 Hz to 30 kHz Whole & partial body: 0.2

1 Hz to 2.5 kHz Point contact current limit: 1.0

2.5 kHz to 30 kHz Point contact current limit: 0.4fPacemaker and medical electronic device wearer exposure should be maintained at or below 0.1 mT at power frequencies.Source: ACGIH 2010 TLVs for Sub-Radiofrequency [30 kHz and belowmT = millitesla; mA = milliamperes; f = frequency in Hz (kHz for current limit)


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EMF in the Electromagnetic Spectrum

Source: National Institute of Environmental Health Sciences (NIEHS): EMF Questions and Answers: Electric and Magnetic Fields Associated with Electric Power. NIEHS, 2002.


Exposure Limits – Power Frequency Fields

Sources: IEEE C95.6-2002 Standard for Safety Levels with Respect to Human Exposure to Electromagnetic Fields, 0 – 3 kHz and ACGIH 2014 TLVs for Sub-Radiofrequency (30 kHz and below) and Static Electric Fields


December 2014

Static Fields Sources

• Current-intensive processes – aluminum extraction and chlor-akalai plants. Static magnetic fields

• MRI and NMR – magnetic resonance imaging (MRI) in healthcare environment and nuclear magnetic resonance (NMR) as analytical method; can also produce pulsed magnetic fields and radio-frequency (RF) fields

• Superconducting magnets – static magnetic fields in analytical labs.

• Televisions and computer monitors – operation of devices that incorporate cathode ray tubes (CRTs) that produce a static electric fields at the screen.


December 2014

Magnetic Fields


December 2014

Static Field Sources


Nonionizing Radiation Overview 81

TLVs – Static Magnetic Fields

Exposure Ceiling Value

Whole body (general

workplace)

2 T

Whole body (special worker training and

controlled work environment)

8 T

Limbs 20 T

Medical device wearers 0.5 mT

Source: ACGIH 2014 TLVs for Static Magnetic FieldsT = tesla mT = millitesla

December 2014

CAUTIONStrong Magnetic Field

People with ferromagnetic or electronic medical implants must stay away [at least __ feet ] from the sides of this tool.Damage to watches, instruments and magnetic media possible.


CAUTIONStrong Magnetic Field

People with ferromagnetic or electronic medical implants should not enter this lab area as magnetic field strengths inside it can exceed 5 Gauss.Damage to watches, instruments and magnetic media possible.December 2014 Nonionizing Radiation Overview 83

December 2014

MRI Precautions


Nonionizing Radiation Overview 85

Magnetic Field Controls

• Establishing controlled areas and restricting access into those areas

• Field cancellation using closely spaced conductors, have grounding exit a building where electrical service enters it, eddy current production with nonpermeable metals.

• Shielding enclosure with relatively high permeability metals (special ferrous alloys)

• Administrative controls: distance restrictions, warning signs, and information & training

December 2014

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Electric Field Controls

• Establishing controlled areas and restricting access into those areas

• Proper grounding to counter indirect coupling• Shielding with grounded conductive solid or

perforated sheeting; perforation sizes < 0.25 wavelength of frequencies being shielded

• Administrative controls: approach distance restrictions, warning signs, and information & training


December 2014

Electromagnetic Spectrum

NIR portion of spectrum covers 15 orders of magnitude in frequency units.


December 2014

Exposure Defining Information• Ultraviolet (UV) – source type; spectral distribution; reflection

potential; photosensitization potential

• Laser – wavelength; continuous wave (CW); radiant power; pulsed operation; energy / pulse; pulse repetition frequency; pulse width (duration); direct beam NHZ (nominal hazard zone); beam divergence; emergent beam diameter; focused beam NHZ; focal length; beam diameter incident on lens; reflection potential; photosensitization potential

• RF – frequency; near-field aperture antenna; power; antenna area; gain, distance from emitter; pulsed emitters; duty cycle; potential for reflection; potential for hot-spot formation; conductive surfaces that pose contact current hazard

• ELF – frequency; users of medical devices; whole-body and/or partial-body exposure

88

From: Hitchcock, R.T.: Chapter 15 in A Strategy for Assessing and Managing Occupational Exposures, 3rd Ed. (AIHA, 2006)


December 2014

ACGIH Threshold Limit Values (TLVs)

• Optical Radiation– Light (including Blue Light) and Near-IR– Ultraviolet Light– Lasers (see ANSI Z136 standard series)

• Radiofrequency / Microwave Radiation• Subradiofrequency (30 kHz and below) Electric

Fields & Static Electric Fields• Subradiofreqency (30 kHz and below) Magnetic

Fields• Static Magnetic Fields


December 2014

Additional Information Sources• AIHA Nonionizing Radiation Committee Website -

https://www.aiha.org/get-involved/VolunteerGroups/(click on Nonionizing Radiation in list of AIHA Volunteer Groups–Quick Reference Sheets (Ultraviolet Radiation, Lasers, Radiofrequency and Microwave Radiation, Blue Light Hazard, Static Magnetic Fields

• Health Physics Society - http://www.hps.org/• ACGIH Documentation of the Threshold Limit Values for

Physical Agents - http://www.acgih.org/TLV/• Radiofrequency Toolkit for Environmental Health

Practitioners


https://www.aiha.org/get-involved/VolunteerGroups

http://www.hps.org/

http://www.acgih.org/TLV/

December 2014

Additional Information Sources• International Commission on Non-Ionizing Radiation

Protection (ICNIRP) - http://www.icnirp.org/– Guidelines on different NIR frequency and wavelength segments

• IEEE Standards Association - http://standards.ieee.org/– IEEE C95.1 – 2005 Safety Levels with Respect to Human

Exposure to Radio Frequency Electromagnetic Fields, 3 kHz to 300 GHz

– IEEE C95.7 – 2014 IEEE Recommended Practice for Radio Frequency Safety Programs, 3 kHz to 300 GHz

• International Agency for Research on Cancer (IARC) - http://www.iarc.fr/– Monographs containing evaluations of carcinogenic risk to

humans posed by occupational and environmental exposure to NIR and other agents


http://www.icnirp.org/

http://standards.ieee.org/

http://www.iarc.fr/

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References• Peter H. Wald and Greg M. Stave (eds.): Physical and

Biological Agents of the Workplace, 2nd Edition. New York: John Wiley & Sons, 2002.

• T.P. Fuller and R.T. Hitchcock: Chapter 25, Nonionizing Radiation in The Occupational Environment: Its Evaluation, Control, and Management, 3rd Edition. Fairfax, VA: AIHA, 2011.

• National Institute of Environmental Health Sciences (NIEHS): EMF Questions and Answers: Electric and Magnetic Fields Associated with Electric Power. NIEHS, 2002. http://www.niehs.nih.gov/health/docs/emf-02.pdf

• Miller, G.C. with revision by M. Yost: Chapter 11, Nonionizing Radiation in Fundamentals of Industrial Hygiene, 5th Edition. National Safety Council, 2002.


http://www.niehs.nih.gov/health/docs/emf-02.pdf

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References• American Conference of Governmental Industrial

Hygienists (ACGIH): Threshold Limit Values® for Physical Agents. Cincinnati, OH: ACGIH, 2014.

• American Industrial Hygiene Association (AIHA): General Concepts for Nonionizing Radiation Protection. Fairfax, VA: AIHA, 1998.

• Patterson, R.M., and R.T. Hitchcock: Radio-Frequency and ELF Electromagnetic Energies. New York: Van-Nostrand Reinhold, 1995.

• Radiofrequency Toolkit for Environmental Health Practitioners (BC Centre for Disease Control & National Collaborating Centre for Environmental Health, 2013) http://www.bccdc.ca/healthenv/ElectromagFields/RadioFrequency/default.htm


http://www.bccdc.ca/healthenv/ElectromagFields/RadioFrequency/default.htm

http://www.bccdc.ca/healthenv/ElectromagFields/RadioFrequency/default.htm

December 2014

Concluding Remarks• The nonionizing radiation (NIR) portion of the electromagnetic

spectrum is very broad.

• The NIR spectral region includes ultraviolet, visible, infrared, radio-frequency (RF), and extremely low frequency (ELF) radiation as well as laser radiation.

• The use of NIR in our society provides not only benefits but also potentially significant hazards.

• Some NIR sources pose significant ancillary hazards – hazards unrelated to direct NIR exposure.

• NIR control measures include exposure avoidance, exposure duration reduction, source isolation (e.g., source approach distance restrictions), containment, and attenuation as well as provision of information (e.g., signage) & training.


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Thank you for your kind attention!!!

Should you have an interest in joining the AIHA Nonionizing Radiation Committee – or if you have questions after this meeting,

I may be contacted at:[email protected]


Documents

Nonionizing Radiation (NIR) Overview Stephen Hemperly, MS, CIH, CSP, CLSO Local Section Regional Representative AIHA Pacific Region Rio Grande AIHA Fall