1. Ionizing & Non-ionizing Radiation ENGR 4410 – INDUSTRIAL HYGIENE INSTRUMENTATION October 23, 2013
Janet M. Gutiérrez, DrPH, CHP, RRPT
Radiation Safety Program Manager
Environmental Health & Safety

2. Speaker Biography
Janet M. Gutierrez is manager of the Radiation Safety Program at The University of Texas Health Science Center at Houston. She is a Certified Health Physicist (CHP) and a Registered Radiation Protection Technologist (RRPT). In August 2011, she received a Doctorate in Public Health from the The University of Texas at Houston School of Public Health (UT SPH), and in 2005, she received a M.S. in Environmental Sciences / Industrial Hygiene from UT SPH as well. In 1998, Janet received a B.S. in Radiological Health Engineering from Texas A&M University in College Station, TX.

3. Speaker Biography
Travis Halphen is a Safety Specialist in the Radiation Safety Program at The University of Texas Health Science Center at Houston (UTHSC-H). He is currently seeking his MPH in Environmental Health and Occupational Safety from University of Texas School of Public Health (UT SPH) and on May 2006 he received a Bachelors in Medical Physics from Louisiana State University. He was Assistant Radiation Safety Officer and Laser Safety Officer at Kansas State University from 2006 to 2008 before he ended up at his current position at UTHSC-H

4. Ionizing vs. Non-ionizing Radiation
Electromagnetic Spectrum
Nonionizing radiation is greater than 100 nm in wavelength

5. Radiation

6. Ionizing & Non-ionizing Radiation
Units
Decay
Inverse Square Law
Shielding, HVL, TVL
Instruments
Dosimetry
Biological Effects
Regulations
Practice Problems
Types
Biological Effects
Regulations/Guides

7. What is Radiation?
Radiation is energy transmitted by particles or electromagnetic waves
Radiation can be ionizing or non-ionizing

8. Basic Concepts Radiation: energy
Ionizing vs. Non-Ionizing: enough energy to eject orbital electrons
Radioactivity: excess nuclear energy

9. Radioactivity
Radioactivity is the natural property of certain nuclides to spontaneously emit energy, in the form of ionizing radiation, in an attempt to become more stable.

11. Basic Concepts Radionuclide Nuclide
Isotopes have the same Z and a different A;
10C,11C, 12C, 13C, 14C
Isobars have the same A and a different Z;
14N, 14O; 15N, 15C
Isomers have the same A and the same Z;
99mTc, 99Tc
Isotones have the same N and a different A;
14O,13N,12C,11B,10Be,8Li

12. Basic Concepts Types of radiation: Alpha: particulate, massive
Beta: particulate, penetrating
Gamma: electromagnetic, penetrating
X-ray: electromagnetic, penetrating
Neutron: particulate, no charge

13. Alpha (α)
Needs at least 7.5 MeV energy to penetrate nominal protective layer of skin (7 mg/cm2)
Most α less than this energy, so can not penetrate skin
Range in air
Range (cm) = 0.56E for E< 4 MeV
Range (cm) = 1.24E for E> 4 MeV

14. Beta (β)
Need at least 70 keV energy for beta to penetrate nominal protective layer of skin
βave = 1/3 βmax
Range in air
Range is ~ 12 ft / MeV
Bremsstrahlung for high energy beta & high Z material
Ex. P-32 and Lead

15. Gamma (γ) Photoelectric Compton Scattering Pair Production Photon
X-ray
Gamma ray

16. Neutrons (n) Often expressed in n / cm2sec (flux)
Thermal neutrons = eV
Slow neutrons = 1 eV – 10 eV
Fast neutrons = 1 MeV – 20 MeV
Relativistic neutrons = > 20 MeV
U-238 & U-235

17. Shielding Examples

18. Shielding for Multiple Types of Radiation
High Energy Betas
Bremstrahlung
Neutrons
Gammas

19. Units Activity: Curie (Ci) 3.7 x 1010 disintegrations per second
SI: Becquerel 1 dps
Exposure: Roentgen
SI: C/kg
Absorbed Dose: Rad (Roentgen Absorbed Dose)
SI: Gray, 1Gy = 100 Rad
Risk: Rem (Roentgen Equivalent Man), Rad x QF
SI: Sievert, 1 Sv = 100 Rem

20. Quality Factors

21. Half-life
Half-life - the amount of time required for 1/2 of the original sample to decay
The half-life is constant for each radionuclide and varies due to the nuclear structure.

22. Radioactive Decay
Is the process by which the amount of activity of a radionuclide diminishes with time.
Examples:

23. Radioactive Decay Formula
Variables
A  Activity at time t
A0  Original Activity
t  Time
  Decay Constant
T1/2 Half Life
Constants
ln 2 
e1 

24. Concepts Radioactive Decay: A = Aoe-λt Inverse Square Law
A = λN
λ = / T1/2
Inverse Square Law
Shielding I = IoBe-t

25. Annual US Average Dose from Background Radiation was
Total US average dose equivalent = 360 mrem/year
Total exposure
Man-made sources
Radon
Internal 11%
Cosmic 8%
Terrestrial 6%
Man-Made 18%
55.0%
Medical X-Rays
Nuclear
Medicine 4%
Consumer
Products 3%
Other 1%
11%

26. Annual US Average Dose from Background Radiation Now is 625 mrem
National Average Dose is US is 625 mrem,
with medical being the largest type of increase.

27. Ionization of Gas – Radiation Detector
A = recombination
B = ionization
C = proportional
D = limited proportional
E = Geiger Muller
F = continuous discharge

28. Monitoring Instrumentation Gas filled Solid scintillator
Liquid scintillation

29. Monitoring Dosimeters Film badges: beta, gamma, x-ray
Permanent record
Subject to fading
Thermoluminescent dosimeter (TLD): beta, gamma, x-ray
No permanent record
Can be used for long term use
Pocket ion chamber: gamma, x-ray
Immediate readout
Shock sensitive

30. Biological Effects Radiation Effects on Cells:
Somatic (early, delayed) &
Genetic Dose Responses
Linear, Linear Quadratic, Threshold

31. Stochastic and Non-stochastic Effects
Dose increases the probability of the effect
No threshold
Any exposure has some chance of causing the effect
Cancer
Non-stochastic effects
Dose increases the severity of the effect
Threshold
Effects result from collective injury of many cells
Reddening, cataract, skin burn
Stochastic: Chance/Probability (cancer)
Non-stochastic: Related directly to dose - acute (burns, reddening)

32. Biological Effects
Assumptions Used for Basis of Radiation Protection Standards
No Threshold Dose, Risk with Given Dose Increases With Increasing Dose Received, Acute vs. Chronic Exposures Not Considered, i.e. Repair

33. Biological Effects Prenatal Exposures
Law of Bergonie & Tribondeau (1906):
Cells Tend to be Radiosensitive if They Have Three Properties:
A) Have a High Division Rate
B) Have a Long Dividing Future
C) Are of an Unspecialized Type

34. Most and Least Radiosensitive Cells
Low Sensitivity
Mature red blood cells
Muscle cells
Ganglion cells
Mature connective tissues
High Sensitivity
Gastric mucosa
Mucous membranes
Esophageal epithelium
Urinary bladder epithelium
Very High Sensitivity
Primitive blood cells
Intestinal epithelium
Spermatogonia
Ovarian follicular cells
Lymphocytes
esOfogal
spermAtogOnia

35. Acute Radiation Syndromes
Occurs if specific portions of body are exposed
Not likely unless major organs involved
3 ARS syndromes:
Hematopoietic (blood/bone marrow)
rad
Treatment: transfusions, antibiotics, bone marrow transplant
Gastrointestinal (intestinal lining)
rad
Death likely if dose >1000 rad
Treatment: make individual comfortable
Central Nervous System (brain)
2000 rad or more
Death likely within days
H: Blood cells (most sensitive)
G: GI cells (very sensitive)
CNS: Brain and muscle cells (least sensitive)
Sensitive organ: blood, intestinal lining, brain

36. LD50 for Humans
Dose of radiation that would result in 50% mortality of in the exposed population within 30 days of exposure with NO medical treatment
LD50 for Humans is 300 to 500 rad

37. Risks of Radiation Exposure
Low level (< 10,000 mrem) radiation
Only health effect: cancer induction
Average occupational dose to research and lab medicine personnel: <10 mrem/yr
Amount is comparable to:
6 cigarettes/yr
Driving 1,000 miles
Living in a stone or brick home for 2 months
Avg occ dose to RESEARCH AND LAB medicine personnel

38. Regulations / Guidelines
NRC
Agreement States
NCRP
ICRP
ALARA Program

39. Exposure Limits Regulations: NRC 10 CFR 20 Note old: New:
Whole body: 1.25 rem/quarter
Skin: 7.5 rem/quarter
Extremities rem/quarter
New:
Committed Dose Equivalent (CDE)
Dose to a particular organ:
Internal + External ≤ 50 rem

40. Exposure Limits Committed Effective Dose Equivalent (CEDE)
Dose to a particular organ or organs with weighting factor:
Internal + External ≤ 5 rem
Deep Dose Equivalent (DDE)
Dose at a depth of ≥ 1 cm:
Internal + External ≤ 5 rem (Eye ≤ 15 rem)
Shallow Dose Equivalent (SDE)
Dose to skin or extremity:
External ≤ 50 rem

41. Exposure Limits Total Effective Dose Equivalent (TEDE)
Sum of dose from external and internal, including weighting:
Internal + External ≤ 5 rem
Effective Dose Equivalent
Dose to organ or organs over one year period
Total Organ Dose Equivalent
Dose to organ from both internal and external:
Internal + External ≤ 50 rem
Exposure to Fetus (Declared Pregnancy) .5 Rem/9 months

42. Other Useful Information
6CE rule
Efficiency = c/d, usually in percent
Effective half life:
Stay time = dose / dose rate
REMEMBER UNITS!

43. Internal advisory body for ionizing radiation
Internal advisory body for ionizing radiation
ICRP Publications (examples)
 ICRP 84, Pregnancy and medical radiation
 ICRP 85, Interventional radiology
 ICRP 86, Accidents in radiotherapy
 ICRP 87, CT dose management
 ICRP 93, Digital radiology

44. National Council on Radiation Protection and Measurements
formulate and widely disseminate information, guidance and recommendations on radiation protection and measurements which represent the consensus of leading scientific thinking
publication of NCRP materials can make an important contribution to the public interest.
NCRP 148 – Radiation Protection in Veterinary Medicine
NCRP 138 – Management of Terrorist Events Involving Radioactive Material*
NCRP 134 – Operational Radiation Safety Training
NCRP 120 – Dose Control at Nuclear Power Plants
NCRP 115 – Risk Estimates for Radiation Protection

45. Control Programs for Sources of Radiation
Sealed Sources
Radiation-Producing Machines
Radioisotopes
Radioactive Metals
Criticality
Plutonium

46. Control Programs for Sources of Radiation
Operational Factors
Employee Exposure Potential
External Hazards
Internal Hazards
Records

47. Common Radionuclides Sealed sources
Cs-137, Co-60, Ir-192, Am-241, Kr-85, Sr-90, Po-208
Liquid radioactive material for research
P-32, P-33, S-35, H-3, C-14

48. Radiation Practice Problems Ionizing Radiation

49. Radiation Practice Problems
1. Iodine-131 has a radiological half life of 8 days. If a source originally contained 25 mCi how much remains after 18 days?

50. Radiation Practice Problems
2. Two measurements are taken on an unknown radiation source. The first was 1.3 mCi, and the second, taken 15 minutes later, was 0.05 mCi. What is the half life of this material?

51. Radiation Practice Problems
3. What is the exposure rate from a 15 Ci Cs-137 source at a distance of 1 foot? (Cs-137 gamma energy MeV) How about 10 feet?

52. Radiation Practice Problems
4. How long can a worker stay 10 feet away from a 15 Ci Cs-137 source without exceeding an administratively established quarterly dose limit of 1250 mrem?

53. Non-ionizing Radiation

54. What is Radiation?
Radiation is energy transmitted by particles or electromagnetic waves
Radiation can be ionizing or non-ionizing

55. Definition
Non-Ionizing Radiation = Radiation that does not cause ionization
Types of non-ionizing radiation include:
1. Ultraviolet (UV) light
2. Visible light
3. Infrared (IR) light
4. Microwaves
5. Radiowaves

56. Positive and negative charges cancel
Let’s Review – The Atom
In their normal state, atoms are electrically neutral (no net charge)
# protons = # electrons
An atom that has gained or lost electrons is called an ion
Positive and negative charges cancel

57. The Ionization Process
An in-coming photon interacts with an orbital electron
The electron is ejected from the atom, and the atom gains a net positive charge.
The photon generally transfers its energy to the electron and disappears.
The in-coming photon must have enough energy to knock the electron out of its orbit. (The energy of the photon must be greater than the binding energy of the electron.) I think the minimum energy is about 10 eV…check me on that.
Incident photon
Ejected electron

58. Non-Ionizing Radiation
Non-ionizing radiation is electromagnetic in nature:
This means it has characteristics of both waves and particles
However, non-ionizing radiation behaves primarily as a wave
Known as “wave-particle duality.”

59. Electromagnetic Spectrum
The electromagnetic spectrum covers an entire range of electromagnetic radiation
Which of these are considered to be non-ionizing?
Electromagnetic energy is present everywhere and exists over a VERY wide energy range. It extends over more than 25 orders of magnitude!
Electromagnetic radiation is measured in terms of energy (eV), wavelength (meters), and frequency (Hz).
The higher the energy, the higher the frequency and the shorter the wavelength (In other words, as the energy increases, the waves move faster and get closer together). Example: gamma rays have the shortest wavelength, so they also have the highest energy and frequency.

60. Electromagnetic Spectrum
Non-ionizing

61. Types of Non-Ionizing Radiation
Ultraviolet (UV) light
Visible light
Infrared (IR) light
Microwaves
Radiowaves

62. Non-Ionizing Radiation Terms
Wavelength
Frequency
Energy
10-18 m
3x1026 Hz
1.24x1012 eV
10-10 m
3x1018 Hz
1.24x104 eV
10-6 m
3x1014 Hz
1.24 eV
102 m
3x106 Hz
1.24x10-8 eV
Terms
Energy
Frequency
Wavelength

63. Ultraviolet (UV) Light
Ultraviolet light has a wavelength on the order of nanometers (nm)
This is the shortest wavelength of all non-ionizing radiations
1 nanometer is 10-9 meters (very small!)
Remember, shortest wavelength means it also has the highest frequency and highest energy of all non-ionizing radiations

64. Ultraviolet (UV) Light
Ultraviolet light cannot be seen by the human eye
It is divided into 3 regions
UVA (most energetic)
UVB
UVC (least energetic)
UV light is divided into the regions based on energy and wavelength.

65. Sources of Ultraviolet Light
UV light is emitted naturally by the sun and stars
It is produced artificially by electric lamps and light bulbs
                            

66. Is Ultraviolet Light Dangerous?
All UV light can damage skin and eyes
Over-exposure can lead to sunburn and various kinds of cancers, including melanomas
It can also lead to weakening
of the immune system
UVA rays, which are not absorbed by the ozone layer, penetrate deep into the skin.
UVB rays, which are partially absorbed by the ozone layer, mostly impact the surface of the skin and are the primary cause of sunburn.

67. Is Ultraviolet Light Dangerous?
UV damage to fibrous tissue is often described as “photoaging”
Photoaging makes people look older because their skin looses its tightness and it wrinkles
UVA rays contribute most heavily to premature aging.
Up to 90 percent of all visible skin changes commonly attributed to aging are caused by sun exposure.
However, it is interesting to note that an estimated 80 percent of a person’s sun exposure occurs before age 18.

68. UV Effects by Region UV-A (400-300 nm) UV-B (320-280 nm)
Pigmentation of skin or suntan
UV-B ( nm)
Erythemal region
Sunburn of skin
Absorbed by cornea of eye (welder’s flash)
UV-C ( nm)
Bacterial or germicidal effect

69. Protective Measures
Ensure that skin and eyes are adequately protected (sunscreen, sunglasses, clothing)
Never look directly at a source
Operate UV lamps in light-tight conditions
The earth’s atmosphere naturally filters out most of the UV radiation from space.
The best way to use UV lamps is to ensure that they only operate in an enclosed space. Dark walls will absorb the light.

70. Visible Light
The wavelength of visible light ranges from nanometers
Visible light occupies the smallest segment of the electromagnetic spectrum

71. Visible Light Visible light is comprised of various colors
The separation of visible light into its different colors is known as dispersion

72. Visible Light Each color is characteristic of a different wavelength
The color “indigo” has been dropped
Violet has the shortest wavelength (highest frequency)
Red has the longest wavelength (lowest frequency)

73. Black vs. White
Technically speaking, black and white are not colors at all
Black is the absence of color
White is the combination of all colors

74. Visible light health effects
Retinal burns
Color vision
Thermal skin burns

75. Infrared (IR) Light
The wavelength of infrared light ranges from microns
When an object is not quite hot enough to radiate visible light, it will emit most of its energy in the infrared
1 micron (1 micrometer) is 10-6 meters. This is one-millionth of a meter.

76. Sources of Infrared Light
Any object which has a temperature above absolute zero radiates in the infrared
Even objects we think of as being very cold, such as an ice cube, emit infrared light
The picture on the right is a thermal IR image of a person holding a burning match.
The yellow-white areas are the warmest, and the purple areas are the coldest

77. Sources of Infrared Light
Even humans and animals emit infrared radiation
Humans, at normal body temperature, radiate most strongly in the infrared at a wavelength of about 10 microns.
The image to the right shows a cat in the infrared.
Again, the yellow-white areas are the warmest, and the purple areas are the coldest.

78. Visible Light vs. Infrared Light
Some animals can “see” in the infrared
These images give an idea of how different the world would look if we had infrared eyes
For example, snakes can see in the infrared. Seeing in the infrared allows them to detect warm blooded animals.
The image on the left is a visible view of Seattle.
The image on the right is an infrared view of Seattle.
If we could see in infrared, we would be able to see in the dark (you could see the person sitting next to you even if the room were completely dark)
– infrared light – scroll down to “What is infrared?”

79. Is Infrared Light Dangerous?
Heating of tissues in the body is the principal effect of infrared radiation
Excessive infrared radiation can result in heat stroke and other similar reactions, especially in elderly or very young individuals

80. IR Effects by Region IR-A (0.75 – 2.5 nm) IR-B (2.5 – 5 nm)
Penetrates skin to some extent
Penetrate eyes to retina
IR-B (2.5 – 5 nm)
Almost completely absorbed by upper layers of skin & eyes
IR-C (5-300 nm)
Thermal burns on skin & cornea
Cataracts (glass blowers)

81. Microwave Radiation
The wavelength of microwave radiation ranges from about 10 microns to 1 meter
Microwaves have very low energies and very long wavelengths

82. Microwave Radiation Microwave radiation has many uses, including:
Cellular phones
Highway speed control
Food preparation
Microwaves interact most easily with objects of the same size, such as hot dogs or hamburgers.

83. Limit for Microwave Ovens
5 mW/cm2 at 5 cm from surface

84. Is Microwave Radiation Dangerous?
Exposure to very high intensity microwaves can result in heating of tissue and an increase in body temperature (thermal effects)
At low levels of exposure, the evidence for production of harmful effects (non-thermal effects) is unclear and unproven
The non-thermal effects seen in low level exposure studies have not been reproducible.
Although the evidence is unclear and unproven, products such as cell phone “brain guards” have still begun to appear on the market.

85. Is Microwave Radiation Dangerous?
Currently, exposure limits are based on preventing only thermal effects
Further research is needed in order to learn more about non-thermal effects

86. Radiofrequency (RF) Radiation
The wavelength of RF radiation (radiowaves) is greater than 1 meter
That’s a long wavelength.
Photons of radio and TV, whose wavelengths are measured in meters, interact with metal rods or wires called antennae.

87. Radiofrequency (RF) Radiation
Both microwaves and radiowaves are used in communication
As a result, there is considerable overlap between what is identified as a radiowave and what is identified as a microwave

88. Is RF Radiation Dangerous?
As with infrared light and microwave radiation, the primary health effects of RF radiation are considered to be thermal
RF radiation may penetrate the body and be absorbed in deep body organs without the skin effects, which can warn an individual of danger
As with microwaves, more research is needed to understand non-thermal effects.

89. Static Magnetic Field Effects at Levels Below 0
Static Magnetic Field Effects at Levels Below 0.5 mT and Greater Than 0.5mT
Nuclear Magnetic Resonance Imaging (NMR)

90. Static Magnetic Fields Introduction
Nuclear Magnetic Resonance Imaging
Increasingly used in Biomedical Research
in vivo analysis
effectively displays soft tissue contrasts
MRI is unobstructed by bone

91. Safety Concerns with Static Magnetic Fields
Attraction of Loose Ferromagnetic Materials
Surgical Implants
torqued, dislodged or rotated
Pacemaker Interference
Typically Seen Above 0.5 mT (5 Gauss)

92. SMF Exposure Limits / Guidelines
ICNIRP
200 mT
Whole body (averaged for day)
5000 mT
Limbs/extremities (ceiling)
40 mT
Continuous general public exposure
US FDA CDRH
4000 mT
Routine Patient Ceiling
ACGIH
60 mT {2000 T}
Whole body (8hr-TWA) {Ceiling}
600 mT {5000 T}
Limbs (8hr-TWA) {Ceiling}
0.5 mT
Medical electronic devices

93. NMR Mapping 0.5 mT

94. Issues with Static Magnetic Fields < 0.5 mT:
Space constraints impacts all involved
Concerns of stopping attention at levels below 0.5 mT
Impacts finite radiation protection programs resources
Facility Incompatibilities

95. SMF Affects Below 0.5 mT

96. SMF Problems Frequently Occurred
Screen “jitter”
Other electronic interference
Perceive Problem = Risk
Dynamic Situation
Can lead to other problems

97. SMF Recommendations Move “General Public” limit farther back
Move equipment to lower field levels
Solicit worker concerns
Map field strengths to near background levels
Routine assessments encouraged

98. SMF Recommendations (cont.)
Area postings / brochures
Educate workers about anticipated interferences

99. SMF Conclusion Be aware of potential equipment effects below 0.5 mT
Equipment incompatibilities may result in personnel management difficulties

100. A Quick Recap… 5 types of non-ionizing radiation include:
Ultraviolet (UV) light
Visible light
Infrared (IR) light
Microwaves
Radiowaves

101. What is a Laser? A device that produces light
LASER stands for Light Amplification by Stimulated Emission of Radiation

102. Laser Applications Consumer Products Laser Pointers Laser Printers
                                
Laser Pointers
                  
Laser Printers
CD Players

103. Laser Applications
                                
Medical- eye surgery, therapy for Carpel Tunnel Syndrome
Industrial- welding, cutting

104. Light Basics Light travels in waves.
The electromagnetic spectrum is divided into sections based on wavelength.

105. What makes laser light different than conventional light?
Laser light has several unique qualities:
Monochromatic
Directional
Coherent
But what do these mean?

106. Monochromatic Light
Monochromatic light is light consisting of one wavelength only.
Monochromatic
Polychromatic

107. Directional Light Directional light has very low divergence.
Conventional light spreads in all directions, but laser light remains focused.
Directional
Non-Directional

108. Coherent Light
Coherent light consists of waves that are in phase with each other.

109. Lasing Material
Lasers contain a medium which is used to cause the monochromatic effect. There are several states of lasing medium
Solid State- Crystal injected “dopant”
Semiconductor- Diode laser
Liquid- dye laser
Gas- C02 laser

110. Laser Construction Lasing Medium (gas, liquid, solid, semiconductor)
Excitation Mechanism (power supply, flash lamp, laser)
Feedback Mechanism (mirrors)
Output coupler (semi-transparent mirror)

111. Laser Construction (con’t)

113. Laser Use Research Medical/Dental Study of mechanisms at interfaces
Detection of single molecules
Medical/Dental
Eye surgery

114. Laser Use (con’t) Commercial Industrial Supermarket checkout scanners
Determining site boundaries for construction
Industrial
Cutting
Welding

115. Laser Hazard Classification ANSI Z136.1-2000 Standard
Class 1 (Exempt)
Incapable of producing damaging radiation levels
Class 2 (Low power)
Eye protection is an aversion response
Visible ( nm)
CW upper limit is 1mW

116. Laser Hazard Classification ANSI Z136.1-2000 Standard (con’t)
Class 3 (Medium Power)
Divided into subclasses, 3a and 3b
Hazardous under direct or specular reflection
Non-hazardous under diffuse reflection
Normally non fire hazard
CW upper limit 0.5 W

117. Laser Hazard Classification ANSI Z136.1-2000 Standard (con’t)
Class 4 (High Power)
Hazardous to eye and skin from direct viewing/contact, specular, and diffuse reflections
Produce non-beam hazardous such as air contaminants
Fire hazard

118. Bio-Effects Primary sites of damage Laser beam damage can be eyes skin
thermal (heat)
acoustic
photochemical

119. Eye Bio-Effects Three different ways for eye exposure
Retina (visible and
IR-A)
Cornea (UV-B,
UV-C, IR-C)
Lens (UV-A)

120. Eye Bio-Effects (con’t)
Visible ( nm)
Possible damage to Retina

121. Eye Bio-Effects (con’t)
Near-ultraviolet ( nm)
Possible damage to Cornea

122. Eye Bio-Effects (con’t)
IR ( nm)
Possible damage to Lens

123. Skin Bio-Effects
Skin Sensitivity
Dermis (IR-A)
Epidermis (UV-B, UV-C)

124. How Often Do Accidents Occur?

125. General Laser Safety Wear appropriate protective eyewear
Use minimum power/energy required for project
Reduce laser output with shutters/attenuators, if possible
Terminate laser beam with beam trap
Use diffuse reflective screens, remote viewing systems, etc., during alignments, if possible
Remove unnecessary objects from vicinity of laser
Keep beam path away from eye level (sitting or standing)

126. Non-Beam Hazards Chemical Optical Fire Electrical
Chemical used in dye lasers can be known carcinogens or toxic also maybe difficult to dispose
Optical
Plasma radiation can be produced. Similar to welders flash
Fire
Class 3b and 4 lasers with high power outputs can cause fires
Electrical
Most common, very high incident in maintenance

127. Engineering Control Measures
Beam housings
Activation Warning System
Shutters
Beam Stop or Attenuator
Remote firing controls
Interlocks
Engineering controls are design features or devices that are applied to a laser or its environment for the purpose of reducing laser hazards. Engineering controls are considered to be the most effective types of control.
Examples are:
A list of required and recommended engineering control measures for each laser class is available in ANSI Z , Table 10

128. Administrative Control Measures
Class 3b and 4 Lasers
Warning signs/labels
SOPs
Training
Optical Paths Covered
Warning Logo
Information Label
Class 2 and 3a Lasers

129. PPE Control Measures
Gloves
Be wary of neck ties.
Special clothing
Of particular importance in prevention of laser hazards is eyewear. Laser protective eyewear is usually made of filters which absorb and/or reflect specific wavelengths of laser light.
An important factor to look for in choosing laser protective eyewear is the optical density (OD) of the lenses. The OD of the eyewear is a measure of its capacity to filter light; OD is the opposite of transmission. The higher the OD, the less the light that is transmitted to the eye. The OD must be chose so as not to impair vision significantly, yet at the same time, must be chosen so as to be capable of reducing the laser light to the MPE.
When choosing laser protective eyewear it is also important to select eyewear that is designed to protect against the wavelengths of the laser light that will be used. Eye wear designed to filter shorter wavelengths of light are not appropriate for use with lasers that emit longer wavelengths of light.
Laser protective eyewear cannot protect personnel if not worn.
Eyewear must be for the appropriate laser wavelength, attenuate the beam to safe levels.

130. Emergency Procedure Shut down the laser system
Provide for the safety of the personnel, I.e. first aid, CPR, etc.
If necessary, contact the fire department
Inform the Radiation Safety Division
Inform the Principal Investigator
DO NOT RESUME USE OF THE LASER SYSTEM WITHOUT APPROVAL OF THE LASER SAFETY OFFFICER

131. Irradiance E = Irradiance = W/cm2 Ф = total radiation power W A = area
a = beam diameter
r = viewing distance
Θ = beam divergence

132. Beam diameter D = a + r Θ a = beam diameter r = viewing distance
Θ = beam divergence

133. Optical Density Log (incident power / transmitted power)
OD = log (total H / TLV)