Transcript IONIZING RADIATION - Calcupa

Physical Hazards
Noise, Radiation, and
Ergonomics
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NOISE AND ITS EFFECT ON
HEARING
Introduction
• Definitions
• Biological Process of Hearing
• Two Types of Hearing Loss
– Conductive Hearing Loss
– Sensory Hearing Loss
• Regulatory Levels
• Audiometric Testing
• Measuring Noise
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Definitions
• Sound:
– Composed of Frequency and Intensity
• Frequency or pitch:
– Hertz (Hz)
• Intensity or loudness:
– Decibels (dBA)
• A doubling of the level of sound is
perceived as less than double
– Do not trust your ears
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Biological Process of Hearing
• Outer ear collects sound
energy (pressure waves)
• Sound travels down the
ear canal to the eardrum
• Sound waves set the
eardrum in motion
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Biological Processes of Hearing
• Inside the cochlea, hair cells
bend as waves pass by sending
pulses via the auditory nerve to
the brain.
• Sound energy is converted from
mechanical vibrations to fluid
waves to electrical pulses.
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Two Types of Hearing Loss
• Conductive
• Sensory
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Conductive Hearing Loss
• Caused by damage to or a malfunction of
the outer and middle ear
• Some causes
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excessive ear wax
fluid in the ear
a torn eardrum
Colds
• Usually hearing is restored once the cause is
diagnosed and treated
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Sensory Hearing Loss
• Caused by damage to or a
malfunction of the inner ear,
auditory nerve, or the brain
• Causes of sensory hearing
loss
– Aging, Damage to fetus,
Hereditary, Noise, Disease,
Injury, Drugs
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Sensory Hearing Loss
• Cannot be corrected medically or surgically
• Hearing loss in the workplace is typically a
sensory hearing loss
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Regulatory Levels
• Continuous noise
– 85 dBA, 8 hour TWA - Action Level
• hearing conservation program
• training
• medical monitoring
– 90 dBA, 8 hour TWA - Permissible Exposure
Level (PEL)
• Wear Ear Plugs
• Impact noise- no exposures above 140 dB
shall be permitted
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Audiometric Testing
• Audiogram
– Measures how loud a sound has to be before
you can hear it
– Comparing current to previous audiograms
• Shows if hearing loss has occurred and at which
frequencies
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Measuring Noise
• Sound Level Meter - Instant reading
– grab sample
– Quest 215
• Dosimeter - TWA
– noise exposure is integrated over time
– Quest 7 B
– Du Pont MK 1, 2, 3
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Types of Hearing Protection
Devices
• Foam earplugs
• Earmuffs
• Noise Reduction
Rating ( NRR )
– Plugs + Muffs
• Take the higher NRR
and add 5 dB to it
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NRR - Noise Reduction Rating
• NRR and choosing an ear plug:
Earmuff’s NRR - Subtract 25%
Foam/expanding ear plugs - Subtract 50%
All other plugs - Subtract 75%
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Earplugs
• Advantages:
– small and lightweight
– comfortable in hot environments
– easily used with other safety equipment
• Disadvantages:
– may become loose and require occasional
refitting
– frequently soiled
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Earmuffs
• Advantages:
– fits better for longer periods of time
• Disadvantages:
– may fit tight on your head
– uncomfortable in warm environments
– effectiveness is limited to the quality of the seal
around your ear
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Inserting foam earplugs
properly:
• Reach around back of your head
• Gently pull your ear back and
up
• Roll the plug into a small
diameter
• Insert the plug well into the ear
canal
• Hold the plug in place for a few
seconds while it expands and
forms a good seal
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Hearing Protection
• Make sure that the earmuffs fit snugly
around your ears
• Use earplugs if you wear glasses, earrings,
or have facial hair which prevent the
earmuffs from forming a good seal
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Caring for Hearing Protection
Devices
• Foam Earplugs:
– store them in a clean, cool, dry place
– if earplugs become soiled, torn, or stiff, discard
them and get a new pair
• Earmuffs:
– store them in a clean, cool, dry place
– inspect your earmuffs for cracks around the
foam cups.
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IONIZING RADIATION
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OBJECTIVES
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Ionizing Radiation Characteristics
Radiological Response
Biological Consequences / Health Effects
Regulations/Standards
Radiation Protection/Controls
Instrumentation
Types of radiation
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IONIZING RADIATION
DEFINITIONS
• Ionizing Radiation (IR) - Any particles or rays
given off (radiate) from a source that produces
ionization
• Ionization - When atoms or molecules become
charged - unbalanced electron proton ratio.
• Radiation - Refers to the way particles & rays
radiate from their source at speeds up to that of
light.
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RADIOLOGICAL RESPONSE
• Spills of Radioactive Material
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Stop the spill,
Warn others of the spill,
Isolate the area and
Minimize exposure to radiation
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IONIZING RADIATION
CHARACTERISTICS
• Common Types of IR
– Alpha
– Beta
– Gamma
– X-rays
• Types of Non-IR
– Radiowaves & Microwaves
– Infrared Light
– Visible Light
– Ultrasound
– UV Light
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IONIZING RADIATION
CHARACTERISTICS
• Alpha Radiation ()
– Physical Characteristics (Helium w/o electrons)
– Weak penetrating power
• Cannot penetrate a sheet of paper
– Internal Hazards
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IONIZING RADIATION
CHARACTERISTICS
• Beta Radiation ()
– Physical Characteristics (electron)
– External Exposure
• Skin Damage = “Beta burn”
– Method of Ionization
– Annihilation Radiation
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IONIZING RADIATION
CHARACTERISTICS
• Gamma Radiation ()
– Indirectly ionizing radiation (electromagnetic
ray - e.g. light)
– Energy bundles - have no charge or mass
– Travels much farther than  or  radiation
– Can pass through a body without hitting
anything or give an atom all or part of its
energy.
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IONIZING RADIATION
CHARACTERISTICS
• Units
– Rad: Absorbed dose equal to 0.01 Joule/kg in
any substance.
– Rem: Conventional unit for dose equivalent.
• The dose equivalent in rem is equal to the absorbed
dose in rad multiplied by the quality factor.
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IONIZING RADIATION
CHARACTERISTICS
• Radiation dose is expressed in rads
• For  and  radiation, 1 rad = 1 rem
• For  radiation, 1 rad = 20 rem
Rem = (Rad)(QF)
Quality Factor (QF) for:  and  = 1
=20
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SOURCES OF EXPOSURE
• Natural Sources (81%)
– 55% - Radon
– 8% - Cosmic
– 8% - Terrestrial (coal, crude oil & natural gas,
phosphate rock products, sand, hot springs &
caves)
– 10% - Food & Water (i.e., Potassium-40)
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SOURCES OF EXPOSURE
• Man-made Sources (19%)
– 11% - Medical X-ray (-rays)
– 4% - Nuclear Medical Exposures
– 3% - Consumer Products
– <1% - Other Sources (occupational sources,
nuclear fallout, nuclear fall cycle radioactive
waste, hospital radioactive waste, radioactively
contaminated sites, etc.)
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SOURCES OF EXPOSURE
• For the U.S. population, average annual total
effective dose (natural & anthropogenic) is
approximately 360 mrem (0.360 rem).
• For the general public, the exposure limit is 0.1
rem/year or 2 mrem/hr.
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BIOLOGICAL CONSEQUENCES /
HEALTH EFFECTS
• DNA is the primary target
• Radiation can produce free radicals elsewhere in the body
that then reacts with DNA
• DNA damage is cumulative
• Cells are most sensitive to radiation damage if
– Have a high mitotic (cell division) rate
– A slow (long) mitotic cycle
– Undifferentiated stem cells
• Exposure to the eyes causes cataract formation.
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BIOLOGICAL CONSEQUENCES /
HEALTH EFFECTS
• Acute Effects: Acute Radiation Syndrome
(ARS)
– Only seen after whole-body exposures above
100 rad
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REGULATIONS/STANDARDS
• Worker Limits - Adults Only:
– Radiation workers (Fed & State) =
5 rem/year
– Total Effective Dose = 5 rem/year
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TYPES OF RADIATION
Alpha
– U-238, Pu-238, Pu-239, Ra-226, Po-210, Am241
• Beta
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H-3, C-14, S-35, Pu-241 (low-energy)
P-32, Sr-90, I-131 (medium to high energy)
Also includes partial gamma (I-131)
Other Gamma (Cs-137, Co-60, Ir-192
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RADIATION
PROTECTION/CONTROLS
• Time:
– Exposure increases linearly with an increase in
the amount of time spent.
– Reduce the time of exposure to a minimum
– ALARA (as low as reasonably achievable)
• Shielding:
– Lead and concrete - absorbs the radiation.
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RADIATION
PROTECTION/CONTROLS
• Distance:
– Dose rate is inversely proportional to the distance
squared from the source.
I1 = I2(D2/D1)2
where: I1 = is the intensity at a distance D1, and
I2 = is the intensity at a distance D2
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RADIATION
PROTECTION/CONTROLS
• PPE:
– Prevent contamination of particles on the surface of the
skin
– The use of shield layers such as eye shield and gloves prevents particles from depositing on the body and
shields by absorption.
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INSTRUMENTATION
Example:
Ludlum 3
(, , and )
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INSTRUMENTATION
Example:
Ludlum 19
( and x-ray)
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INSTRUMENTATION
Example:
SAIC Dosimeters ()
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REGULATORY AGENCIES
• California Dept. of Health Services, Radiation Branch:
State Regulatory
• Nuclear Regulatory Commission (NRC)
– Regulates nuclear power plant operations
– Regulates the use of radioactive material in research and
medical applications
– NRC regulations apply to all types of ionizing radiation (IR)
– Sets limits on the total dose of IR above background
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Ergonomics
• A quick overview
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Ergonomics
• The study of interactions between humans and
their working environment
• Repetitive motion is one branch
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Ergonomics
• Examples:
– Carpal tunnel syndrome - compressed median nerve
due to swelling of the tendon sheath
• Prolonged flexing of the wrist - typing
– Tendentious - inflamed tendons due to stress
• Excess motion or stress - frayed, bumpy thick tendon
– White Finger - loss of adequate blood supply to fingers
• Vibrations, very tight gripping - Jack hammer
– Lower back pain - back stresses especially poor lifting
• Bent back, twisting motion, excess weight
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Ergonomics
• Lifting, protect the back!
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Keep back straight
Forced to lift with legs
Exponential increases with “leaning over” to pick up
Pivot point, lower back
Think, do not use jerky rapid motion
Do not twist
Do not raise above shoulders
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Ergonomics
• Tools, protect the hand (wrist)
– Keep writs straight with respect to the arm, no bending
– Encircled tool should not allow fingers to touch palm
– Vary tasks, avoid doing something repetitively without
breaks
– Keep shoulder relaxed and elbow at the side of the
body
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Ergonomics
• Universal Key Points
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Avoid sustained repetitive motions
Flex joints minimally
Work between shoulder and elbow height
Use good illumination
Do only what is comfortable, not pushing to the limits
Use good posture
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QUESTIONS?
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