Transcript Chapter 1

Physical Agents
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Physical Agents
Noise
 Just because we cannot hear
the sound does not mean that it
is not present and possibly
causing hearing damage
 Human hearing response is
conditional on three
characteristics:
 Frequency
 Duration
 Loudness
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Types of Hearing Loss
 There are two main types of hearing loss:
 Conductive : caused by trauma, or
infection
 Sensorineural: sometimes referred to as
nerve deafness and is almost always
irreversible.
 Noise affects humans in three ways:
 Physiologically
 Sociologically
 Psychologically
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Sensorineural
 usually affects frequencies in the
speech range approx. 500 – 3000
Hz causing ringing in the ears
 Affects the cochlea and is almost
always irreversible
 It is not uncommon for hearing
loss to occur gradually over five to
ten years.
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Sociological
• Can have cardiovascular,
neurological and biological
changes
• Other side effects can include:
– Vasoconstriction (vein
constriction)
– Hyper-reflexia,
– Disturbances in equilibrium
and vision.
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Psychological
 noises may be well below acceptable
standards, but they tend to be irritating
to some (e.g. Tap dripping)
• Psychological effects from exposure to
noise can make personal conversation
and participation in large crowds to be
difficult and uncomfortable.
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Noise Exposure Standards
 In British Columbia, the noise
standard or threshold limit value
(TLV) allowed for 8 hours is 85
dB(A)
 Diesel truck at 20 meters
 Ontario and Quebec – 90 dB(A)

does this make central Canada nosier?
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Noise Control
 The first strategy used to reduce noise
is to make the Source quieter
 This can be accomplished by:
 Adding sound-absorbing materials
 Placing vibrating pads under
machinery
 Isolating the equipment,
 Purchasing a new machine.
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Noise Control
 The second strategy (Path) involves
moving the worker away from the
source or erecting sound barriers
between the worker and the noise
 The third strategy (Human) involves
the use of personal protective
equipment (PPE). Though not always
the best method, it is the most
commonly used method.
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Vibration
 Vibration –the oscillating motion of a
particle or body moving about a
reference position
 Vibration is a health hazard for 3
reasons:
 It can cause whole body vibration
(e.g. driving)
 Particular parts of the body may be
affected (segmental vibration)
 Vibration may cause “resonance”
which may cause severe reactions
to a particular frequency
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Vibration
• The health effects of whole body
vibration include
– inhibition of muscular reflexes,
– impaired or blurred vision
– alterations of brain electrical
activity.
• Raynaud’s Phenomenon – (white
fingers) is caused by restricted blood
circulation in the fingers.
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Thermal Stress
• Are conditions that involve cold and hot
temperature extremes, usually coupled
with high or low humidity
• When referring to heat, there are three
methods of heat transfer:
• Conduction – contact between two
surfaces,
• Convection – heat added to
surroundings
• Radiation – energy through
electromagnetic waves.
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Radiation
•
Radiation is divided into
two groups:
•
Ionizing
•
short wavelengths
•
Non-ionizing
•
long wavelengths
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Ionizing Radiation
• Ionizing Radiation – is any form of
electromagnetic energy (I.e. X-Rays,
gamma rays, or alpha particles
• Control of exposure will include:
regular monitoring, shielding,
protective equipment, and extensive
training
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Non-Ionizing Radiation
• Non-ionizing radiation – refers to
electromagnetic radiation that does not
have energies great enough to ionize
matter.
• Types of non-ionizing radiation include:
• Ultraviolet light
• Visible (white light) radiation
• Infrared radiation
• Microwave radiation
• Radio waves
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Exercise B Physical agents in the workplace

Using as examples, two (2) common forms of recreation and
entertainment settings (e.g. restaurants, pubs, theatres, malls, sports
venues)
(a) What physical agents are present in these settings? Identify five
(5) agents each, using the chart below as a guide. Be specific.
(b) What risks (consequences) do they pose for:
- Customers?
- Employees?
(c) What “Source - Path - Person” controls can be used to reduce or
eliminate the effect(s) of the physical agents?
Agent
Exposure
Control
Noise
Ambient
Source
Vibration
Acute
Path
Thermal stress
Chronic
Person
Radiation
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