Transcript physical agents.ppt

PHYSICAL
HAZARDS
H.R.Sarreshtahdar, MD
Physical hazards
 Heat
 Cold
 Vibration
 Radiation
 Atmospheric
pressure changes
HEAT
How does body get rid of heat?

Conduction

Convection

Radiation

Evaporation
Factors affect body temperature
o
Air temperature
o
o
Radiation
o
o
Air motion
o
o
Humidity
o
Type of clothing
o
Time exposed
o
Workload
Age/sex/race
Mass/weight
Health status
Diseases
Drugs
o
Acclimatization
status
WBGT index

The most important index of
workplace heat exposure

Calculation:
•
Air temp.
•
Air motion
•
Radiant heat
•
humidity
Heat Balance
Body response to heat

Peripheral vasodilatation

Sweating

Change in metabolic rate

Increased plasma & fluid volume
Occupational exposure to heat
 Outdoor
 Indoor
o
Farmers
o
Postage workers
o
Ranchers
o
Steel workers
o
Military personnel
o
Oven/Furnace
o
Fishers
o
Construction workers
o
Foundry
workers
workers
o
Glassblowers
Heat-related syndrome

Heat stroke

Heat exhaustion

Heat cramps

Heat syncope
Heat stroke

Signs and symptoms:
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
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
Cerebral dysfunction and altered mental status
Hyperpyrexia (core temperature → 41.1°C)
hot, dry skin (classic), or moist skin
(exertional)
Seizure, coma, tachycardia, hypotension
Laboratory:

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↑leukocytes, ↓ serum K, Ca, P, ↑ BUN, CPK,
ALT, AST
Concentrated urine with myoglobinuria,
pr.uria, tubular casts
Hyperuricemia, DIC, thrombocytopenia
Heat stroke

Treatment:
Rapid reduction of body temperature:
In the workplace:



Shady cool place
removing clothes
use evaporative cooling (The best method):
 spraying entire body with cool water,
blowing cool air to the body Or Use ice
packs, or water immersion
Prevention

Avoid reexposure to heat at least for 4 weeks

Work-rest regimens according to heat TLV

acclimatization

Engineering controls

Special suits

Shaded rest areas

Cool drinking water or electrolyte/carbohydrate
solutions
Heat exhaustion

Strenuous work in hot climates

Volume/electrolyte depletion

Core temperature > 38°C

Symptoms and signs:

Intense thirst, weakness, nausea, headache,
confusion, tachycardia, profuse sweating, moist skin

Important: may progress to heat stroke

Treatment: placing the patient in a cool and shaded
area, provide hydration and salt (oral or IV)
Heat cramp
Salt deficiency (replacement of sweat loss with
water)
 Symptoms and signs:
Painful muscle contractions, weakness, nausea,
vomiting
Moist and cool skin
Euthermia
Elevated CPK
Move the patient to a cool environment + balanced
salt solutions (4tsp salt per gallon of water)
1-3 days rest + salt supplementation

Heat syncope

Sudden unconsciousness after strenuous
work

Cutaneous vasodilation

Cool, moist skin

Hypotension
Treatment:
cooling and liquids
Prevention

Worker selection

Acclimatization

Work-rest cycles

Availability of cool places

Availability of cool drinks
COLD STRESS
IN THE WORKPLACE
Body reaction to cold environment

Increase heat generation


Shivering
Decrease heat loss

Vasoconstriction
Risk factors

Alcohol

Opium

CNS depresants

Alpha agonists & antagonists

Direct vasodilatator

Beta antagonists
Cold-induced diseases

Systemic

Local
Freezing

Frost bite
Non-freezing

Immersion foot
Systemic hypothermia
Body core T <35°C

Mild

Moderate

Severe
Treatment

Remove wet garments

Protect against heat loss

Maintain horizontal position

Avoid excess movements

Monitor core temperature

Monitor cardiac rhythm
Treatment

Pulse present:
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Adequate ventilation and O2 administration
Electrolyte and acid-base correction
Blood pressure correction
Rewarming:

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Passive rewarming
Active external rewarming (warm blankets, warm baths)
Active internal rewarming (blood, peritoneal dialysis,
heated air)
Pulse absent:


CPR until core T> 35
rewarming
Prevention

Wind chill index


Temperature
Wind velocity
Prevent core T from falling below 36°C
 Work-rest cycles according to WC index
and work intensity
 Suitable clothes
 Wind-protected, warm shelters
 Available hot food and drinks

Frostnip
Frostnip is the freezing of upper layers of
the skin.
Characterized by:
- white, waxy skin.
- general numbness
Frostnip is generally reversible and does no
major tissue damage.
Frostnip - treatment
Gently warm area by blowing warm air on it
or by placing it near a warm body part.
DO NOT rub the area! Rubbing can rupture
frozen cells, causing extensive damage.
•
Frostnip is a warning sign of possible
frostbite
Frostbite
Frostbite is a freezing of the surface and
deep layers of tissue.
Characterized by:
- white, and feels “woody”
- numbness, possible anesthesia
- deep frostbite can affect bone and
muscle
- purple/black color is from ruptured blood
vessels
Frostbite - treatment
Immerse affected area in 40-42 degrees C
water until thawing is complete.
- part will be extremely painful
Wrap affected part in sterile gauze
Affected part should not be used for
anything
- keep part from refreezing
Immersion Foot – trench foot
Immersion foot is caused by prolonged exposure of
the feet to wet, cool conditions.
Characterized by:
- yellowish, smelly feet
- possibly numb
- sloughing of skin tissue/itching
*Immersion foot may cause permanent damage to
foot tissues, leaving person susceptible to cold
injuries in future.
Immersion Foot - treatment
-
Careful washing and drying of feet.
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Keep feet dry as much as possible.
-
Keep off feet as much as possible until
healed.
VIBRATION
Types
 Whole-
body vibration
 Segmental
vibration
WBV

A kind of cummulative trauma

Jobs: drivers, miners, heavy equipment
operators

Frequency: 1 – 80 Hz (esp. below 20 Hz)

Two types: vertical (4-8Hz)
horizontal (1-2Hz)
Disorders
Musculoskeletal (LBP, Disk degeneration,
disk calcification, …)
 Neurological (decreased visual acuity,
Labyrinth disorders, insomnia,…)
 Circulatory
 Digestive
 Reproductive (abortion, congenital
malformation, …)

Prevention

↓ exposure duration

↓ unnecessary exposures

Isolation

Careful maintenance of machines

Resting after exposure
Segmental Vibration

Frequency: 5-5000 Hz (esp. 125-300 Hz)

Jobs: work with chain saw, grinder,
sander, pneumatic drill, jackhammer

Disorders: HAVS (Vibration-induced white
finger)
HAVS
A kind of secondary Raynaulds
phenomenon
 Signs and symptoms:
numbness and tingling → blanching →
cyanosis → atrophy → ulceration →
gangrene
Advanced disease: bone and cartilage
degeneration, joint stiffness, clumsiness

Treatment

Removing from more exposure

Massage, Shaking, Warm water

Nifedipine

PGE
Prevention

Better tool design

Anti-vibration gloves

HAV standards

Work practices

Medical surveillance

Work/rest cycles
Work practices

A/V gloves

Adequate clothing

Keep the hands warm

Avoidance from wetting the hands

Avoidance from smoking

Let the tool do the work

Maintain tools carefully
Types of radiation

Ionizing

Electromagnetic energy



Subatomic particles


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X-ray
Gamma ray
Electron
Proton
Α particle
Non-ionizing

Definition: energy in the form of
particles or waves

Types of radiation

Ionizing: removes electrons from atoms



Particulate (alphas and betas)
Waves (gamma and X-rays)
Non-ionizing (electromagnetic): can't
remove electrons from atoms

infrared, visible, microwaves, radar, radio
waves, lasers
Radiation wavelength in angstrom units
10
8
Radio
10-10
6
4
10
2
10
Infrared
10-8
10
V
i
s
i
b
l
e
10-6
Ultra-Violet
Light
1
-2
10
X-Rays
-4
10
-6
10
Cosmic Rays
Gamma Rays
10-4
10-2
1
102
Photon energy in million electron volts (MeV)
10
4