Injury & Disease Prevention

1. Part 2
Injury and Disease Prevention
Learning outcomes:
• Recognise the physical form of a substance to the
related health hazard
• Distinguish the relationship between the route of entry
into the body of a hazardous substance and associated
risks
• Distinguish between acute and chronic ill-health effects
• Acquire a basic understanding of exposure limits
• Apply a hierarchy of control measures to reduce the risk
of ill-health caused by exposure to chemical or biological
agents
• Outline the basic principles relating to the disposal of
waste and the control of atmospheric pollution.

2. Forms of Chemical Agents
A chemical may be in the form of :
1. A substance
A substance is a chemical element or a
compound, including any impurities.
2. A preparation
A preparation is a mixture of substances,
usually with a deliberately proportioned
composition.
(Note: Compounds are pure substances made of atoms of
two or more elements chemically combined in fixed
ratios e.g. H2O, CO2).

3. Forms of Chemical Agents
• Liquids (harmless to highly toxic corrosive acids and alkalis)
• Gases (formless chemical where its volume and state can be
changed by the combined effect of increased pressure and
decreased temperature)
• Vapours (gaseous form of a liquid below its boiling point)
• Mists (finely suspended droplets formed by condensation from a
gas or the atomising of a liquid or from aerosols/created by many
industrial processes e.g. car spraying)
• Fumes (fine particulate solids created by condensation from a
vapour e.g. metal in molten state have metallic fumes – oxides
produce highly toxic fumes)
• Dusts (solid particles of varying size/settle under gravity and
accumulate/airborne under turbulence of air movement)
• Aerosol (fine suspension of solid particles or droplets in a carrier
gas – the spray can).

4. Biological Agents and Hazards
Biological Agents will lead to biological
hazards. These hazards relate mainly to
illnesses contracted from exposure to
harmful micro-organisms.

5. Forms of Biological Agents
• Fungi (a fungus is a plant lacking chlorophyll
and reproducing by spores e.g. mushrooms,
moulds and yeasts)
• Bacteria (a bacterium is any of a large group of
single celled microscopic organism of various
shapes and sizes e.g. bacilli (rod shaped), cocci
(spherical), spirilla (spiral shaped) most of which
may cause disease.
• Virus – known as acellular organism and a
pathogenic agent, it multiplies rapidly inside a
living cell. It is unable to grow or reproduce
outside a host cell.

6. Main Classification of Substances
hazardous to Health
• Various hazard communication standards
are used in different countries
• Global Harmonisation of Systems for
Classification of Chemicals (GHS) –
United Nations backed.
• 2 basic “user groups” namely the actual
USER and the TRANSPORTER/hauler.

7. Categories of Danger (the RISKS)
associated with substances
• Physico-chemical effects caused by the
intrinsic physical or chemical properties of the
substance e.g. flammable, oxidising or explosive
• Health Effects – arising from a chemical
causing harmful effects to living organisms
(death, injury or adverse health effects) when
ingested, inhaled or absorbed. Toxic effects may
be acute or chronic e.g. cancer, local or
systemic, and reversible or irreversible
• Environmental effects – relate to the potential
of a chemical to damage one or more
environmental compartments i.e. air, soil, water
or groundwater.

8. Local Vs. Systemic
• A Local effect refers to an adverse health effect that
takes place at the point or area of contact. The site may
be skin, mucous membranes, the respiratory tract,
gastrointestinal system, eyes, etc. Absorption does not
necessarily occur. Examples: strong acids or alkalis.
• Systemic effect refers to an adverse health effect that
takes place at a location distant from the body's initial
point of contact and presupposes absorption has taken
place. Examples: arsenic effects to the blood, nervous
system, liver, kidneys and skin; benzene effects to the
bone marrow.
• Substances with systemic effects often have "target
organs" in which they accumulate and exert their toxic
effect.

9. Acute and Chronic Health Effects
• Acute - quantity of a toxic or harmful
substance absorbed into the body
produces harmful effects very quickly
(within seconds, minutes or hours)
• Chronic – harmful effects of a substance
absorbed into the body take a very long
time to appear (months or years)

10. Health Effects
• Toxic (e.g. potassium cyanide, carbon monoxide)
• Corrosive (e.g. Acids and Alkalis, Gases and Vapours)
• Irritant (e.g. dust, pollen, ultraviolet light)
• Sensitising ( substances or preparation causing allergic
reactions)
• Carcinogenic (cancer bearing substances and
preparation)
• Mutagenic (alter cell development and causes changes
in future generation)
• Toxic to Reproduction (“Reprotoxic” – affect male or
female fertility, harm caused to foetus or may cause
abnormal development of an embryo resulting in birth
defects ( substances called Teratogens)
(NOTE : Ref. the last 3 is collectively known as the “CMR”
effects).

11. Bacteria
• In human hosts, certain types of bacteria can
cause tetanus, pneumonia, syphilis, tuberculosis
and other illnesses. As long as the host is not
infected with antibiotic resistant bacteria, they
can be treated with antibiotics, which kill bacteria
or at least hamper their growth. Antiseptics,
sterilization and disinfectants can help prevent
contamination and risk of infection from bacteria.
• The term “friendly bacteria” is used to describe
the types of bacteria that offer some benefit. Not
only does bacteria help produce the food we eat
and keeps the soil fertile, it also helps us digest
our food. Bacteria in our digestive system help
to convert milk protein into lactic acid and inhibit
the growth of potentially harmful bacteria.

12. Legionella
• Legionella organisms are readily found in natural
aquatic bodies and some species have been
recovered from soil. The organisms can survive
in a wide range of conditions, including
temperatures of 0 to 63o C, pH of 5.0 to 8.5, and
dissolved oxygen concentrations of 0.2 to 15
ppm in water.
• Temperature is a critical determinant for
Legionella proliferation.
• The bacterium may be spread by aerosols from
contaminated water source. It affects the lungs
and is deposited in the aveoli and can be fatal.

13. Zoonoses
• A zoonosis (pronounced /zoʊəˈnoʊsɪs/) is any
infectious disease that is able to be transmitted
(by a vector) from other animals, both wild and
domestic, to humans or from humans to
animals.
e.g. ANTHRAX - caused by the bacterium Bacillus
anthracis which is highly lethal in some forms and
BRUCELLOSIS also known as undulant fever,
undulating fever, or Malta fever - primarily a disease of
domestic animals (goats, pigs, cattle, dogs, etc) and
humans and has a worldwide distribution, mostly now in
developing countries.

14. Bronchitis
• Bronchitis is an acute inflammation of the air
passages within the lungs. It occurs when the
trachea (windpipe) and the large and small
bronchi (airways) within the lungs become
inflamed because of infection or other causes.
• The thin mucous lining of these airways can
become irritated and swollen.
• The cells that make up this lining may leak fluids
in response to the inflammation.
• Coughing is a reflex that works to clear
secretions from the lungs.

15. Your Airways and Lungs

16. Pneumonia
• Pneumonia is an inflammation of the lung,
usually caused by an infection. Three
common causes are bacteria, viruses and
fungi. You can also get pneumonia by
accidentally inhaling a liquid or chemical.
• The best preventive measures include
washing your hands frequently, not
smoking, and wearing a mask when
cleaning dusty or moldy areas.

17. Addiction (to Tobacco)
• Addiction was a term used to describe a devotion,
attachment, dedication, inclination, etc. Nowadays, the
term addiction is used to describe a recurring
compulsion by an individual to engage in some specific
activity, despite harmful consequences to the individual's
health, mental state or social life.
• Tobacco smoke contains nicotine and harmane
(inhibitor), which combined give rise to addictive
stimulant and euphoriant properties. The effect of
nicotine in first time or irregular users is an increase in
alertness and memory, and mild euphoria.
• Nicotine also disturbs metabolism and suppresses
appetite. This is because nicotine, like many stimulants,
increases blood sugar levels.

18. Harmful Chemicals in Tobacco

21. ASTHMA
ASTHMA is a disease that affects the breathing passages of the
lungs (bronchioles). Asthma is caused by chronic (ongoing, long-term)
inflammation of these passages. This makes the breathing
passages, or airways, of the person with asthma highly sensitive to
various "triggers."
When the inflammation is "triggered" by any number of external and
internal factors, the passages swell and fill with mucus.
Muscles within the breathing passages contract (bronchospasm),
causing even further narrowing of the airways.
This narrowing makes it difficult for air to be breathed out (exhaled)
from the lungs.
This resistance to exhaling leads to the typical symptoms of an
asthma attack.
Because asthma causes resistance, or obstruction, to exhaled air, it
is called an obstructive lung disease. The medical term for such
lung conditions is Chronic Obstructive Pulmonary Disease or
COPD.

22. Virus
• A virus is basically a tiny bundle of genetic material - either DNA or
RNA- carried in a shell called the viral coat, or capsid, which is made
up of bits of protein called capsomeres. Some viruses have an
additional layer around this coat called an envelope.
• When viruses come into contact with host cells, they trigger the cells
to engulf them, or fuse themselves to the cell membrane so they can
release their DNA into the cell.
• Once inside a host cell, viruses take over its machinery to reproduce.
Viruses override the host cell’s normal functioning with their own set
of instructions that shut down production of host proteins and direct
the cell to produce viral proteins to make new virus particles.
• Viruses cause a number of diseases in eukaryotes. In humans, the
common cold, chickenpox, influenza, shingles, herpes, polio, rabies,
and AIDS (Acquired Immune Deficiency Syndrome) are examples of
viral diseases.
• Because viruses can transfer genetic material between different
species of host, they are extensively used in genetic engineering.

23. What is a VECTOR?

24. West Nile Virus
West Nile virus (or WNV) is a Virus of the
family Flaviviriades; part of the Japanese
encephalitis (JE) antigenic complex of
viruses. It is found in both tropical and
temperate regions. It mainly infects birds,
but is known to infect humans, horses,
dogs, cats, bats, chipmunks, skunks,
squirrels, and domestic rabbits. The main
route of human infection is through the
bite of an infected mosquito.

25. HIV and AIDS
• HIV stands for Human Immunodeficiency Virus.
HIV is a virus that takes over certain immune
system cells to make many copies of itself. HIV
causes slow but constant damage to the
immune system.
• AIDS stands for Acquired Immune Deficiency
Syndrome.
• AIDS is the condition diagnosed when there are
a group of related symptoms that are caused by
severe HIV infection. AIDS makes the body
vulnerable to life-threatening illnesses called
opportunistic infections.

26. How is HIV transmitted?
• HIV is transmitted through four (4) body fluids:
blood, semen, vaginal fluid, and breast milk.
In order to pass HIV from one person to another,
HIV-infected fluid from one person needs to get
into the bloodstream of another person.
• HIV is usually transmitted through sharing
needles, unprotected anal, vaginal, and
sometimes oral sex, and from mother to infant
before or during delivery or while breastfeeding.

27. AIDS
AIDS stands for Acquired Immune Deficiency Syndrome:
Acquired means you can get infected with it;
• Immune Deficiency means a weakness in the body's
system that fights diseases.
• Syndrome means a group of health problems that make
up a disease.
• AIDS is caused by a virus called HIV, the Human
Immunodeficiency Virus. If you get infected with HIV,
your body will try to fight the infection. It will make
"antibodies," special molecules to fight HIV.
• A blood test for HIV looks for these antibodies. If you
have them in your blood, it means that you have HIV
infection. People who have the HIV antibodies are called
"HIV-Positive."

28. How do you get AIDS?
Most people get the HIV virus by:
• having sex with an infected person
• sharing a needle (shooting drugs) with
someone who's infected
• being born when their mother is infected,
or drinking the breast milk of an infected
woman.

29. Opportunistic Infections (CDC/USA)
HIV disease becomes AIDS when your immune system is
seriously damaged. If you have less than 200 CD4 cells or
if your CD4 percentage is less than 14%, you have AIDS.
• PCP (Pneumocystis pneumonia), a lung infection;
• KS (Kaposi’s sarcoma) a skin cancer;
• CMV (Cytomegalovirus), an infection that usually affects
the eyes
• Candida, a fungal infection that can cause thrush (a
white film in your mouth) or infections in your throat or
vagina
AIDS-related diseases also includes serious weight loss,
brain tumors, and other health problems. Without
treatment, these opportunistic infections can kill you.

30. Is there a CURE for AIDS?
There is no cure for AIDS. There are drugs
that can slow down the HIV virus, and slow
down the damage to your immune system.
There is no way to "clear" the HIV out of
your body (as of today).

31. Routes of Entry into the Body
• Inhalation (inhaled substances e.g. dust Vs.
respirable substances e.g. vapours and
gases/depending on size of particles)
• Ingestion (entry through the mouth, to the
stomach and intestines/contaminated food and
drinks)
• Absorption (entry though the skin or via the
eyes)
• Aspiration (process whereby liquids or solids go
direct into the lungs other than by inhalation)
• Injection (entry into the body by high pressure
equipment or contaminated sharp objects).

32. The Epiglottis and Aspiration

33. Body Defences
Against Hazardous Substances
Natural defences include:
1. Airway Filtration (moist hair in the nose/the
sinuses/mucous tissue)
2. Lachrymation (tear production/eyelids/
eyebrows/secretion dilute irritants)
3. Immune Response (permeable epidermis/
sensitised lymphocytes-repeated
exposure/inflammation)
4. Inflammatory Response (defensive process but
can result in disease/reaction of tissue to a harmful
agent insufficient to kill the tissue/occurs when
foreign body enters the body by way of inhalation,
ingestion, absorption, pervasion, implantation,
surface penetration, trauma, energy
transformation).

34. Workplace Exposure Limits
(WELs)
• WELs provide the basis for controlling
airborne contaminants
• Ideally, “No Exposure” limit is the best
possible strategy
• If not reasonably practicable, it must
be adequately controlled (limitation of
the risk).

35. International Variations
• Occupational Exposure Limit (OEL) is
used in the UK
• Threshold Limit Value (TLV) is used in the
USA
• Indicative Limit Value (ILV) – EU countries
• Maximum Allowable Concentration (MAC).

36. Measuring Exposure in Units
• Parts per million (ppm)
• Milligrams per cubic metre of air (mg/m3 or
mgm3)
• Fibres per millimetre of air e.g. asbestos

37. Long Term and Short Term Limits
Depends on two (2) factors:
• the nature of the substance
• the length of the exposure

38. Long Term and Short Term
Exposure Limits
• Long Term Exposure Limit is the level of
airborne contaminant allowable over an
eight (8) hour period, used for substances
producing chronic effects
• Short Term Exposure Limit (15 minutes) is
the level of airborne contaminants
allowable over a 15 minute period, used
for substances producing acute effects.

39. Concentration Levels
It is expressed as time weighted averages
(TWA), meaning that measurements are
taken over the period in question and the
airborne concentration are then averaged
out.

40. Below is a graph of concentration over an
8-hour day at a hypothetical workplace.

41. Monitoring AIR QUALITY
• Sampling Techniques (location/method of
analysis/frequency of the sampling)
• Stain Tube Detectors (analysing gaseous
contamination of the workplace/types include
Draeger Multigas Detector, Automatic Multigas
Detector, Polytest Tubes and Toxicated Gas
Detectors)
• Passive Samplers (Dish type and Tube type to
sample concentration of airborne pollutants)
• Smoke Tubes (assess the strength and direction
of air flow)

42. Gas Detector

43. Passive Samplers (dish type with
absorbent material)

44. Limitations of Exposure Limits
• designed only to control the absorption into the body of
harmful substances following inhalation (not concerned
with absorption following ingestion or through control
with skin and eyes)
• take no account of human sensitivity or susceptibility
• take no account of the synergistic (or combined) effects
of mixtures of substances
• no sharp dividing line between “safe” and “dangerous”
conditions
• cannot be applied to working periods (shifts with
overtime) over the 8 hour period
• change in temperature, humidity or pressure may
increase the harmful potential of a substance.

45. Control Measures (Prevention)
The following hierarchy is widely accepted
when we address control measures:
• Eliminate the hazard
• Use physical or engineering controls which
reduce the risk at source
• Provide protection generally rather than
individually
• Control the risks to the person by job design,
management, or (as a last resort) personal
protective equipment.

46. Elimination or Substitution of
Hazardous Substances
Elimination
• requires careful examination of the work activity
and process
• appropriate risk assessment must be carried out
• replacement with materials which do the same
job but present no risk to health
• must understand the properties and behaviour of
alternative substances and material.

47. Elimination or Substitution of
Hazardous Substances
Substitution
If eliminating the risk is not practicable, the next
option is to reduce the risk by substituting the
hazard with a different one with less potential for
harm.
• using the same material but in a different physical
form (e.g. granulated pottery dlazes rather than
powders)
• Using a similar, but different substance altogether,
such as one with a lower volatility and/or higher
WEL.

48. Elimination or Substitution of
Hazardous Substances
Process Changes
• may demand changes in work methods
(e.g. vacuuming rather than sweeping)
Reduced Time Exposure
• two (2) methods to achieve i.e. provide
regular breaks and job rotation.
Enclosure and Segregation
• total enclosure or containment of the
hazard (using remote control robots)

49. Elimination or Substitution of
Hazardous Substances
Local Exhaust Ventilation (LEV)
• ideal to control dusts, vapours and fumes
generated from a point source
• some examples of LEVs are Fume
Cupboards (used in laboratories), Captor
hoods, Glove boxes and Receptor
hoods.

50. A Fume Cupboard

51. Fume Cupboard Extraction

52. Elimination or Substitution of
Hazardous Substances
Dilution Ventilation
• operates simply by diluting the contaminant
concentration in the general atmosphere to an
acceptable level (i.e. below the WEL) through
the usage of extracting fans
• two (2) important criteria have to be considered
i.e. the rate of contaminant generation and the
position of the extraction fan.

53. Elimination or Substitution of
Hazardous Substances
Respiratory Protective Equipment
• Respirators
• Breathing Apparatus
• Half Mask Respirator (single or twin cartridge)
• Full Face or Canister Respirator
(Note: Breathing Apparatus include Fresh air
hose apparatus, Compressed Airline
apparatus and Self-contained apparatus).

54. Elimination or Substitution of
Hazardous Substances
Other Protective Equipment and Clothing
• Gloves
• Overalls
• Eye Protection (spectacles, goggles, face
visors)

55. Basic Environmental Issues
There are three (3) broad classes of
pollution :
• Atmospheric pollution (fumes, smoke, dust
– the by-products of industrial processes)
• Water pollution (liquid wastes (effluent)
comprising toxic substances, etc)
• Land pollution (solid waste from industrial
processes deposited on land).

56. Control of Atmospheric Pollution
• Legislation and enforcement (checks on
emission limits)
• Permits from governing body e.g. DOSH
• Form of abatement technology (change-out,
scrubbers)

57. Other Forms of Control
• Government Legislation (prosecution)
• By-Laws (set by the local
council/compound)
• Education (personal hygiene/social
responsibility)
• Re-cycling (industrial wastes)

58. Disposal of Waste and Effluent
The hierarchy of waste management options
are :
• Waste reduction (process change and
optimizing process efficiency)
• Re-use e.g. glass bottles
• Recovery of waste (i.e. recycling/old
newspapers, old tires for rethreading,)
• Disposal (generally to landfill away from
dwelling settlement).

59. Air Quality Index
Air Quality Index
(AQI) Values Levels of Health Concern Colors
When the AQI is in this range: ..air quality conditions are: ...as symbolized by this color:
0-50 Good Green
51-100 Moderate Yellow
101-150 Unhealthy for Sensitive Groups Orange
151 to 200 Unhealthy Red
201 to 300 Very Unhealthy Purple
301 to 500 Hazardous Maroon

60. Do your part to help waste disposal

61. Part 3 – Injury
What is DPI?
Discomfort, pain and injury (DPI) covers
many conditions of the muscles and bones
which include:
• Gradual process injuries (GPI/work
related)
• Simple back pain (Back Injury)
• Strains and Sprains.

62. Contributory Factors and the
Combined Effects
There are many factors that work together, in varying
proportions to cause DPI.

63. Soft Tissue Injury
Soft tissue injury is damage of the soft tissue of
the body. These types of injuries are a major
source of pain and discomfort.
• The four fundamental tissues that are affected
are the muscles, ligaments, tendons and
nerves.
• Management of soft tissue injuries consists of
protecting the injured tissue; resting it with
splints, braces, or tape; ice; compression; and
elevation.

64. Common Causes of Soft Tissue Injury
• Soft tissue injury is caused by direct or indirect
trauma
• Direct trauma may happen in connection with
sports or other accidents, being struck by an
object or falling
• Indirect trauma commonly stems from overuse
of the tissue ( assembly line or factory workers
often suffer from this type because of the many
repetitive movements they have to do many
times a day).

65. Types of Soft Tissue Injury
Soft tissue injuries include ligament
sprains
(e.g. sprained ankle), tendon strains,
repetitive stress injury and carpal tunnel
syndrome.

67. Treatment Options
Treatment options might include:
• Physiotherapy exercises to promote
healing, strength and flexibility
• Electrotherapy
• Manual techniques such as mobilization
and massage.

68. The Healing Phases
In general, the injury will heal in phases:
• The first phase typically lasts 72 hours and is marked by
swelling, redness, warmth and pain.
• The second phase is the repair phase and lasts 48 hours
to six weeks. During this time, the body will create scar
tissue (collagen), and you may experience pain and/or
discomfort.
• The third is most important phase and is called the
remodeling phase because the collagen is remodeled to
replicate the damaged tissue. This phase will last three
weeks to one year or more.
• Severe injuries where the tissue has completely ruptured
require surgery to sew the torn pieces back together.

69. Spinal Cord Injury
• Spinal cord injury (also known as “myelopathy”
or SCI) is a life-altering injury to the spinal cord
that results in the loss of feeling and mobility.
• A “complete spinal cord injury” means that there
is no voluntary movement or physical sensation
below the injury. Both sides of the body are
affected equally.
• An “incomplete spinal cord injury” means that
some movement or sensation below the injury is
possible. Both sides of the body are not
necessarily affected equally.

70. Common Causes
Spinal Cord Injury
• The two most common causes of spinal
cord injury are trauma and diseases
• Trauma may be caused by slips and falls,
diving accidents, gun shot wounds or
other disruptions of the spinal cord
• Diseases such as polio, spina bifida and
tumors may also cause spinal cord injury.

71. Slip and Fall Injury
A "slip and fall" or "trip and fall" is the
generic term for an injury which occurs
when someone slips, trips or falls as a
result of a dangerous or hazardous
condition.

72. Burn Injuries
• Burn injuries result from a number of
different causes and can range from minor
to life threatening.
• A burn injury is defined as damage to the
skin or other organ from contact with heat,
radiation, electricity or chemicals.

73. Severity or Burn Depth
The severity of burn injuries are classified by the depth of
the burn in three different degrees: first, second, and third.
• First degree burns cause minor tissue damage only to
the outer skin layer. The burn is painful, leaving the skin
reddish and dry with little swelling.
• Second degree burns damage the first two layers of skin.
There is severe pain and blistering (bubbling). The skin is
moist, red, and swollen with minimal scarring.
• Third degree burns damage all layers of skin and may
also damage fat, muscle and bone tissue. The damaged
skin often is left depressed, charred, and leathery. Initially
there may be little pain due to the destruction of nerve
endings.

74. Causes of Burn Injury
• Burn injuries fall into four (4) categories with the most
common causes being, scalding hot and flammable
liquids and fires
• Thermal/contract burns – occur when the body comes into
contact with hot items, such as hot metals, scalding
liquids, steam and flames
• Radiation (ultraviolet) burns – are caused by prolonged
exposure to the ultraviolet rays of the sun (sunburns), as
well as tanning booths or beds
• Chemical burns – result from skin or eye contact with
strong acids (i.e., sulfuric acid) and bases, such as
alkaloids
• Electrical burns – result from the electrical current flowing
through the body
• Inhalation burns – result from breathing fumes or smoke
during a fire.

75. Skin Injuries - Blisters
Blisters are caused by injury, allergic reactions, or
infections, which may include the following:
• burns/scalds
• sunburns
• friction (from a shoe, for example)
• contact dermatitis (irritation or inflammation
caused by a foreign substance)
• impetigo (a contagious infection of the skin
caused by streptococcus bacteria)
• viral infections (including chickenpox and herpes
zoster)

76. Impetigo

77. Herpes Zoster
Herpes zoster, or shingles, is caused by
the same virus that causes chickenpox.
After an episode of chickenpox, the virus
becomes dormant in the body. Herpes
zoster occurs as a result of the virus re-emerging
after many years.

78. Herpes Zoster

79. Injury and Hearing Loss
An injury to the ear may cause temporary or permanent hearing loss.
You can be injured by a variety of forces, including:
• A blow, cut, or other trauma to the ear or ear canal. This may cause
bleeding and infection, which can result in temporary hearing loss. A
trauma may also damage the inner ear or cochlea, which can result in
permanent hearing loss.
• Strenuous coughing, sneezing, or nose-blowing, or a strenuous
bowel movement.
• A sudden, dramatic change in air pressure, such as occurs in scuba
diving or air travel. This may put too much stress on the eardrum or
other middle ear structures, resulting in bleeding or fluid imbalance in
the middle and inner ear. This type of injury is called barotrauma.
• A blow to the head. A blow may change the position (dislocation) of
the three bones of the middle ear (ossicle dislocation). A head injury
may also cause a ruptured eardrum (tympanic membrane
perforation).
• A sudden, extremely loud noise (such as an explosion, gunshot, or
firecracker). This is called acoustic trauma.

80. Hearing Loss
1. Conductive Hearing Loss e.g. vibrations, sudden
loud noise, abnormal bone growths, wax hardened
causing blockage.
2. Sensorineural Hearing Loss from head injury, birth
defects, high blood pressure.
3. Presbycusis due to ageing affecting the inner ear.
4. Noise-induced hearing loss (NIHL) - this is hearing
loss due to exposure to either a sudden, loud noise or
exposure to loud noises for a period of time. A
dangerous sound is anything that is 85 dB (sound
pressure level - SPL) or higher.
5. Drug induced - some medications can result in
damage to the auditory system with prolonged use.
They are called ototoxic.

81. The EAR

82. Eye Injuries
Eye injuries range from the very minor to severe
Injuries such as:
• Acids (such as sulfuric acid found in car
batteries) or alkalis (such as lye found in drain
cleaner and ammonia) can splash into your eyes
causing burning sensation
• Corneal abrasions (scratch)
• Light induced injuries
• Foreign bodies in the eye
• Subconjunctival Hemorrhage (rupture of blood
vessel).

83. Eye Diseases
• Cataracts (clouded lenses)
• Glaucoma (damage to the optic nerve
from too much pressure in the eye)
• Retinal Disorders (problems with the
nerve layer at the back of the eye)
• Conjunctivitis (a viral/bacterial infection
also known as pink eye)