The document discusses various occupational hazards including physical, chemical, biological, and mechanical hazards. It provides details on specific physical hazards like noise, vibration, radiation and their resulting occupational diseases. Chemical hazards from metals, dusts, gases, and other chemicals are explained along with their effects. Biological hazards and prevention are briefly covered. Routes of exposure, types of occupational diseases, and anticipation of chemical hazards are also summarized.

1. Occupational Hygiene
Occupational Hazards
Lecture 11
Department of Public Health. ISM

2. OCCUPATIONAL HAZARDS
• Physical hazards
• Chemical hazards
• Biological hazards
• Mechanical hazards
• Psychosocial hazards

3. Primary irritants, Allergy,
Systemic toxicity
Gas, Vapour,
Aerosol, Dust,
Fume, Smoke, Mist,
Fog
Eating, Smoking
• Inhalation
• Ingestion
• Skin absorption
ROUTE OF EXPOSURE

4. FOUR TYPES
• Diseases only occupational in origin (pneumoconiosis)
• Where occupation as one of the causal factors
(bronchogenic carcinoma)
• Occupation as a contributory factor (chronic bronchitis)
• Occupation aggravating pre-existing condition (asthma)

5. PHYSICAL HAZARDS
• Dusts and Fibers
• Noise
• Corrosives
• Microclimate (Temperature, Humidity and Air velocity
Extremes)
• Ionizing Radiation
• Non-Ionizing Radiation (Illumination, glare, contrast, EMF)

6. OCCUPATIONAL DISEASES DUE TO PHYSICAL
AGENTS
• Heat - Heat stroke, Burns
• Cold - Frost bite
• Light - Miners Nystagmus, Cataract
• Pressure - Caisson disease, Air embolism

7. • Noise - NIHL, Hypertension, Irritability
• Vibration - Neuromuscular diseases, Peripheral
vascular diseases
• Radiation - Leukemia, Aplastic anaemia
• Mechanical - Injuries, Accidents
• Electricity - Electric shock, Burns
OCCUPATIONAL DISEASES DUE TO PHYSICAL
AGENTS

8. CHEMICAL HAZARDS
• Metals (lead, mercury, arsenic, cadmium, chromium,
zinc, beryllium, tin, silver, etc)
• Carbon compounds (organic solvents)
• Benzine, Toluene, Zylene
• Phenol, Nitrate, Napthalene, Isocyanates, Carbon
tetrachloride, Carbon disulphide, Vinyl chloride monomer,
etc
• Pesticides & toxic gases (ammonia phosgene, carbon
monoxide)

9. CHEMICAL HAZARDS
• Irritants
• Asphyxiants
• CNS Agents
• Specific organ agents
• Genetic activity
Acute versus Chronic

10. Irritants
• Respiratory
• Skin
• Eye
• Primary/Secondary
• Primary – at source of contact
• Secondary – travels through
blood to another area
• Reversible/Irreversible
• Sensitization
• Irritant that has a delayed
reaction on subsequent
exposure

11. ASPHYXIANTS
• Simple Asphyxiants
• N2
• CO2
• He
• CH4
• Dilute air so oxygen content
is low
• Chemical Asphyxiants
• CO
• HCN
• H2S
• Interact at cellular level to
inhibit oxygen uptake.

12. CENTRAL NERVOUS SYSTEM DEPRESSANTS
• Narcotics
• Anesthetics
• Depressants
• Aliphatic Hydrocarbons
• Increased chain length enhances
effect
• Addition of an alcohol group (i.e.
ethanol)
• Addition of a halide group
enhances the effect

13. SPECIFIC ORGAN ATTACK
• May be reversible or irreversible
• Blood - Hemotoxic
• Liver – Hepatotoxic
• Lungs – Pulmonotoxic
• Kidneys – Nephrotoxic
• Skin – Dermatotoxic
• Nerves & Brain - Neurotoxic

14. GENETIC ACTIVITY
• Typically is irreversible
• Causes cancer – Carcinogen
• Causes chromosome damage – Mutagen
• Causes birth defects – Teratogen
• Causes damage to reproductive system -Reproductive Hazard

15. • Gases - CO, CO2, HCN, H2S,CS2
• Dusts - Pneumoconiosis
• Metals - Lead, Mercury, Chromium,
Manganese
• Chemicals - Acids, Alkalines
• Solvents - Benzene, Trichloroethylene
OCCUPATIONAL DISEASES DUE TO CHEMICAL
AGENTS

16. ANTICIPATION OF CHEMICAL HAZARDS
• Consider the following:
• Raw materials
• Intermediates formed
• Final products
• Disposal of used products
• Maintenance materials
• “Cradle to Grave” thought process

17. ANTICIPATION OF CHEMICAL HAZARDS
• Occupational Safety and Health Administration (OSHA) has
established Permissible Exposure limits
• They are defined in time weighted average, TWA, for most working
conditions. Short Term Exposure Limits, STEL, for 15 minute
exposure. Ceiling, C, for maximum allowable concentration.
• Industrial Hygienists have established Threshold Limit
Values, TLV.

18. BIOLOGICAL HAZARDS
• Pathogenic organisms
• Five levels of classification
• 1 least dangerous
• 5 most dangerous
• Pathogenic organisms are typically not found in a chemical
processing facility
• Possible biological hazards in an industrial setting
• AIDS
• Hepatitis B

19. BIOLOGICAL HAZARDS
• Industries with possible biological hazards
• Pharmaceutical Manufacturing
• Food processing or agricultural products
• Typically, hazards are well contained

20. • Hepatitis B, Rabies, AIDS, Leptospirosis…,
• Occupational Cancers
• Cancer of Skin, Lungs, Bladder
• Occupational Dermatosis
• Dermatitis, Eczema
• Psychosocial Diseases
• Neurosis, Peptic ulcer, Hypertension
OCCUPATIONAL DISEASES DUE TO BIOLOGICAL
AGENTS

21. NEW PATHOLOGIES
• AIDS
• Stress
• Geriatrics
• Space Medicine
• Genetic Aberrations (longevity!)
• Cancer
• Robotics-related Injuries
• Migrant Global Workers
• Nanoparticles

22. DUSTS AND FIBERS
• Concerned about particle size and penetration into
pulmonary track
• D > 0.5 micron – does not reach lungs (but may ingest)
• 0.2 < D < 0.5 micron – respirable and gets stuck in lungs
• D < 0.2 micron – are exhaled

23. LUNG DISEASES CAUSED BY DUST
• Depends on chemical composition, particulate size,
concentration, shape, specific gravity & body’s
reaction
• Pneumoconiosis
• Asbestosis
• Silicosis
• Coal workers pneumoconiosis
• Lung diseases caused by dust of organic origin
• Byssinosis (exposure to cotton dust)
• Mushroom workers lung
• Suberrosis (Cork dust)
• Bird breeders lung (chickens, parrots, pigeons)
• Man made fibers
• Occupational asthma
• Flour insects and pollens: linseed, soya beans, teak wood,
hair, fur, etc: isocyanates, poly urethane, amines, metals

24. NOISE

25. DID YOU KNOW?
• About 30 million workers are exposed to hazardous noise on
the job
• Noise-induced hearing loss (NIHL) is the most common
occupational hazard for workers globally
• Hearing loss from noise is slow and painless; you can have a
disability before you notice it
• If you must raise your voice to speak with someone only 3 feet
away, you are in high (hazardous) noise.
• It is 100% preventable

26. Sound is a sensation of acoustic
waves, a disturbance that
propagates through a medium
having properties of inertia (mass)
and elasticity. The medium by which
the audible waves are transmitted is
air.
Basically sound propagation is
simply the molecular transfer of
motional energy. Hence it cannot
pass through vacuum. Speed of
sound 344 m/s
Frequency: Number of pressure cycles/time also
called pitch of sound (in Hz)
8e-3nm to 0.1mm
SOUND

27. THE HUMAN EAR
Outer Ear: Pinna and auditory canal concentrate
pressure on to drum
Middle Ear: Eardrum, Small Bones connecting
eardrum to inner ear
Inner Ear: Filled with liquid, cochlea with basilar
membrane respond to stimulus of eardrum with
the help of thousands of tiny, highly sensitive
hair cells, different portions responding different
frequencies of sound.
The movement of hair cells is conveyed as
sensation of sound to the brain through nerve
impulses
Masking takes place at the membrane; Higher
frequencies are masked by lower ones, degree
depends on freq.difference and relative
magnitudes of the two sounds

28. WHAT IS NOISE?
• Sound is a sensation of acoustic waves (disturbance/pressure
fluctuations setup in a medium)
• Noise is any unpleasant, unwanted, disturbing sound
• By-product of many industrial processes, e.g. operating
machinery
• Exposure to high levels of noise may lead to hearing loss and
other harmful health effects

30. HEARING LOSS
•Temporary Hearing Loss
- results from short term exposure to noise
- hearing returns when away from the noise
•Permanent Hearing Loss
- results from exposure to a moderate or high
level of noise over a long period of time
- hearing loss is PERMANENT
- Permanent damage or destruction of hair
cells in the ears
- Hearing cannot be restored

31. NOISE HAZARD RECOGNITION
• Need to shout
• Ringing sensation
• Degraded hearing after work
• Auditory testing

32. NOISE HAZARD
• Sound level measurement
L = 10 * Log (I/I0)2
L = Sound intensity, decibels (dB)
P = Sound pressure, rms (Pa)
I0 = Reference sound pressure, rms (20  Pa)

33. OSHA SOUND LEVEL PEL’S
Sound Level (dB) Exposure Time Limit (hr)
< 90 No Limit
90 8
95 4
100 2
105 1
110 ½
115 ¼
> 115 0

34. NOISE CONTROL
• ENCLOSE EQUIPMENT
• ENCLOSE OPERATOR
• SLOWER ROTATIONAL SPEED
• INTAKE/EXHAUST MUFFLERS
• PADDED MOUNTINGS

35. SELECTION OF HEARING PROTECTION DEVICES
• Hearing protection devices are selected according to:
• Employee comfort
• Level of noise exposure
• Noise Reduction Rate of device
• Type of work being performed
• Environmental conditions
• Employee may select hearing protection from a variety of
suitable hearing protectors provided by employer.

36. TYPES OF HEARING
PROTECTION DEVICES
• Ear muffs
• Foam insert
earplugs
• Semi-aural earplugs

37. EAR MUFFS
Advantages
• More protection at higher
frequencies than earplugs
• Various NRRs available
• Durable, long lasting
• Can be fitted on hard hat
• Reusable
Disadvantages
• Higher cost
• Eye glasses can interfere
with ear muff seal
• May be uncomfortable in hot
environments
• Must be cleaned before use
by another worker

38. FOAM INSERT EARPLUGS
Advantages
• More protection at lower
frequencies than muffs
• Various NRRs available
• Inexpensive; disposable
• Can be custom molded for
individual worker
• Reusable plugs are
available
Disadvantages
• Hands must be cleaned
before inserting earplugs
• Improper insertion
reduces NRR value

39. SEMI-AURAL CAPS
Advantages
• Various NRRs available
• Easy to insert
• May be used several times
• Ideal for people going in and
out of noisy areas
Disadvantages
• Improper insertion reduces
effectiveness
• More expensive than ear
plugs
• Typically have lower NRRs
than plugs or muffs

40. AUDIOMETRIC TESTING
• Monitors employee’s hearing over time
• Baseline audiogram must be performed within first 6 months of work
exposure ( 8 hour TWA ≥ 85 dBA)
• Annual audiograms are required each year after baseline audiogram
• Employer must pay for the cost of each required audiogram

41. VIBRATION
• Frequency
• Amplitude
• Acceleration

42. VIBRATION EXPOSURE
Contact with Vibrating Machine:
• Segmental Vibration
‘Segment of body’ such as hand-transmitted vibration (known as
hand-arm vibration or HAV)
• Whole Body Vibration
Vibration transmitted through the seat or feet (known as whole-
body vibration or WBV).

43. Industry Type of Vibration Common Source of Vibration
Agriculture Whole body Tractors
Construction Whole body
Hand-arm
Heavy equipment vehicles
Pneumatic tools, Jackhammers
Forestry Whole body
Hand-arm
Tractors
Chain saws
Furniture manufacture Hand-arm Pneumatic chisels
Machine tools Hand-arm Vibrating hand tools
Textile Hand-arm Sewing machines, Looms
Transportation Whole body Vehicles
Mining Whole body
Hand-arm
Vehicle operation
Rock drills

44. HAND ARM VIBRATION
• WHAT IS HAV?
HAV is vibration transmitted from work processes into workers’ hands
and arms. It can be caused by operating hand-held power tools such
as road breakers, hand-guided equipment such as lawn mowers, or by
holding materials being processed by machines such as pedestal
grinders.
• WHEN IS IT HAZARDOUS?
Regular and frequent exposure to high levels of vibration can lead to
permanent injury. This is most likely when contact with a vibrating tool
or process is a regular part of a person’s job.

45. HAND ARM VIBRATION
• WHICH JOBS AND INDUSTRIES ARE MOST LIKELY TO BE AFFECTED BY HAV?
Jobs requiring regular and frequent use of vibrating tools and equipment are
found in a wide range of industries, for example:
• Building and maintenance of roads and railways
• Concrete products
• Construction
• Forestry
• Foundries
• Heavy engineering
• Mines and quarries
• Plate and sheet metal fabrication
• Public services
• Public utilities

46. HAND ARM VIBRATION
WHAT SORT OF TOOLS AND EQUIPMENT CAN CAUSE VIBRATION INJURY?
• Chainsaws
• Concrete breakers/road drills
• Hammer drills
• Hand-held grinders
• Hand-held sanders
• Nut runners
• Pedestal grinders
• Power hammers and chisels
• Powered lawnmowers
• Riveting hammers and bolsters
• Strimmers/brush cutters
• Swaging machines.

47. HAND ARM VIBRATION
Moderate vibration High vibration
• impact wrenches
• carpet strippers
• chain saws
• percussive tools
• jack hammers
• scalers
• riveting or chipping hammers
• grinders
• sanders
• jig saws

48. HAND ARM VIBRATION - CAUSES & EFFECTS
WHAT INJURIES CAN HAV CAUSE?
Regular exposure to HAV can cause a range of
permanent injuries to hands and arms including
damage to the:
• Blood circulatory system (e.g. vibration white finger)
• Sensory nerves
• Muscles
• Bones
• Joints

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50. HAND ARM VIBRATION - CAUSES & EFFECTS
• HAV Symptoms
• Attacks of whitening (blanching) of one or more fingers
when exposed to cold/wet
• Tingling and loss of sensation in the fingers
• Loss of light touch
• Pain and cold sensations between periodic white finger
attacks
• Loss of grip strength
• Bone cysts in fingers and wrists
• Stockholm Classification

51. FACTORS THAT INFLUENCE THE EFFECT OF VIBRATION ON THE HAND
Physical Factors Biodynamic Factors Individual Factors
Acceleration of vibration Grip forces - how hard the worker grasps
the vibrating equipment
Operator's control of tool
Frequency of vibration Surface area, location, and mass of parts
of the hand in contact with the source of
vibration
Machine work rate
Duration of exposure each
workday Hardness of the material being contacted
by the hand-held tools, for example metal
in grinding and chipping
Skill and productivity
Years of employment
involving vibration exposure
Position of the hand and arm relative to
the body
Individual susceptibility to
vibration
State of tool maintenance
Texture of handle-soft and compliant
versus rigid material
Smoking and use of drugs.
Exposure to other physical
and chemical agents.
Protective practices and
equipment including gloves,
boots, work-rest periods.
Medical history of injury to fingers and
hands, particularly frostbite
Disease or prior injury to
the fingers or hands

52. HAND ARM VIBRATION - CAUSES & EFFECTS
) WHAT EFFECTS DO THESE INJURIES HAVE
ON PEOPLE?
• Painful finger blanching attacks (triggered by cold or wet
conditions)
• Loss of sense of touch and temperature
• Numbness and tingling
• Loss of grip strength
• Loss of manual dexterity
• Unable to work in cold/wet conditions
• Unable to do leisure activities such as fishing, golf,
swimming
• Need to avoid further exposure to vibration, or cold and
wet conditions
• Have difficulty handling tools and materials and with tasks
requiring fine finger manipulation

53. HAND ARM VIBRATION MANAGEMENT & CONTROL
• Identify those at risk from occupational vibration
• Assess the risk involved:
• The level, type and duration of exposure
• Any effects concerning the health and safety of workers at particularly sensitive
risk
• Any indirect effects from interactions between vibration and the workplace/other
work equipment
• Information provided by the manufacturers of work equipment
• The existence of replacement equipment
• Specific working conditions such as low temperatures
• Appropriate information obtained from health surveillance
• Prevent and/or control the risk

54. 54
WHAT CAN I DO TO CONTROL THE RISK?
• Look for alternative ways of working which eliminate the vibrating equipment altogether
• Make sure your employees use the most appropriate equipment for each job
• Minimize the time individuals use the equipment
• Break up periods of continuous equipment use by individuals
• Design the job so that poor posture is avoided.
• Construct jigs to hold materials or tools.
• Maintain tools to the manufacturer’s specifications to avoid worsening vibration for example:
o Replace vibration mounts before they are worn out;
o Ensure rotating parts are checked for balance and replace them if necessary;
o Keep tools sharp.
o Get advice from your trade association on best practice.
o Get advice from the equipment manufacturer on safe use of the equipment.
• Mechanize or automate the work or change the way of working
• Ask the manufacturer to add anti-vibration mounts to isolate the operator from the vibration source
• Provide tool support to take the weight of the tool allowing the operator to reduce grip and feed force
• Introduce a purchasing policy specifying low vibration performance for new equipment
HAND ARM VIBRATION MANAGEMENT & CONTROL

55. HAND ARM VIBRATION – MANAGEMENT & CONTROL
Workers can reduce the risk of hand-arm vibration syndrome (HAVS) by
following safe work practices:
• Employ a minimum hand grip consistent with safe operation of the tool
or process.
• Wear sufficient clothing, including gloves, to keep warm.
• Avoid continuous exposure by taking rest periods.
• Rest the tool on the work piece whenever practical.
• Refrain from using faulty tools.
• Maintain properly sharpened cutting tools.
• Consult a doctor at the first sign of vibration disease and ask about the
possibility of changing to a job with less exposure

56. Employee Information and Training
• Potential sources of hand-arm vibration
• The health effects of hand-arm vibration;
• Risk factors (e.g. high levels of vibration, daily length/regularity of exposure);
• How to recognize and report signs of injury;
• Ways to minimize risk, including:
• Changes to working practices to reduce vibration exposure;
• Correct selection, use and maintenance of equipment;
• How to use tools to reduce grip force, strain etc.;
• Maintenance of good blood circulation at work, e.g. by keeping warm,
exercising fingers and not smoking.
Employees should also have access to a proactive health surveillance program
HAND ARM VIBRATION MANAGEMENT & CONTROL

57. Employees should also have access to a proactive health surveillance
programme.
Regular Employees Checks:
• Have your fingers gone white on exposure to cold?
• Have you had any tingling or numbness in your fingers after using vibrating
equipment?
• Are you experiencing any problems with muscles or joints in your hands or arms?
• Do you have any difficulty picking up small objects such as screws or nails?
• Is it difficult to tell if something is hot or cold to the touch?
If the answer to any of these questions is ‘yes’, assume that there is a risk from
HAV to your employees.You should refer the employee to a doctor and take action
to reduce exposure.
HAND ARM VIBRATION MANAGEMENT & CONTROL

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OCCUPATIONAL VIBRATION
CONTROL STANDARDS
• National regulation
• For Hand Arm Vibration:
• The daily exposure limit value standardised to an eight-hour reference period shall be
5 m/s2.
• The daily exposure action value standardised to an eight-hour reference period shall
be 2,5 m/s2.

59. MICROCLIMATE AT WORK

60. Temperature Extremes
• Heat Stress
• Heat Stroke
• Heat Exhaustion
• Cold Stress
• Frostbite
• Hypothermia

61. Heat Stress
• Body’s Energy Balance
• Metabolic rate
• Radiation
• Convection
• Sweating
• External Conditions
• Temperature
• Humidity
• Air movement
• Radiation
In a typical healthy individual the internal core body
temperature may rise as much as 3°C during heat stress

62. Cold Stress
• Less Common in Industrial Situations
• Cold climates
• Refrigerated space
• Wind chill
• Responses to Cold Stress
• Body core temperature is typically 37°C
• Shivering when body Tc < 36°C
• Lose Consciousness at Tc < 34°C

63. Temperature Stress Control
• Hot Stress
• Air movement
• Periodic rest
• Remove to cooler location
• Cold Stress
• Limit exposure time
• Protective clothing

64. ELEMENTS OF OCCUPATIONAL HEALTH SERVICES
• Medical treatment
• Assessment and control of work environment
• General preventive health measures
• Preventive medical examinations

65. PREVENTION OF OCCUPATIONAL HEALTH
HAZARDS
• Administrative Measures
• Engineering Measures
• Ergonomics
• Medical Measures

66. MEDICAL MEASURES
• Pre-employment medical check up
• Periodic medical examination
• Health promotion
• Health education
• Specific protection
• Assessment of risk by supervision of working environment

67. PRE-EMPLOYMENT MEDICAL EXAMINATION
• To determine the physical and emotional capacity of
the individual to perform the job.
• To provide base line health data for epidemiological
and legal purposes.
• To counsel the person for correction of diseases /
habits which may harm later.
• Assessment of pre-existing toxicity / impairment due to
past exposure, if any.

68. PRE-PLACEMENT MEDICAL EXAMINATION
HAZARD UNDESIRABLE CONDITIONS
Lead Anaemia, Hypertension, Peptic
ulcer
Dyes Asthma, Skin & Kidney disease
Solvents Liver & Kidney disease,
Alcoholism
Silica Tuberculosis, Chronic lung
disease
X rays / Radium Blood diseases

69. PERIODIC MEDICAL EXAMINATION
• Evaluation of general health status.
• Earliest detection and prevention of work related
disorders.
• Early detection, control and prevention of any health
disorder which may affect the ability to perform the job.
• To detect deviation in health status from base line data.
• Detection of infectious / communicable diseases which
may affect others.