13 Physical and Psychological Health Hazards and Risk Controls

Question 1

Effects of exposure to noise

Answer 1

Physical effects include:

• Temporary reduction in hearing sensitivity as a result of short duration exposure to excessively loud noise.
• Temporary ringing in the ears as a result of short duration exposure to excessively loud noise.
• Noise-induced hearing loss (NIHL) – permanent loss of hearing as a result of repeated exposure to excessively loud noise.
• Tinnitus – persistent ringing in the ears as a result of repeated exposure to excessively loud noise.
• Inability to hear the following as a result of background noise:
  
  • Hazards such as vehicles.
  • Alarms and warning sirens.
  • Conversation and spoken instructions.

Psychological effects include:

• Stress – caused by irritating nuisance/background noise.
• Difficulty concentrating and an increase in errors – caused by nuisance/background noise.

Question 2

How the hearing mechanism itself is damaged

Answer 2

The hearing mechanism transmits noise from the outside environment through the outer and middle ear to the inner ear (the transmission route is ear canal; eardrum; hammer; anvil; stirrup; cochlea).

Microscopically small sensory hairs in the inner ear then detect the noise and send nerve impulses to the brain. Exposure to excessively loud noise disturbs these microscopically small hairs. One-off exposures to high noise levels (e.g. four hours of work in a high-noise area) will probably cause a temporary loss of hearing sensitivity (called ‘temporary threshold shift’) and temporary ringing in the ears (tinnitus). The microscopically small hairs will have been disturbed, but not damaged beyond repair. Repeated exposures result in permanent threshold shift – irreparable damage – because the sensory hairs are parts of nerve cells that do not regenerate. This is noise-induced hearing loss

Question 3

Typical dB levels associated with different noise sources

Answer 3

Measurement in dB(A) Sound

0 The faintest audible sounds

20-30 Quiet library

50-60 Conversation

65-75 Loud radio

90-100 Power drill

140 Jet aircraft taking off 25m Away

Question 4

Different types of noise meters

Answer 4

• Simple sound level meters
• Integrating sound level meters
• Dosimeters

Question 5

Noise exposure limits

Answer 5

• Lower Exposure Action Value = 80 dB(A) Daily Personal Noise Exposure At this value, the employer must:
  
  • Carry out a noise assessment.
  • Provide information, instruction and training to employees.
  • Make hearing protection available.
• Upper Exposure Action Value = 85 dB(A) Daily Personal Noise Exposure At this value, the employer must:
  
  • Carry out a noise assessment.
  • Reduce noise exposure to the lowest level reasonably practicable.
• If noise levels are still above 85 dB(A) the employer must:
  
  • Establish mandatory hearing protection zones.
  • Provide information, instruction and training to employees.
  • Provide hearing protection and enforce its use.
  • Provide health surveillance.

Question 6

Basic Noise Control Measures

Answer 6

• Reduce Noise at the source
• Substituting the Source
• Maintenance
• Damping
• Modifying the Process
• Silencing
• Interrupt the pathway
  
  • Insulating
  • Isolation
  • Absorption
• Protecting the receiver
  
  • Acoustic Havens
  • Hearing Protection

Question 7

Advantages and disadvantages of Ear defenders or Muffs

Answer 7

Easy to supervise and enforce use as they are visible Less chance of ear infections Higher level of protection possible through all sound frequencies; bone transmission is reduced Can be integrated with other PPE, e.g. hard hats Re-usable Uncomfortable when worn for long time Must be routinely inspected, cleaned and maintained Efficiency may be reduced by long hair, spectacles or earrings Incompatible with some other items worn (e.g.spectacles) Need dedicated storage facility

Question 8

Advantages and disadvantages of Ear plugs

Answer 8

Cheap and easy to use Disposable Available in a range of types and designs Often more comfortable to wear Do not interfere with any other items worn (e.g.PPE) Difficult to see when fitted, so supervision and enforcement difficult Risk of infection if dirty or if cross-contaminated when inserted Need to be correctly sized to fit the individual Effectiveness decreases with usage Interfere with communication

Question 9

Effects of exposure to Vibration

Answer 9

Hand-Arm Vibration Syndrome (HAVS) • Vibration white finger (VWF) • Nerve damage • Muscle weakening • Joint damage Whole-Body Vibration Effects

Question 10

Vibration Exposure Limits

Answer 10

Daily Exposure Action Value = 2.5m.s-2 hand-arm vibration / 0.5m.s-2 whole-body vibration At this value, the employer must: –– Carry out a vibration assessment. –– Reduce vibration exposure to the lowest level reasonably practicable. –– Provide information, instruction and training to employees. –– Carry out health surveillance. Daily Exposure Limit Value = 5.0m.s-2 hand-arm vibration / 1.15m.s-2 whole-body vibration At this value, the employer must: –– Carry out a vibration assessment. –– Immediately reduce exposure below the exposure limit value (ELV ).

Question 11

Basic Vibration Control Measures

Answer 11

Reduce the vibration at source • Eliminate the source • Substitute the source • Change work techniques • Maintenance Interrupt the path from source to receiver • Isolation Limit the duration of exposure

Question 12

Types of Ionizing Radiation (5)

Answer 12

Alpha particles Beta particles X-Rays Gamma-rays Neutrons

Question 13

Effects of exposure to Ionizing Radiation (2/8-3)

Answer 13

Acute effects of exposure to high doses of ionizing radiation include: • Radiation sickness - nausea, vomiting and diarrhea. • Blistering and ulceration of the skin. • Hair loss. • Dermatitis. • Cataracts. • Anemia, due to red blood cell damage. • Reduced immune system, due to white blood cell damage. • Infertility. Chronic effects • Cancer. • Genetic mutations. • Birth defects

Question 14

Types of non-ionizing Radiation

Answer 14

• Ultra-violet (UV) – high-frequency electromagnetic radiation (light) emitted by white-hot materials such as the arc produced during arc-welding or excessive exposure to the sun. Health effects include redness and burns to the skin (e.g. sunburn); pain and inflammation to the surface of the eye leading to temporary blindness known as photokeratitis (often called arc-eye or snow-blindness); increased risk of skin cancer; premature aging of the skin. • Visible light – electromagnetic radiation between the UV and IR frequencies that is visible to the human eye, arising from artificial lighting and display screens. Visible light is particularly dangerous to the eyes (because the retina is very sensitive to it). It can cause temporary blindness if it is intense (disability glare) and permanent eye damage if it is very intense (e.g. from a high-powered laser). • Infra-red (IR) – lower frequency electromagnetic radiation (light) emitted by red hot materials such as molten metal being poured into castings. Health effects include redness and burns to the skin; retinal burns, development of eye cataracts over time. • Microwaves – lower frequency electromagnetic radiation emitted by a microwave generator. (Note that microwaves can be categorised as a subset of radiowaves.) Microwaves are absorbed and cause internal heating of the skin. High doses cause internal organ damage and can be fatal. • Radiowaves – lower frequency electromagnetic radiation emitted by an antenna. Radiowaves are absorbed and cause internal heating in the same way as microwaves.

Question 15

Types of Radiation

Answer 15

Ionization Radiation Non-Ionization Radiation Radon Gas

Question 16

Sources of Ionizing Radiation (5)

Answer 16

–– Alpha particles – smoke detectors and science labs. –– Beta particles – science labs and thickness gauges. –– X-rays – medical radiography and baggage security scanners. –– Gamma-rays – industrial radiography. –– Neutrons – nuclear power stations.

Question 17

Sources of Non-ionizing Radiation (5)

Answer 17

–– UV – sunlight; arc-welding. –– IR – red-hot steel in a rolling mill; glass manufacture. –– Visible light – laser levelling device; laser pointer. –– Microwaves – industrial microwave oven in a food factory; telecommunications equipment (e.g. a mobile phone antenna). –– Radiowaves – radio, TV or radar antennae.

Question 18

Sources of Radon (3)

Answer 18

–– Geological tasks, e.g. in mining and quarries. –– Construction and demolition of properties. –– Farming and outdoor work

Question 19

Controlling Exposure to Ionizing Radiation

Answer 19

Time Distance Shielding –– The general public shall not be exposed to more than 1 mSv per year. –– Occupational exposure shall not exceed 20 mSv per year.

Question 20

Controlling Exposure to Non-Ionizing Radiation

Answer 20

UV- Cover exposed skin, protect the eyes IR cover exposed skin, protect the eyes Microwaves and radio waves, maintain a safe distance from the source of radiation, Isolate Lasers (High-class lasers eye protection)

Question 21

Controlling Exposure to Radon

Answer 21

Positive pressure Radon sumps and extraction systems

Question 22

Types of examination in case of health surveillance for people exposed to radiation

Answer 22

Skin checks Respiratory checks Reference to exposure records Reference to sickness records

Question 23

State the six work-related causes of stress and, for each, give one example of a preventive measure.

Answer 23

• Demands – ensuring that there are sufficient resources available to do the work required and that priorities and deadlines are negotiated and reasonable. • Control – encouraging workers to plan their work, and make decisions about how it is completed and how problems will be tackled. • Support – providing positive feedback, and focusing on performance, not on personality. • Relationships – clear standards of conduct and policies to tackle harassment and bullying. • Role – clear work objectives, job descriptions and reporting responsibilities. • Change – consultation and involvement of staff in determining processes

Question 24

a)Outline the possible effects on health form exposure to high level of noise b)Outline two noise control techniques that would benefit all workers

Answer 24

On exposure to high levels of noise there is a range of health effects which the worker can experience. The cilia (hair cells) in the cochlea can become damaged, resulting initially in a temporary loss of hearing (a temporary threshold shift) with a possibility of tinnitus (ringing in the ears). This effect could ease once the worker leaves the noisy environment. However, repeated exposure could result in this becoming permanent (a permanent threshold shift) and this is what we understand as noise-induced hearing loss, with permanent tinnitus also possible. Workers in noisy environments may also experience stress and fatigue, as their sensory systems are overloaded and they may struggle to concentrate. If the noise is very loud (e.g. gunfire, explosive cartridges, etc.) there is a risk of physical damage to the eardrum and conductive bones in the inner ear. (b) Two possible noise controls which would benefit all workers are: • The use of sound-absorbing enclosures around the equipment, which use foam or mineral wool (or similar) on the inner walls which absorbs the sound and prevents transmission to the workers. • The use of anti-vibration matting (rubber matting or mounts) placed underneath equipment to absorb energy and prevent vibrations from being transmitted to the surrounding structure, generating noise. These are commonly used underneath pumps and motors.