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NEBOSH NEBOSH INTERNATIONAL DIPLOMA IN OCCUPATIONAL HEALTH AND SAFETY Unit IB: International control of hazardous agents in the workplace WEDNESDAY 4 JULY 2012 3 hours, 0930 to 1230 10 minutes reading time is allowed before the start of this examination. You may not write anything during this period. Answer both Section A and Section B

SECTION A

This section contains six questions. Answer ALL SIX questions.

All questions carry equal marks.

The maximum marks for each question, or part of a question, are shown in brackets.

You are advised to spend about 15 minutes on each question.

Start each answer on a new page.

1 (a) Outline the meaning of the term ‘work-related violence’. (2) (b) Outline a range of practical measures to help reduce violence towards a

nurse who is required to visit patients in their own home. (8) 2 According to current veterinary and medical opinion, the bacterium E. coli O157

should be assumed to be carried by all ruminants (cattle, sheep, goats and deer). In addition, this bacterium can exist for long periods of time outside the animal (in soil and faeces).

(a) Identify ways in which school children visiting a farm might be exposed to

E. coli O157 bacterium. (4) (b) Explain a range of practical control measures that should be put in place

to reduce this risk of exposure. (6)

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3 A company has decided to close its offices and allow its 30 workers to work from home. The company will provide each worker with their own portable (laptop) computer for use at home and on their daily visits to customers.

Outline factors to consider when selecting and using these laptops to minimise

ergonomic risks. (10) 4 The figure below shows an audiogram for an adult worker.

Thr

esh

old

shift

(d

B)

(a) Explain what is meant by ‘threshold shift’. (2) (b) Outline the significance of the shape of the audiogram. (2) (c) Outline the benefits AND limitations of audiometry as part of a hearing

conservation programme. (6) 5 Hand-Arm Vibration Syndrome (HAVS) can be caused by frequent and prolonged

use of hand-held power tools. (a) Identify the signs and symptoms of HAVS. (2) (b) Outline a range of control measures that could be used to minimise the

risks to workers of developing HAVS when using such power tools. (8)

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6 (a) Outline what is meant by the term ‘biological monitoring’ AND give examples where such monitoring may be appropriate. (6)

(b) Outline practical difficulties that an employer must overcome when

introducing a programme of biological monitoring. (4) SECTION B

This section contains five questions. Answer THREE questions only.

All questions carry equal marks.

The maximum marks for each question, or part of a question, are shown in brackets.

You are advised to spend about 30 minutes on each question.

Start each answer on a new page.

7 A new health club is planning to install ultra-violet (UV) tanning equipment. The

equipment uses UV sources with a higher intensity than normal sunlight to accelerate tanning.

(a) Identify BOTH the acute AND chronic effects that could result from

exposure to UV radiation. (4) (b) Outline control measures that should be put in place for BOTH workers

AND customers for the safe operation of this facility. (12) (c) Outline TWO other examples of occupational exposure to UV radiation. (4) 8 (a) Explain why it is difficult to determine whether cancers in the working

population are caused by exposure to substances used at work. (6) (b) Outline the merits and limitations of EACH of the following methods for

identifying the carcinogenic potential of a substance: (i) human epidemiology; (5)

(ii) animal studies; (5)

(iii) in vitro mutagenicity (AMES) testing. (4)

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9 In a chemical process, workers use a mixture that contains two organic liquids, MMA and PPO. Table 1 below shows the average personal exposure levels to the organic liquids for one worker measured over an 8-hour day and Table 2 shows the exposure limits for the two components (MMA and PPO).

Table 1

Task undertaken by worker Duration of task

Exposure to MMA (ppm)

Exposure to PPO (ppm)

Measuring out and adding mixture to process vessel

15 minutes 70 200

Adding other components to the mix

1 hour 20 200

Supervision of mixing 2 hours 35 200 Transfer of product to containers 2 hours 40 200

Assume that exposure is zero at all other times. Table 2

Substance Exposure limit Long-term exposure limit (8-hour TWA limit reference period)ort-term exposure

Short-term exposure limit (15-minute reference period) 15-minute

MMA 50 100 PPO 200 250

(a) Substances in a mixture may interact in different ways to cause harm.

Outline what is meant by independent, additive and synergistic interactions. (4)

(b) Using the information in Table 1, calculate the 8-hour Time-Weighted

Average (TWA) exposure of the worker to BOTH MMA AND PPO. (8)

Your answer should include detailed working to show you understand how the exposure is determined.

(c) Using relevant information from Tables 1 and 2, explain what actions

might be required by the employer to control exposure. Assume that the components have independent toxic action. (8)

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10 A contractor is hired to fit a noticeboard in a small meeting room in an office block. This task involves drilling through some asbestos insulating board.

(a) Outline the diseases caused by exposure to asbestos including their

health effects. (7) (b) Outline the issues the contractor should consider when assessing the risk

of exposure to asbestos arising from this task. (5) (c) Outline control measures the contractor should take when carrying out

this task. (8) 11 An airborne contaminant has an Occupational Exposure Limit (OEL) of 10ppm, 8-

hour Time-Weighted Average (TWA). Engineering controls have been introduced but the airborne concentration of the contaminant in a workshop has been measured at 180ppm, 8-hour TWA.

The occupational hygienist has selected an item of Respiratory Protective Equipment (RPE) with an Assigned Protection Factor (APF) of 20, which is to be worn temporarily by all workers in the contaminated area.

(a) Using the data above, outline how the occupational hygienist could have

calculated the APF AND whether the hygienist made an appropriate selection. (4)

(b) Outline other factors that should be taken into account when selecting

appropriate RPE. (6) (c) When RPE is used it may not provide the level of protection stated by the

manufacturer. Outline the possible reasons for this. (10)