Section A Questions Deck 1

Question 1

Construction workers regularly use cement. Several of the long-term workers and one of the new recruits have complained about red and sore skin on their hands.

1. Explain possible reasons for the symptoms that they are experiencing. (6)
2. Outline control measures that could be used to minimise these symptoms. (4)

Answer 1

a) The symptoms suggest that the workers are suffering from dermatitis caused by a chronic or repeated exposure to an irritant or irritants. Cement is a known irritant that can cause allergic contact dermatitis through contact with a sensitizer - chromium VI compound impurities in the material - that produces an over-reaction from the body’s immune system.

Sensitization can occur on the first contact such as with the new recruit or after some time in the case of the long-term workers.

The effect of contact with the irritant/sensitizer de-fats and degreases the skin and overcomes the skin’s own defense and repair systems.

The symptoms could also be caused by caustic burns whilst friction and abrasion from general floor laying and a failure to protect the hands with gloves and a good standard of personal hygiene will not help the condition.

b) The control measures that could be used to minimize the symptoms such as:

• Using a non- cement-based compound, for example, a polymeric compound.
• Wearing gloves to protect the skin and minimizing contact using hand tools.
• Providing washing facilities so that contaminants can be washed from the skin as soon as possible with the hands dried thoroughly after washing.
• Using pre-work and after-work moisturizing creams to replenish the natural oils in the skin.
• Giving information to the workers on the importance of carrying out their own skin inspections and encouraging them to report any problems with their skin; and
• Arranging for supervisors to carry out regular skin inspections of the workers.

Question 2

Workers cutting and finishing stone are exposed to silica dust. Outline factors to be considered when carrying out a ‘suitable and sufficient assessment of the risks from exposure to silica dust. (10)

Workers cutting and finishing stone are exposed to stone dust. Stone dust has been assigned a legally enforceable Occupational Exposure Limit (OEL).

(a) Give the meaning of ‘Occupational Exposure Limit’ (OEL). (3)
(b) Explain the factors to be considered when undertaking a suitable and sufficient assessment of the risks from exposure to stone dust. (11)
(c) Outline a suitable range of control measures that could reduce the risk to these workers from exposure to stone dust. (6)

Answer 2

1. An occupational Exposure Limit (OEL) is the maximum concentration of a substance to which workers may be exposed by inhalation. The concentration is measured in mg/m3 or ppm and is averaged over a reference period, either long term over a period of eight hours intended to control effects by restricting the total intake by inhalation over one or more work shifts, or short term, usually fifteen minutes, to control effects that may be seen after a brief exposure. For the control of stone dust to be adequate the OEL should not exceeded, and the principles of good hygiene practice should be followed.
   b. In undertaking an assessment of the risks from exposure to stone dust, factors to be considered include

• The health effects of the dust such as irritation to the skin, eyes and respiratory tract (physical structure such as crystalline or amorphous may also have a bearing on longer term health effects);
• The number of persons exposed the level, duration and frequency of their exposure and the susceptibility of individuals such as to asthma;
• The routes of entry of the dust such as through inhalation or ingestion;
• The particle size of the dust which will determine how far into the body the dust will pass;
• The way in which the work is carried out whether by hand or power tool;
• The level and effectiveness of existing control measures and results from the monitoring of airborne contaminants and their comparison with the OEL together with the results of health surveillance.

c. As for suitable control measures, for operations carried out in a workshop,

• The use of local exhaust ventilation would be required but for outside work damping down would be the measure that would have to be used.
• Controls to be used in both situations include the use of cutting tools with in-built extraction or a damping spray;
• The provision and use of respiratory protective equipment (RPE) which should be comfortable to wear for extended periods of use, and compatible with other personal protective equipment such as eye and hearing protection, gloves and overalls; and
• Facilities both for washing, changing and for the laundering and storage of overalls.
• RPE users should also be subject to face-fit testing and the RPE itself properly cleaned and stored when not in use.
• Training for workers on hazards and precautions was also relevant.

Question 3

Outline the main design features of the following parts of a Local Exhaust Ventilation (LEV) system:

(a) inlet/hood; (2)
(b) ducting; (3)
(c) fan; (2)
(d) outlet / exhaust. (3)

Answer 3

(a) it should have considered features of the inlet or hood such as its shape and size, the material of its construction, its capture and face velocity and its positioning in relation to the contaminant source.
(b) As for ducting, there would be a need to address its internal finish and the nature of its bends, the material of its construction, its transport velocity and the access provided for testing and maintenance.
(c) The type of fan required whether centrifugal or axial and propeller giving reasons for the choice, the speed and power required and the possibility of the level of noise it might produce.
(d) As for the outlet or exhaust, design features include its positioning, the avoidance of cowls, its ability to achieve environmental standards at the point of discharge and again the level of noise that might be produced.

Question 4

Bulldozer drivers at a large construction site have reported back pain which they believe is caused by exposure to whole-body vibration.

(a) Outline a range of control measures that could be used to minimize the risk of the drivers experiencing back pain caused by exposure to whole-body vibration. (7)
(b) Identify THREE other possible work-related causes of the back pain being experienced by the bulldozer drivers. (3)

Answer 4

(a) Control measures include

• Selecting a vehicle with the size, power and capacity best suited for the terrain and task;
• Ensuring that an individual’s exposure to whole body vibration (WBV) is kept below the recommended threshold;
• organising traffic routes used by vehicles to avoid rough and uneven surfaces wherever possible and maintaining both the site roadways and the vehicles’ suspension;
• Fitting suspension seats with vibration damping characteristics and adjusting these to suit the weight of individual drivers to avoid “bottoming out”;
• Organising work patterns including job rotation to ensure that drivers have breaks away from the vehicle and
• Advising them on how to minimise exposure to whole body vibration by avoiding jolts and shocks.

(b) The other possible work-related causes for the back pain include

• Poor posture;
• Sitting for long periods of time;
• The poor layout of controls requiring the driver to stretch and twist to reach a particular control or to obtain good vision;
• No method provided for adjusting the seat which could make hand and foot controls difficult to operate;
• The repeated climbing into and jumping down from a high cab and carrying out other construction related activities such as the manual handling of heavy loads.

Question 5

(a) Use the data below to calculate the 8-hour Time-Weighted Average (TWA) exposure to a solvent for a factory worker. Your answer should include the detail of calculation to show your

understanding of how the exposure is determined. (7)

Assuming that exposure is zero during all other times

Also, assume that a legally enforceable Exposure Limit (8 hours TWA) of 100 ppm is applicable to the solvent

(b) The factory decides to change the working patterns so that each worker does a single job for a 12-hour shift. A factory worker is assigned the job of charging the mixers for his 12-hour shift.

Within the shift, he is allowed two 45-minute breaks where the exposure is assumed to be zero.

Using the relevant data above, recalculate the equivalent 8-hour TWA exposure in the worker’s new role AND outline the legal implications of this change. (3)

Answer 5

a) How the 8-hour TWA exposure to the solvent for the worker could be calculated:

Firstly, by multiplying together each time period and exposure including the periods of zero exposure, then adding the results of the calculations together and finally dividing by eight (8).

This would give an answer of 75 ppm.

Numerically, this could be expressed as:

((140 x 2.5) + (0 x 0.25) + (100 X 2) + (0 X 1) + (25 X 2) + (0 X 0.25))/8

= 350 + 0 + 200 + 0 + 50 + 0 = 600

600/8 = 75 ppm. This is below the legally enforceable exposure limit of 100 ppm.

(b), a similar calculation would have shown an exposure of 131.25 ppm viz:

((100 x 10.5) + (0 x 1.5))/8 = 1050/8 = 131.25

The change in the mode of working has increased the individual’s exposure so it is now more than the legal exposure limit and accordingly the employer is no longer adequately controlling the exposure and must introduce additional controls

Question 6

Identify a range of information sources an employer could use to

determine the extent of work-related stress for workers within an

organization. (10)

Answer 6

There are several information sources available that employers might use to determine the extent to which workers in their organisations have a work-related stress problem.

• These include measures of productivity (such as volume or quality of work),
• data on accidents and incidents and levels of sickness absence;
• health surveillance data and medical reports;
• records of staff turnover and poor or erratic timekeeping.
• The number of complaints received from workers and the grievances or discipline problems that have arisen,
• information available from the completion of:
  
  • staff questionnaires or from
  • performance appraisals or
  • return to work or
  • exit interviews and
• the results of an assessment of performance carried out against published stress management standards.

Question 7

The table below shows data provided in a supplier’s catalog for three different grades of the same industrial chemical.

Use the data to identify where EACH of these powders may be deposited in the respiratory tract following inhalation. In EACH case outline the mechanisms the body may use to defend itself. (10)

Answer 7

The particle size will determine how far into the body the chemical will penetrate.

For AS1/01, the particles are greater than 10 microns therefore they will enter the nasal cavity only. The nasal hairs will trap and filter out these particles. They may also be trapped by mucous in the nose and mouth and subsequently ejected by sneezing and coughing.

As far as AS1/02 is concerned, particles between seven and ten microns reach the Respiratory track (trachea and bronchioles). They are swept upwards by tiny hairs - the ciliary escalator- towards the throat and are then removed either by coughing or swallowing.

Particles smaller than 5 microns, as for AS1/03, are likely to reach the deep lung tissue. When deposited in the alveoli, they may diffuse directly into the blood stream and be transported to other organs, trigger a defence mechanism where phagocytes engulf the particulate as a foreign body and migrate away through the lymphatic channels or may stay in the spaces in the lungs and depending on their chemical properties may cause fibrosis or pneumoconiosis.

Question 8

Workers in a chemical plant are provided with gloves to protect against the possible effects of the chemicals. In recent months, there has been an increase in the number of hand and lower arm skin complaints amongst these workers.

Outline possible reasons for this increase in skin complaints. (10)

Answer 8

The possible reasons for the increase in skin complaints such as:

• An incorrect initial selection of the protective gloves both as far as their material was concerned and their size and fitting.
• The fact that the gloves had degraded over time and had not been replaced or had been damaged either accidentally or intentionally with workers cutting off the finger ends to increase their dexterity/skill;
• The possibility of workers having an allergy to materials such as latex or the presence of excess perspiration following long periods of use;
• The failure to give the workers training in the methods to be adopted in putting on and removal of the gloves, and in the importance of self-examination, personal hygiene and the use of after-care products;
• A failure to clean gloves after use and to store them away from contaminants;
• The absence of a system for reporting defects and replacing the protection;
• Inadequate levels of supervision to ensure workers used the gloves at all times and
• finally the possibility that a new chemical together with a change in process and work methods has been introduced.

Question 9

a) Identify the way in which lasers are classified according to their hazard. (2)
(b) Low power lasers are widely used to read bar-code labelled products at checkouts in retail premises.

Outline:

(ii) the design features; (4)
(ii) the procedural controls (4)

that should be in place for the safe operation and maintenance of the equipment

Answer 9

a) The classification of lasers is defined in an IEC standard - IEC 60825 (also EN 60825).

The classifications are based on accessible emission levels with the power of the lasers measured in milliwatts (mW). There are seven different classifications - 1, 1M, 2,2M, 3B, 3R AND 4 the graduation in the level of hazard associated with each class are from Class 1 - the lowest level to Class 4 lasers which pose the greatest hazard.

b) i) The design features that should be incorporated into the laser products to ensure their safe operation and maintenance include:

• the laser having no greater power than Class 1;
• the use of embedded systems;
• the fitting of a protective housing with trigger operation on the handheld version;
• incorporating a key control with interlock to the power source;
• the provision of signage and the appropriate positioning of the laser, including hand-held equipment, to avoid eye-level exposure.

ii) Procedural controls include strict observance of the manufacturer’s guidance and training workers in the safe use of the equipment for example:

• warning them that they should not look directly into the beam;
• drawing up and introducing a safe system of work for the maintenance and repair of the equipment;
• ensuring that if the case is to be removed, it requires a special key or tool and that the beam is properly controlled.
• introducing a procedure for reporting defects and ensuring that any maintenance and repair of the equipment found to be necessary is carried out by a competent person.

Question 10

Workers on a food production line have to pick up rectangles of pasta from a delivery conveyor and place them into trays on a separate conveyor. This involves 8-hour shifts and is carried out standing in front of the conveyors.

Following complaints from a number of workers about pains in their arms and shoulders, you have been asked to carry out an ergonomic assessment for this operation.

(a) Outline the ergonomic risk factors to be taken into account when making such an assessment AND outline how these may be contributing to the problems experienced by the workers in this situation. (5)
(b) Total automation of the process is not possible. Outline other control measures that could be taken to reduce the ill-health effects being experienced by the workers. (5)

Answer 10

a) In carrying out an ergonomic risk assessment of the operation described in the scenario, the factors that would need to be taken into account include:

• The individuals factors, such as worker height;
• The repetitive nature of the task involving frequent movements of the upper body to pick up the pasta and place it in foil trays;
• The continuous nature of the operation over an eight hour shift;
• The posture adopted by the operators including standing and reaching from one conveyor to another;
• The expected work rate and the speed of the conveyors;
• The height of the conveyor in relation to that of the individual workers and the total pattern of continuous work with the number and length of the breaks allowed.

(b) Control measures to reduce the ill-health effects include:

• Adjusting the height of the conveyors and re-positioning them in parallel;
• Arranging the work so that it might be carried out from both sides of the conveyor to prevent overreaching;
• Providing seating for the operators to enable them to change their position from time to time;
• Reducing the speed of the feed conveyor;
• Using scoops or other tools to pick up the pasta;
• Introducing job rotation with other less demanding tasks;
• Providing information to the workers on the benefits of changing their posture and stretching on a regular basis; carrying out pre-employment health screening to determine existing problems which might make applicants unsuitable for the task and introducing health surveillance and encouraging workers to report any problems that might arise.