Which Of The Following Is A True Statement Regarding Engineering Controls?

John Saunders (Health & Condom Laboratory)

Contents

• i Introduction
• 2 Definition
• three The Hierarchy of Control
• four Types and Examples of Engineering Controls
  • 4.1 Not-ventilation engineering controls
  • 4.2 Ventilation
    • iv.2.ane General Ventilation
    • iv.2.2 Local Exhaust Ventilation
• 5 Designing and Implementing Engineering Controls
  • v.i Design considerations
  • 5.ii Additional benefits of skilful control
• six Ensuring that Technology Controls are constructive and reliable
  • half dozen.ane Why engineering science controls oft fail to protect workers
  • six.2 Commissioning
  • 6.3 Worker Training
  • vi.iv Checks, Monitoring and Maintenance
• 7 Conclusion
• 8 References
• 9 Further reading

Introduction

The term 'Engineering Controls' covers a broad spectrum of possible interventions that are intended to reduce worker exposure, to chemic, physical and biological agents. This article will explain what 'Technology Controls' are with respect to chemical and biological agents and how they fit into the hierarchy of controls. Examples are given of engineering controls along with some advantages and limitations. The importance of matching the control measure to the health risk and its reliability is as well discussed along with commissioning. In one case command has been achieved the article volition explain why maintenance and checks are vital in order to maintain good control and therefore reduce worker exposure.

Definition

In the context of health and safety, an 'Engineering science Control' can be described equally a physical modification to a process, or process equipment, or the installation of farther equipment with the goal of preventing the release of contaminants into the workplace (adjusted from ^[1]). As tin can exist seen from this wide definition there are a wide range of applied science controls, which could be applied. The command selected volition depend upon the blazon of process, the nature of the contaminant source (its toxicity and release mechanism) and the road of exposure (inhalation, dermal, and ingestion). However, the reality is that no single engineering control in isolation will exist successful; control is always a mixture of equipment and ways of working.

The Hierarchy of Command

The approach to controlling the chemic hazard released from a procedure is rarely straightforward as at that place will ever be a selection of control options – some easier to apply than others. Notwithstanding, the approach taken should be based on a priority list. This principal of priority is ofttimes referred to as the 'Hierarchy of Control'. The European Command Hierarchy, as stipulated by Quango Directive 98/24/EC ^[2] gives the priority order and is summarised below:

1. Elimination of hazardous substances;
2. Commutation past a substance less chancy;
3. Design of appropriate work processes and engineering controls and employ of adequate equipment and materials, so as to avert or minimise the release of hazardous chemic agents which may present a run a risk to workers' safety and wellness at the identify of work;
4. Application of collective protection measures at the source of the chance, such as adequate ventilation and advisable organisational measures;
5. Where exposure cannot be prevented by other means, the application of individual protection measures including personal protective equipment (PPE).

The directive goes on to country that chancy chemical agents shall be eliminated or reduced to a minimum by:

• the design and organisation of systems of work at the workplace;
• the provision of suitable equipment for piece of work with chemical agents and maintenance procedures which ensure the health and safety of workers at piece of work;
• reducing to a minimum the number of workers exposed or probable to be exposed;
• reducing to a minimum the duration and intensity of exposure;
• advisable hygiene measures;
• reducing the quantity of chemical agents nowadays at the workplace to the minimum required for the type of work concerned.

Information technology should be noted that this hierarchical arroyo is non unique to Europe and is adopted past prophylactic professionals worldwide ^[iii]. From the above listing it can be seen that engineering controls are integrated into steps 1 to 4. For example it can exist argued that modifying a manufacturing procedure so as to eliminate the hazardous substance is a form of engineering control. However, it is common practice to associate technology controls with steps three and 4: i.e. one time emptying and commutation of chemic hazards accept been considered. At times engineering controls may not offer adequate control and may need to be supplemented with other measures. Ofttimes this will take the form of PPE, which includes respiratory protection equipment (RPE). As can been seen from the priority list, PPE is the last step if all other interventions fail to offer sufficient protection. The problem with PPE is that it just protects the wearer. For RPE this is of particular business organisation equally whilst the procedure operator may be protected from an airborne hazard, in one case it is released into the air it volition inevitably pervade the workplace and therefore expose others who are probable to be unprotected. Furthermore for RPE to be effective it needs to be properly selected and correctly fitted, making preparation and user cooperation essential.

Types and Examples of Technology Controls

It is not possible to list every different blazon and design of engineering controls, nevertheless they can exist broadly divided into ii types: non-ventilation and ventilation controls. Table i gives a wide range of examples of engineering controls, including both not-ventilation and ventilation (adapted from ^[4]. This listing is past no means exhaustive, only gives a flavour of the variety of controls available. Further examples of practiced practice can exist found in the European union-OSHA report The practical prevention of risks from dangerous substances at work [three]

Tabular array 1: Examples of technology controls

Process/Exposure source	Applied science command	Boosted procedural control
Cleaning with solvent on rag	(i) Employ a rag holder (ii) Provide a minor bin with a lid for used rags.	(i) Check controls are used (ii) Prophylactic disposal of waste
Grit spills from damaged sacks	Portable vacuum cleaners with HEPA filter	(i) Ensure vacuum is maintained and bachelor for employ (ii) Prophylactic emptying of vacuum cleaner
Cut-fluid mist from a lathe	Put an enclosure around the lathe and extract and filter the air and discharge to a safe place (Protective gloves will likewise be required)	(i) Train workers (e.k. Information technology takes fourth dimension for the mist to articulate from the enclosures and this clearance fourth dimension must exist known) (ii) Check and maintain fluid quality (3) Test and maintain controls (iv) Carry out health checks
Grit from disc cutter on rock worktop	(i) Carry out the process in an enclosure fitted with extraction, filter and excerpt to a safety place	(i) Exam and maintain controls (ii) Train workers (iii) Carry out health checks
Transfer of volatile liquids	(i) Pumping rather than pouring (ii) Tight fitting lids to minimise evaporation	Regular checks and maintenance (eastward.g. Check for harm to lids seals)
Evaporation of liquid from an electroplating tank	A layer of plastic balls floating on the surface to reduce both evaporation and mists	Check and maintain controls

Non-ventilation engineering controls

Not-ventilation controls have the capability to reduce or eliminate process emission rate, for example the utilise of well-fitting lids to liquid containers. They can range from enclosures, seals, jigs and handling aids. Still, engineering controls are frequently assumed to involve some form of ventilation command. This is unfortunate, equally whilst ventilation controls tin can exist effective and are the most commonly applied control to airborne contaminates, dismissing other not-ventilation engineering science controls can be a costly mistake both in terms of financial and health cost.

There is probably no single reason why not-ventilation methods of control are overlooked, but possibly the two primary reasons are:

(i) the perceived need to alter the process and the potential ramifications this entails, whereas ventilation is often seen as something that tin can be retrofitted to any process, with little or no process modification. The reality is that this approach often leads to poor and erratic control. Designing a ventilation system to effectively control airborne contaminants requires specialist advice. All also ofttimes ventilation systems are badly designed and installed, poorly maintained and therefore frequently fails to provide adequate command;

(ii) Ventilation is seen as a low cost option, which is not true. Besides as the capital cost required to purchase and install a ventilation system there are associated running costs. The latter includes power (required to bulldoze the air mover plus that required to heat/cool air that is brought into the workplace to replace the air extracted) and the maintenance costs, such as replacement filter units.

Ventilation

Unlike non-ventilation control, ventilation is unlikely to affect the emission rate from a process; rather it is designed to command the contaminant once it has been released.

As mentioned in above, ventilation controls are probably the nigh widely used method to command airborne contaminants in the workplace and can exist divided in to two types: general ventilation and local frazzle ventilation.

General Ventilation

Full general ventilation is the introduction of clean air into the workplace that eventually replaces the contaminated air. Full general ventilation tin can be subdivided into 2 further types: dilution ventilation and displacement ventilation.

The aim of dilution ventilation is to uniformly mix the clean air that is continually introduced in to the workplace with the contaminated air in society to dilute the contaminant concentration to an acceptable level. Whilst this is an accustomed form of engineering control, its application is express to low toxicity sources that are normally diffused throughout the workplace and where the workers are a sufficient altitude from the source(s).

Deportation ventilation is where air is introduced with the aim of replacing the contaminated air by clean air with little or no mixing. In practice this is difficult to attain, especially over big areas and therefore needs specialist assist. Both of the above types of full general ventilation tend to utilise a meaning corporeality of air, which unremarkably needs to be heated or cooled; consequently this blazon of ventilation is an expensive solution.

Local Exhaust Ventilation

Local Frazzle Ventilation (LEV) is designed to capture, receive or contain the airborne contaminant at source before it has gamble to enter the workers breathing zone or mix with the workplace air. As the control is practical as close to the source as possible, considerably less air is required when compared to full general ventilation and consequently LEV is typically more constructive in both terms of effectiveness and cost. For this reason LEV is preferred to full general ventilation and should be considered to be college in the hierarchy of controls.

Designing and Implementing Engineering Controls

Blueprint considerations

Whilst elimination or substitution of the chemical hazard is the almost effective solution, it is recognised that this is not always possible or straightforward. Ofttimes the process relies on the chemical in question and therefore elimination or substitution will non be an selection. Consequently applied science controls are practical that either:

• Reduce the emission rate from a process, usually by process modification (not-ventilation controls); or
• Capture or containment of the emission once it has been released from the process, usually by enclosing and air extraction (ventilation controls).

An example of reducing the contaminate emission rate is by the application of h2o to a stone cutting deejay. This significantly reduces the emission of dust, creating instead liquid slurry. It should be noted in this example disposal of the liquid slurry may create a further run a risk. An case of removal of the contaminant once it has been generated would be by the application of local exhaust ventilation. This would be accomplished by enclosing the process as much as possible and extracting the airborne contaminant with a relatively low volume, high velocity extraction organisation. Interestingly these two forms of technology command have like effectiveness ^[5].

The examples to a higher place illustrate that at that place is always more than than one engineering control approach that can be practical to any process and therefore it is important that the diverse engineering controls are collated and their suitability assessed earlier a solution is selected. When assessing the controls the following need to be considered:

• Effectiveness
• Reliability
• Ease of use, and of grade
• Financial cost.

Estimating the effectiveness of a control measure is non always easy and tin easily exist misjudged. Figure i illustrates simply that as potential exposure chance increases, the command effectiveness must too increase. Failure to do and so results in what is often referred to as the 'command gap' and information technology is this gap that results in worker exposure. The mismatch betwixt the effectiveness of the technology controls and the procedure risk can occur for a number of reasons, ranging from a lack of appreciation of the extent of the exposure take chances from the process, to an over optimistic conventionalities in the capability of the command measure.

Figure 1: Analogy of the consequence of mismatch between the hazard of exposure and the engineering command effectiveness

Source: Adapted from HSE training material

Before engineering controls tin can be contemplated it is necessary to understand how the contaminant is being released into the workplace. This requires a total understanding of how the process works and how workers interact with the process. Ideally workers should be involved in the pattern and selection of the controls, equally they will be using them on a daily basis. Failure to do this oftentimes results in engineering controls that are unworkable resulting in poor exposure control. Depending on the procedure, other disciplines may also need to be consulted, in particular the engineering function, as their input may be required to ensure the more intricate nuances of the process are considered and understood (for example quality of the final product is not affected by the introduction of the control measure).

Likewise as considering the procedure, the reliability of whatsoever proposed control measures needs to exist addressed. In that location is little signal designing and installing what is judged to exist an constructive control solution that only works intermittently and is prone to malfunction.

Some applied science controls are more difficult and time consuming to utilise than others and sometimes companies may accept to resort to RPE equipment as a temporary control measure until the final engineering controls are design and implemented.

Additional benefits of practiced control

Clearly engineering controls are designed to reduce exposure and to assistance companies in complying with health and safety regulations and occupational exposure limits. Still, it is possible that they may help to reduce environmental pollution and, importantly can make an economical bear on by reducing company expenditure on such items as product consumables. Two examples of this are given in European union-OSHA, Factsheet 33 - An introduction to unsafe substances in the workplace [four].

One of the examples was a printing facility that introduced covers on older, high-solvent, printing machines. This technology control required some thought, simply hardly any capital expenditure. As a result the solvent vapour levels were halved, saving 5,000 litres of solvent per calendar week equating to €74,400 a year. A clear case of an engineering control not only reducing worker exposure but saving the visitor a significant amount of money.

Ensuring that Engineering Controls are effective and reliable

Why engineering controls often fail to protect workers

Engineering controls tin fail for a variety of reasons. Often they are not as constructive every bit envisaged and therefore fail to protect from the date they are installed. Fifty-fifty when initially effective their performance can gradually decline. This tin be exacerbated past poor management, east.g. inadequate training. Therefore in that location are issues to consider in ensuring controls work effectively and proceed working.

Commissioning

Once a command measure out is designed and installed information technology needs to be deputed. 'Commissioning' is proving that the engineering command is capable of providing adequate exposure control. The type of commissioning and the complexity depends upon the control measure. Probably the well-nigh circuitous commissioning process is that of LEV systems. Unfortunately LEV commissioning is oftentimes carried out incompletely or is inadequate. LEV commissioning tends to focus on the engineering parameters, such as system pressures and air velocities. Whilst this is an essential part of the commissioning process, a judgement on the effectiveness of the controls and the worker exposure needs to be taken. In that location are a number of qualitative and quantitative tools available to help the assessor estimate control. An instance of a qualitative assessment is the use of smoke tubes to visualise the air flow in and around an LEV hood in guild to assess LEV performance. An example of a quantitative control is personal sampling to quantify worker exposure to a particular substance(s).

Worker Training

In isolation, an engineering control solution is destined to fail. They demand to be integrated with other control measures, such as a 'standard operating procedure'. Information technology is highly likely that some form of training and supervision volition also exist required to ensure that the controls are correctly used and therefore control workers' exposure.

Checks, Monitoring and Maintenance

Without regular checks and routine maintenance, the effectiveness of engineering controls will dethrone gradually and inevitably neglect. The fourth dimension it takes for this to occur volition depend upon the blazon of control measure. Engineering controls tend to degrade slowly with time and this oftentimes goes unnoticed. An instance of this are poorly maintained LEV systems; oftentimes the workers can hear the fan impeller rotating, simply do not realise that the volume flow rate of the system is imperceptibly falling with time resulting in a loss of control of the airborne contaminant. In this example the functioning of the LEV hood could be continually monitored by the employ of an air flow indicator, such as a pressure guess.

Decision

All likewise often when companies realise they have an exposure problem, they immediately assume PPE is the only solution. Invariably this is not the case, and following the hierarchy of controls, engineering controls that are properly commissioned and maintained play an important function in reducing the workers exposure to the chemic risk in the workplace.

References

1. ↑ Bullock, Due west. H. & Ignacio, J. S. (Eds.), A Strategy for Assessing and Managing Occupational Exposures, Tertiary Edition", pp. 426, American Industrial Hygiene Association, Fairfax, VA, 2006
2. ↑ EC - European Commission. Council directive 98/24/EC of 7 April 1998 on the protection of the wellness and safety of workers from the risks related to chemic agents at work (fourteenth private Directive inside the meaning of Article 16(one) of Directive 89/391/EEC), 1998. Available at: [1]
3. ↑ Perkins, L. J., Modern Industrial Hygiene: Volume 3 - Control of Chemic Agents, American Conference of Governmental Industrial Hygienists, Cincinnati, Ohio, 2012.
4. ↑ HSE - Wellness and Safety Executive, Working with substances hazardous to health. A brief guide to COSHH. Available at: [2]
5. ↑ HSE - Health and Safety Executive, On-tool Controls to Reduce Exposure to Respirable Dusts in the Construction Industry - A Review, RR926, 2012. Available at: http://www.hse.gov.uk/research/rrhtm/rr926.htm

Farther reading

Eu-OSHA – European Agency for Safety and Health at Work, 'An introduction to dangerous substances in the workplace', Facts No 33, 2003. Available at: [five]

EU-OSHA – European Agency for Prophylactic and Health at Work, Dangerous substances e-tool. Bachelor at: [6]

Eu-OSHA – European Agency for Safety and Health at Work, Practical tools and guidance on dangerous substances. Available at: [vii]

European union-OSHA – European Agency for Rubber and Health at Work, Info sheet: Substitution of unsafe substances in the workplace, 2018. Available at: [8]

EU-OSHA – European Agency for Rubber and Health at Work, Training form: Substitution of dangerous substances in workplaces, 2021. Available at: [9]

Eu-OSHA – European Agency for Safe and Wellness at Piece of work, Info sheet: Legislative framework on dangerous substances in workplaces, 2018. Available at: [10]

Piney, M., Alesbury, R. J., Fletcher, B., Folwell, J., Gill, F. South., Lee, J. L., Sherwood, R. J. & Tickner, J. A., Controlling airborne contaminants in the workplace, British Occupational Hygiene Society (BOHS) Technical guide no 7 (TR7), 1987.

Which Of The Following Is A True Statement Regarding Engineering Controls?,

Source: https://oshwiki.eu/wiki/Engineering_controls

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