Risk Analysis

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Journal of Occupational and Environmental Hygiene

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Risk analysis for confined space entries: Critical analysis of four tools applied to three risk scenarios

Damien Burlet-Vienney, Yuvin Chinniah, Ali Bahloul & Brigitte Roberge

To cite this article: Damien Burlet-Vienney, Yuvin Chinniah, Ali Bahloul & Brigitte Roberge (2016) Risk analysis for confined space entries: Critical analysis of four tools applied to three risk scenarios, Journal of Occupational and Environmental Hygiene, 13:6, D99-D108, DOI: 10.1080/15459624.2016.1143949

To link to this article: https://doi.org/10.1080/15459624.2016.1143949

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JOURNAL OF OCCUPATIONAL AND ENVIRONMENTAL HYGIENE , VOL. , NO. , D–D http://dx.doi.org/./..

Case Study Column Editor: Eun Gyung Lee

Risk analysis for confined space entries: Critical analysis of four tools applied to three risk scenarios

Reported By Damien Burlet-Vienneya,b, Yuvin Chinniahb, Ali Bahloula, and Brigitte Robergea

aInstitut de recherche Robert-Sauvé en santé et en sécurité du travail, Montreal, Quebec, Canada; bMathematics and Industrial Engineering Department, Polytechnique Montreal, Montreal, Quebec, Canada

KEYWORDS Confined space; hazard identification; risk analysis; risk estimation

ABSTRACT

Investigation reports of fatal confined space accidents nearly always point to a problem of identify- ing or underestimating risks. This paper compares 4 different risk analysis tools developed for con- fined spaces by applying them to 3 hazardous scenarios. The tools were namely 1. a checklist with- out risk estimation (Tool A), 2. a checklist with a risk scale (Tool B), 3. a risk calculation without a for- mal hazard identification stage (Tool C), and 4. a questionnaire followed by a risk matrix (Tool D). Each tool’s structure and practical application were studied. Tools A and B gave crude results com- parable to those of more analytic tools in less time. Their main limitations were lack of contextual information for the identified hazards and greater dependency on the user’s expertise and ability to tackle hazards of different nature. Tools C and D utilized more systematic approaches than tools A and B by supporting risk reduction based on the description of the risk factors. Tool D is distinc- tive because of 1. its comprehensive structure with respect to the steps suggested in risk manage- ment, 2. its dynamic approach to hazard identification, and 3. its use of data resulting from the risk analysis.

Introduction

Confined space work is regulated in most industrialized countries.[1–5] A confined space is defined in the U.S. Occupational Safety and Health Administration (OSHA) regulation as “a space that: (1) is large enough and so configured that an employee can bodily enter and per- form work; (2) has limited means of entry or egress; and (3) is not designed for continuous employee occu- pancy.”[1] Regulations set out requirements regarding worker qualifications, hazard identification, atmospheric control, monitoring of entry and egress, and rescue pro- cedures. In addition, standards respecting confined spaces provide guidelines on the management program to be set up, the roles and responsibilities of stakeholders, the asso- ciated planning (e.g., training, emergency response plans) and the application of work permits.[6,7]

CONTACT Damien Burlet-Vienney [email protected] Institut de recherche Robert-Sauvé en santé et en sécurité du travail,  boulevard de Maisonneuve Ouest, Montreal, Quebec, HA C, Canada. Color versions of one or more of the figures in the article can be found online at www.tandfonline.com/uoeh.

Supplemental data for this article can be accessed at tandfonline.com/uoeh. AIHA and ACGIH members may also access supplementary material at http://oeh.tandfonline.com/.

The distinguishing feature of confined space acci- dent prevention is its multidisciplinary nature, including atmospheric hazards (i.e., poisoning, asphyxiation, explo- sion), as well as biological, physical (e.g., mechanical, electrical, engulfment, falling, lighting, vehicle traffic) and ergonomic hazards.[8–10]

Investigation reports of fatal confined space acci- dents nearly always point to a problem of identifying or underestimating risks. Work activity and rescue were improvised and no work procedure was followed.[11,12] As a result, risk reduction measures were inappropri- ate or inexistent. Risk assessment and the implementa- tion of a program, training, permits and other elements, thus appears to be important. Typically, risk assessment involves 2 stages, namely risk analysis (i.e., identifica- tion of hazards and risk estimation) and risk evaluation (i.e., judgement of whether the risk reduction objectives

©  JOEH, LLC

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Table . Description of the three confined space work scenarios used for testing  tools.

# Manhole/Inspection # Manhole/Installation # Tank truck/Welding

Use of confined space Type Manhole – Sewer system. Tanker truck tank. Function Access to sewer system pipe. Transportation of diesel fuel. Equipment inside space Old sewer pipe at th level. Low water pressure, can increase during storms. No equipment. Drains and intakes for

refuelling.

Configuration of confined space Location Sidewalk. Near traffic lane. Shelter adjoining garage. Accessibility Entrance easily accessible. Tank entrance ( m high). Access by

ladder. Description of interior  levels, each  m high. Levels made of metal grating ( m ×  m). No obstacles.

No lights. Cylindrical tank: . m in diameter,  m

in length,  compartments. No lights.

Entrances/exits : regular entrance (circular,  m in diameter) and auxiliary (square,  m each side). : one for each compartment (<  m in diameter).

Means of access to interior Ladder rungs set into cement for regular entry. Appears to be in good condition. Ladder to be placed in tank. Appears to be in good condition.

Contents No stored substances. Wet metal grating. Diesel. Tank emptied, steam-cleaned and rinsed with water.

Outside conditions Temperature °C °C Weather conditions Stormy Sunny Sound environment Noisy Quiet Chemicals nearby None None

Planned work Work Visual inspection of concrete at st level. 

worker. Installation of measuring instruments at th level.  workers.

Welding to repair bottom of tank compartment.  worker.

Tools Conventional tools (e.g., hammer, trowel). Power tools ( V) and conventional tools (e.g., pliers). Basket and rope for lowering and raising them.

Welding equipment. Solution for cleaning surface to be repaired.

Length, frequency  min., twice a year.  hr,  min. Once every  years. Several trips in and out anticipated.

 hr. Once every  years.

Miscellaneous Open access to lower levels. Open access to lower levels. °C at th level.

N/A

have been achieved).[13] According to a study of 15 orga- nizations that had implemented a confined space entry management program, businesses seem to have trouble formalizing the hazard identification and risk estimation stages when preparing for confined space work. Indeed, half of the organizations did not conduct any preparatory analysis (e.g., risk fact sheets) before issuing an entry per- mit, and none of the organizations quantified the identi- fied risks.[12]

Otherwise, a review of the literature on risk manage- ment for confined space work found that the main tools suggested for risk analysis are checklists, risk scales, and risk matrices.[14] A number of problems have been asso- ciated with these tools, however. The checklists suggested are often incomplete. The main problem of scales is that there is no criterion to choose the level of a risk.[15] More- over, matrices suggested give more guidance to estimate risks but remain generic.[5,8] Definitions used are vague and parameters are not adapted to the particular charac- teristics of confined spaces (e.g., multiple types of risks, interactions among hazards).[16] To our knowledge, no study has compared the use and effectiveness of different tools for confined space risk analysis.

Research objective and method

The objective of this study was to compare four different tools developed for performing risk analysis in confined space environments. The research team tested each tool on three risk scenarios. Tool structure, use, and results were investigated.

Confined space work scenarios

Three scenarios were developed based on work observed in business settings or in accident reports. Each scenario was associated with a distinct overall risk level (i.e., low, medium, high) in order to cover a wide range and to detect any bias in the risk estimating tools. No risk reduc- tion measures were considered when applying the four tools to each of the three scenarios.

As shown in Table 1, the first two scenarios concern the same confined space which is a manhole providing access to sewer system (Figure 1), but two different work assign- ments (i.e., inspecting concrete at the 1st level for scenario #1; installing measuring instruments at the 4th level for scenario #2). Scenario #3 consists of one worker welding

JOURNAL OF OCCUPATIONAL AND ENVIRONMENTAL HYGIENE D101

Figure . Manhole providing access to sewer system—Scenarios # and .

to repair the bottom of the tank compartment of a tanker (Figure 2).

Scenario #1 was considered a priori to be a low-risk scenario, as the potential harm seemed minimal for a visual inspection. Scenario #2 was considered to be a medium-risk scenario, chiefly because of the high poten- tial harm of fall. Scenario #3 was considered a priori to be a high-risk scenario on account of the possibly fatal harm that can result from welding (e.g., poisoning).

Risk analysis tools

Four types of tools were selected: checklist (Tool A), risk scale (Tool B), risk calculation (Tool C), and a risk matrix (Tool D).[18–21] Tools that dealt only with atmospheric risks were excluded from the selection pro- cess.[5,22] Although we tested only the risk analysis part (i.e., hazard identification, risk estimation) for each scenario, all the information presented in the tools was analysed. In the countries where these tools have been published, it was not mandatory to use them.

Figure . Tanker wash facility—Scenario #.[]

Checklist (Tool A) There are several checklists available for risk analysis by businesses and universities.[23,24] We selected a check- list tool used by a major corporation whose confidential- ity was guaranteed by our study’s research ethics certifi- cate.[18] Table 2 shows an example of the checklist applied to scenario #1.

Risk scale (Tool B) With the selected risk scale tool, risks can be estimated according to four levels or rankings: extreme, high, mod- erate, and low.[19] Hazards are identified by means of a predefined list. The application of Tool B to scenario #2 is presented in Table 3. A column for the main risk reduc- tion measures is provided in the tool but not presented in Table 3.

Risk calculation (Tool C) The tool we selected has two parameters for estimating risk: likelihood of injury and severity of injury. Com- bining the two parameters leads to three risk ratings (Table 4).[20] There is no formal part for identifying haz- ards. The application of Tool C to scenario #3 is presented in Table 5.

Questionnaire and risk matrix (Tool D) Tool D is a five-step risk assessment tool. [21] Step 1 consists of a questionnaire to describe the configuration of the selected confined space, its environment and the work situations (see the table in the supplementary file). The answers generate predefined types of risk split in seven families: atmospheric, chemical, biological, falling, mechanical, physical, and ergonomics. Answers to the questions also suggest a characterization of rescue condi- tions (i.e., rescue without entry is possible or not; prevail- ing conditions make a rescue with entry more complex or not). Step 2 describes the components of risks (i.e., haz- ards, hazardous activity, hazardous event, harm). Step 3 estimates risk using two risk parameters and matrix (see the table in the supplementary file). Following the risk analysis, step 4 summarizes risk families and ratings, in chart form (Figure 3). The value associated with a risk class (i.e., 1–4) corresponds to the maximum risk level reached among the risks it includes. An estimate and a summary of the residual risks following the choice of risk reduction measures are also available (step 5). Table 6 shows the results obtained for step 3 of Tool D applied to scenario #3. Steps 4 and 5 were not used for the testing.

Comparison criteria

Before a tool was applied, its structure was evaluated on the basis of the following points:

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Table . Company’s risk analysis checklist (Tool A) applied to scenario #.[]

Atmospheric/chemical hazards Biological hazards Physical hazards

Lack of oxygen � Pathogenic microorganisms � Various power supplies � Falling � Oxygen enrichment � Dirty/rusty parts � Mechanical � Slippery surface � Flammable contaminants � Other � Electric shock � Noise � Toxic contaminants � Thermal (heat) � Entrapment � Toxic chemicals � Hot surface (contact) � Engulfment, drowning �

Chemical burns � Internal layout � Pressure (stored) � Worker isolated � Visibility (lack of) � Falling object � Difficult access or egress � Other �

Table . Risk scale (Tool B) applied to scenario #.[]

Risk

Potential hazards Extreme High Moderate Low

Nature of the confined space X Access and Egress X Electrical X Lighting X Power Failure X Contaminated air X Flammable gases X Extreme temperatures X Fire X Introduced materials X Other contaminants X Activation of plant X Method of work selected X Level of oxygen X Possibility of explosion X Unauthorized access X Floor Access Drop (use ladder) X Lack of PPE Other: traffic, falling object X

1. comparison with risk management steps recom- mended in standards,[25]

2. means to ensure risk analysis is exhaustive and sys- tematic,

3. use of the estimated risks (e.g., categorization of risks), and

4. construction of risk estimation and criticism in relation to chosen architecture.[13,16,26–28]

Then, the time required for each analysis, ease of use, the list of hazards, as well as the subjectivity and precision of the possible answers were also noted.

Results and discussion

Tests

The results obtained by the research team over the 12 tests (4 tools on 3 scenarios) are presented in Table 7. The first column of the table shows all the different hazards iden- tified with the four tools for the three scenarios. When a box is empty, it implies that the risk has not been identi- fied when using that tool for the scenario. Thus, this table allows comparing both the risks found with each tool and the estimation of the risks for Tools B, C, and D. The risk levels obtained are specified in the form “estimated risk level/number of risk levels in tool.” The structure of the four tools selected and the characteristics of their usabil- ity are presented in Table 8. These results are discussed in the following sections.

Table . Tool C presented in form of matrix[].

Severity

Likelihood

TRIVIAL [] Injuries that could be treated by local First

Aiders from a First Aid box

SLIGHT [] Injuries that may require more expert

treatment, administered at a medical centre / hospital

department

SERIOUS [] Injuries involving urgent hospital treatment

MAJOR [] Injuries involving major trauma or death

MOST LIKELY [] Injury probable

   

LIKELY [] High possibility of injury

   

UNLIKELY [] Injury a conceivable occurrence

   

MOST UNLIKELY [] Probability close to zero

   

Risk Rating Action Required  or  Existing control measures may be considered adequate  or  Consider introduction of additional controls or supervision  or higher Additional controls are required in the form of a Safety Programme and Permit to Work

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Table . Confined space risk assessment  form (Tool C) applied to scenario #[].

Generic hazards Caused by/Source? Likelihood (a) Severity (b) Risk rating (a × b) Oxygen deficiency Welding    Restricted entrance Diameter <  m    Fall from height Tank opening >  m high    Fall from height Vertical entrance (. m)    Falling object Vertical opening    Fall on same level Curved, slippery tank    Toxic contaminants Welding fumes    Flammable contaminants Diesel + welding    Chemicals Cleaning products    Hot surface Welding    Noise Welding    Body posture at work Cramped +  h of labour    Introduction of substances Drains    Vehicle movement Moving truck    Radiation Welding    Electricity Welding    Heat stress Welding   

Checklist (Tool A)

A checklist is a hazard identification tool. The main advantages are its speed and ease of use, which is why businesses prefer it. But the disadvantage is a lack of pre- cision for risk reduction purposes. The tool does not pro- vide any context for the identified hazards and their origin (e.g., related to the specific work or the confined space). For example, in the case of scenario #1, a risk of falling is indicated, but the tool does not specify two different risk situations: entry and access to the second floor. In addition, the proposed list of hazards is incomplete when compared with the other tools. For instance, ergonomic hazards and rays or radiation are not included, and

Figure . Tool D: Summary of risk estimation before risk reduction measures applied to scenario #.[] Reprinted from Safety Science, , Damien Burlet-Vienney, Yuvin Chinniah, Ali Bahloul, Brigitte Roberge, Design and application of a  step risk assessment tool for confined space entries, —, Copyright , with permis- sion from Elsevier.

mechanical hazards (e.g., nip points, mobile confined spaces) are not specified.

Another issue was that the tool did not define a level of risk. A risk will be mentioned if it is not deemed accept- able by the user. “Risk acceptance is the deliberate deci- sion to assume a risk that is low enough with respect to the probability of a hazard-related incident or exposure occurring and the severity of harm or damage that may result, and which is considered tolerable in a given situa- tion.”[29] This decision depends on many factors, includ- ing training, experience, and resources available. When checklists are used, the reasoning behind and basis for selecting or not a hazard is not documented. It can lead to repeatability issues for the same user or different users for the same situation.

Risk scale (Tool B)

This tool has the same advantages and disadvantages as the checklist for identifying hazards. It requires more tedious work compared to the tool A because hazards are not classified into families (e.g., atmospheric, biological) but less time compared to other Tools C and D. Also, some of the potential hazards listed are hard to interpret due to lack of detailed information, such as “lack of PPE” and “method of work selected.”

The difference between the risk scale and the checklist is that the former uses an ordinal scale to estimate risks. Although it is still more valuable to have a risk scale rather than qualitative decision based on the checklist, an eval- uation of this scale based on the construction rules pro- posed by Chinniah et al. for risk estimation tools shows that it suffers from “poor definition.”[32] This problem consists in using single words or vague terms to define the levels of risk, of likelihood of harm or of severity of harm. Vague language like this can lead to bias in the estimation

D104 D. BURLET-VIENNEY ET AL.

Table . Step  of Tool D: Results of the risk estimation step (without the activities part) for scenario #[].

Origin Class Type Source S P Risk

Confined space Atmospheric Oxygen deficiency Welding Serious Likely  Confined space Atmospheric Explosion/fire Flammable product (gas) Catastrophic Likely  Confined space Chemical Corrosive product Gas Minor Unlikely  Confined space Falling Fall from height Vertical access Serious Unlikely  Confined space Falling Fall from height Access at height Catastrophic Likely  Confined space Ergonomic Inadequate light No light Minor Likely  Confined space Ergonomic Entry/egress Opening <mm Minor Likely  Confined space Ergonomic Work posture Small internal volume Minor Likely  Confined space Mechanical Mobility of space Confined space on a truck Serious Likely  Confined space Physical Drowning Wastewater pipe Minor Very unlikely  Work to be done Atmospheric Poisoning Welding gas Catastrophic Likely  Work to be done Chemical Corrosive product Welding product Minor Unlikely  Work to be done Falling Falling on the same level Curved surface Serious Likely  Work to be done Ergonomic Physical exertion Duration of work Minor Likely  Work to be done Ergonomic Heat stress Welding Minor Likely  Work to be done Physical Noise Tools Serious Likely  Work to be done Physical Electricity Tools Major Unlikely  Work to be done Physical Electricity Temporary light Major Unlikely  Work to be done Physical Optical radiation Welding Major Very likely  Work to be done Physical Heat Welding - Surface Serious Very likely 

Reprinted from Safety Science, , Damien Burlet-Vienney, Yuvin Chinniah, Ali Bahloul, Brigitte Roberge, Design and application of a  step risk assessment tool for confined space entries, —, Copyright , with permission from Elsevier.

process and significantly influence the final result.[30,31] During testing, the choices proved to be completely intu- itive and therefore depended on the user’s’ judgement. The results of the estimation, on the other hand, were comparable to those of Tools C and D, except for falling from height, falling objects and traffic risk, which were underestimated. In these cases, severity of harm seemed to be underestimated compared to Tools C and D. For the purposes of a professional risk assessment, the prob- lem would therefore seem to be not the accuracy of the

estimation, but rather the identification and documenting of the factors contributing to the risk.

Risk calculation (Tool C)

Tool C does not include a formal hazard identification step. It is based on the user’s experience or on an addi- tional description of the confined space at this stage. This configuration can lead to some hazards being overlooked, especially considering that confined space accident

Table . Risk outcomes over possible outcomes or classes for scenarios , , and  for different hazards described in the tools.

Scenario # Scenario # Scenario #

Hazards A B C D A B C D A B C D

Lack of oxygen X / / / X / / / X / / ¾ Pathogenic microorganisms X / / / X / / / Traffic X / / / X / / / Fall from height (empty space) X / / / X / / / X / / / Fall from height (when entering) / / / / / / Fall on same level X / / / X / / / X / / Falling object X / / / X / / / / / Tools (movement, cut) / / X / / / Animals (bite, stress) / / Exposure to weather / / Toxic contaminants X / / / X / / / Intro. of substances, drowning X / / / X / / / Electricity X / / / X / / / Ambient temperatures X / / / X / / / Noise X X / / Restricted entrance/exit X / / / Explosion, fire X / / / Chemicals (residue) X / / / Chemicals (other) / Hot surface X / / / Body posture at work / / Vehicle movement X / / / Radiation / / / Restricted entrance/exit X / / / Physical exertion /

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Table . Structure and usability of four types of tools.

Tool type

Checklist Risk scale Risk calculation Questionnaire + Matrix Context definition Information required about targeted confined space and work to be done Hazard identification List of possible answers Set list of hazards N/A Questionnaire and validation Risk estimation N/A Choice among  risk

levels/ratings  parameters that lead to  risk levels

Matrix with  parameters and  risk levels

Risk evaluation N/A N/A Actions required according to  risk levels

Acceptable risk level adjustable by user

Risk reduction List of possible answers Other steps N/A N/A Estimation of residual risks Estimation of residual risks,

Work categorization, Characterization of rescue, in principle

Time per scenario <  min  min  min  min Ease of use and understanding of tool

Easy: checkboxes Easy: tick off risk level/rating Demanding: no help for identifying hazards

Demanding: very detailed

prevention is a multidisciplinary problem. This is sig- nificant because if risk identification is not practiced well, the rest part including risk reduction can become crippled.[32]

This tool takes longer and is more complex to use than the first two tools. The two parameters (i.e., like- lihood and severity) and the risk index provide guid- ance for risk reduction by highlighting certain risk factors. The tool can also be used to estimate residual risks once risk reduction measures have been taken. Risk assess- ment is no longer completely intuitive, as it is for a risk scale, but partly analytic (rule based). The results are easier for a business to use because it can standardize the risk estimation step and focus on the risk reduction measures.[33]

However, some shortcomings in the risk estimation process can be identified. First, the definitions for the two highest levels of the two parameters are inconsistent. For instance, it is hard to distinguish between high possibil- ity of injury and probable injury or between urgent hospi- tal treatment and major trauma. Second, regardless of the degree of likelihood, choosing between serious or major severity has no effect on the final risk rating. Similarly, regardless of the severity, choosing an occurrence likeli- hood of likely or most likely has no influence on the result. As a result, prioritization of risks is difficult. To conclude, the severity of the injury should be presented and cho- sen before the likelihood of injury, as the injury needs to be known in order to be able to assess its likelihood of occurrence.

Questionnaire and risk matrix (Tool D)

Tool D has a distinctive structure, which formally goes through all the steps suggested in risk management standards. Another unique feature is its dynamic haz- ard identification stage. The questionnaire includes a

detailed list of hazards. This aspect ensures that the hazard identification stage, which is absolutely essential, will be handled systematically. Of the four tools, this one produced the most complete list of identified hazards (e.g., ergonomic hazards, radiation, animals and stress). Another advantage of the questionnaire is that it also pro- vides a means of contextualizing risks, as it pinpoints the origin of the hazard and the physical source. For example, the results of scenario #3 itemized the different situations related to the risk of falling from height (e.g., when climb- ing down into the tank or down from the roof of the tank) and the risk associated with toxic chemicals (e.g., diesel and cleaning solution residues).

Compared to the previous tools, this tool takes a longer time in specifying activities by the user (∼ 20 min). The risk estimation stage has the same general characteris- tics as Tool C, and the risks obtained are comparable. However, the term “unlikely” has a different meaning in Tool C (positive, i.e., injury is conceivable case) and in Tool D (negative, i.e., harm should not occur during the work). This point illustrates the importance of clarify- ing the levels of parameters in order to eliminate misin- terpretations by the user. Nevertheless, certain structural problems raised regarding matrix (e.g., inconsistent defi- nitions) are correctly addressed.[34]

Otherwise, the level of acceptable risk can be deter- mined by user. This choice could be either a strength (i.e., providing flexibility) or a weakness (i.e., requiring expert advice). It should be used to lower the level of acceptable risk and not to increase it.

Finally, the tool allows the user to visualize the risk estimation results and communicate them more easily (Figure 3). It also details how the different strategies (i.e., eliminate risk at design stage, reduce hazard intensity or need to enter through design, incorporate collective means of protection, apply technical or administrative procedures and PPE use) impact the severity and the probability of occurrence of harm.

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Table . Advantages and limitations noted for each tool with regard to hazard identification and risk estimation.

Advantages Limitations

Hazard identification Checklist (Tools A and B) Quick, effective Intuitive Satisfactory overview Easy

to use in the field Not sufficiently exhaustive, systematic Interuser

variability, depends on user competency, no well-defined hazards and hazardous situations No information on source and origin of hazard. Analysis must be completely redone if work changes

Questionnaire-suggestion (Tool D) Dynamic approach, more exhaustive and systematic Contextualized hazards. No need to redo analysis completely if work changes Usable at design stage

Fairly long process Must be used by qualified person, in part in office setting

Risk estimation Risk scale (Tool B) Quick, effective Risk levels determined close to

those obtained with analytic tools Easy to use in the field

Risk factors not made explicit and documented Interuser variability, depends on user competency

Risk calculation (Tool C), Risk matrix (Tool D) Questioning and documenting of risk factors Criteria for risk acceptability and assessment of effectiveness of risk reduction measures Better convergence of interuser results if risk matrix appropriate Usable at design stage

Lengthy process Estimation that is still qualitative and partly subjective, and should be regarded as such Must be used by qualified person, in part in office setting

Tool comparison

Table 9 compares the four tools in terms of hazard iden- tification and risk estimation. Tools that have the same advantages and limitations are grouped together. Check- lists and risk scales are quick to use and give acceptable results in comparison with the other tools, but provide only a relatively superficial analysis of a situation. They rely more on a user’s instinct and experience. Tools C and D offer more precise information about the risk factors involved. Tool D is also more systematic to its question- naire. This is a significant advantage in the context of con- fined spaces, where a wide variety of risks requires multi- disciplinary expertise. The risk analysis takes much longer than with the other tools, however.

Conclusion

The objective of this study was to compare four differ- ent tools recommended in the literature or in business for confined space risk analysis by applying them to three risk scenarios. Those four tools were: 1. a checklist without risk estimation, 2. a checklist with a risk scale, 3. a risk cal- culation tool without a formal hazard identification stage, and 4. a risk matrix with a questionnaire.

Checklist and risk scale tools, which were favored by businesses, proved to be quick to use and provide accept- able results in relation to the other tools. Their limitations have to do with their lack of contextualization for iden- tified hazards (e.g., no information about the source or origin of a hazard) and their greater reliance on the user’s competency for identifying hazards. The likelihood of overlooking risks is high, which limits the scope of these tools. They are therefore better suited for an initial overall

analysis of a situation. Tools C and D represent more sys- tematic approaches that make it possible to ask questions about risks, to identify risk factors and to document the analytic process. These tools also offer support for the risk reduction process by providing criteria for assessing risk acceptability and residual risks. These tools can produce more homogeneous results from one user to the next (i.e., repeatable results) indicating that the architecture of the risk matrix is free of obvious bias (e.g., inadequate or inconsistent definitions of parameter levels, predominant influence of one parameter). These tools require devoting more time to analysis than the other tools do, which can limit their usefulness in business.

Tool D has a distinctive structure, which formally goes through all the steps suggested in risk management stan- dards. It also differs from the other tools that its haz- ard identification stage is very exhaustive by requiring answers of the user about risk factors related to the config- uration of the confined space, the work environment and the work itself. Tool D also makes use of hazard identi- fication and risk estimation results by categorizing risks and rescue conditions. It also details the impact of the different strategies used to reduce risks for interventions in confined spaces on the component of the risk. These data could be useful at the design stage of the confined space.

Funding

The authors wish to thank the Institut de recherche Robert- Sauvé en santé et en sécurité du travail, located in Montreal, Quebec, for funding this research. This study was conducted as part of a project approved by Polytechnique Montreal’s Com- mittee on the Ethical Conduct of Research Involving Human Subjects (CÉR-12/13-02).

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