risk assessment tools techiniques and their applications

List of Tables xix17.8 Sample Sources of Information for a Vulnerability Study 275 18.2 Process Steps for Checking a Chip Detector 281 18.3 Failures Associated with Each Step 281 18.4 Ef

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Risk Assessment

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Published by John Wiley & Sons, Inc., Hoboken, New Jersey.

Published simultaneously in Canada.

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Library of Congress Cataloging-in-Publication Data:

Ostrom, Lee T., author.

Risk assessment : tools, techniques, and their applications / Lee T Ostrom, Cheryl

1 Introduction to Risk Assessment 1

vi Contents

5 Task Analysis Techniques 56

Step 2: Determine Required/Critical

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13.3.2 Chemical Reactor Critical Function

Contents xi

18 Developing Risk Model for Aviation Inspection and Maintenance Tasks 277

xii Contents

22 Industry Specific Case Studies 346

List of Figures

10.1 SCRAM actions for Verify Rods Inserted The operations

personnel should validate this sequence of steps and the

10.4 Another view of Verified Rods 144

10.5 HRA event structure of coolant flush procedure 150

11.1 Process map from interview 156

xiv List of Figures

11.3 Generic process map for trade group 158

11.4 Simple incident process map 159

12.2 Event tree with path probabilities 165

12.3 Event tree for a portion of a small-break LOCA 166

12.4 Event tree for Tulsa event figure 168

13.1 Interconnection of critical functions 189

13.2 Flight during an engine failure event 189

13.3 Critical functional analysis for convenience store 194

13.4 Critical functional analysis of a chemical reactor system 195

13.5 Critical functions during process upset 196

13.6 Rural county critical functions 200

14.1 Switches representing AND gates 208

14.2 Switches representing OR gates 208

14.3 Fault tree analysis of coolant flushing task 214

14.4 Partial fault tree of sprinkler system failure 216

14.5 Fault tree for success model 216

14.6 Fault tree for TAM Linhas Aereas Flight 3054 220

16.1 Quantitative research step process 239

16.3 Example of the design for the visual crack study given to

18.2 Event tree with path probabilities 287

19.1 General layout of the Medium City 297

19.2 Fault tree for chemical release event for location A 303

19.3 Fault tree for chemical release event for location C 306

21.4 Sample fault tree for chemical A or B spill 341

21.5 Sample fault tree for ignition source 342

22.1 Robot arm and unitized doses of medications 347

22.2 Station where robot arm drops unitized doses in bag for

22.3 Unitized doses of medication on the pick rack 348

22.4 Unitized dose packaging (a) Step 1: drug is selected (b)

Step 2: pills are poured onto packaging machine

(c) Step 3: pills are loaded into hopper (d) Step 4: pills

List of Tables

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xviii List of Tables

12.2 Event Sequence with Probabilities 165

12.4 Accident Classification and Associated Cost 172

12.7 Events to be Analyzed in Chernobyl Event 179

13.1 Functions of the Major Components of a Space Shuttle 182

13.2 Lower Level Crew Life Support Functions of Orbiter 183

13.3 Critical Functions of a Commercial Airplane 188

13.4 Flight Critical Systems for F-22 Raptor 191

13.5 Critical Functions for Continuity of Operations 198

13.6 Secondary Critical Continuity of Operations Functions 200

14.3 More Complicated Logic Gates 209

14.4 Rules for Constructing Fault Tree 210

List of Tables xix

17.8 Sample Sources of Information for a Vulnerability Study 275

18.2 Process Steps for Checking a Chip Detector 281

18.3 Failures Associated with Each Step 281

18.4 Effect of Potential Failures 282

18.5 Complete FMEA for Chip Detector Task 283

18.7 Event Sequence with Probabilities 286

19.2 Preliminary Hazard Analysis for Site A 299

19.3 Preliminary Hazard Analysis for Site B 301

19.4 Preliminary Hazard Analysis for Site C 304

19.5 Probabilities for Basic Events 306

19.6 Chemical Release Spill Calculations 307

21.1 Key Issues in 1983 Phillips Explosion 321

21.2 Time line of Events Leading to the Texas City Explosion 325

21.5 Plant Component Reliability Data 331

21.6 Sample Preliminary Hazard Analysis for Process Plant 332

21.7 Sample Failure Mode and Effect Analysis for Process Plant 335 21.8 Fire Event Tree for Process Analysis 338

21.9 Event Tree Sequence for Chemical Fore and Subsequent

xx List of Tables

22.3 Four Parts of the Airport Security Screening Process

22.6 Food Safety Preliminary Hazards 372

23.1 Restaurant Risk Assessment 377

edit-Dawn Dieckmann for her help with reference checking.

Warren “Dewey” Plaster, John Ostrom, David E Fry, RochelleMason, Val Sealey, Eric Roy, and Louis Valenti for their contri-butions to the case studies

Kyle Williams for critical review of the document early in its life.Laura Ostrom for the chapter titled Risk of an Epidemic

Also, all the graduate students who provided comments or mation over the years

infor-C H A P T E R 1

Introduction to Risk

Assessment

working, going to school, driving or taking mass transit to work, ing at home or on vacation, or even working at home Some peopleare even finding the time to sleep Those who are working performjobs that range from cleaning animal kennels to being the head ofstate of a country and every type of job in between Every job, in fact,every activity a human performs, has a hazard associated with it Thecommon hazards we all are exposed to include

relax-• slips, trips, and falls;

accidents;

individual sports accidents (skiing, water sports, skate boarding);

• electrical;

Risk Assessment: Tools, Techniques, and Their Applications, First Edition.

Lee T Ostrom, Cheryl A Wilhelmsen.

 2012 John Wiley & Sons, Inc Published 2012 by John Wiley & Sons, Inc.

2 CHAPTER 1 Introduction to Risk Assessment

On top of these more common hazards, every job has specifichazards associated with it The major hazards associated with cleaninganimal cages, for example, include

waste;

of construction, and sharp edges;

jagged metal or wood, and faulty locks/latches/gates/door;

(HVAC) system in the building;

The major hazards associated with being a head of state include

• stress from political rivals;

the President of Poland died in an airplane crash in Russia in

2010 (1).)

Hazardous occupations, for instance, fire fighting, have numeroushazards associated with day-to-day activities Risk assessment toolsand techniques can be used to analyze individual jobs for risks It isobvious that every activity the President does is analyzed for hazards.Jobs or tasks such as fire fighting, chemical plant worker, electrician,and even office workers are usually analyzed using tools such as jobhazard analysis (2)

The focus of this book is on analyzing complex systems, tasks, andcombinations of tasks for hazards and the associated risks Most of themajor accidents that occur each year result from a series of events thatcome together in an accident chain or sequence and result in numerous

CHAPTER 1 Introduction to Risk Assessment 3

deaths, environmental consequences, and property destruction Theseaccidents can occur anytime in the system’s life cycle One of theevents from history that demonstrates this is the sinking of the Swedishship Wasa (pronounced Vasa) on August 10, 1628 (3) The ship wasfabricated between 1626 and 1628 In those days, engineering of theships was performed by the shipwright, and he used his experience

to determine factors such as center of mass and the amount of ballastthe ship should have Because of various events, pressure was put onthe shipbuilders to complete the ship ahead of the planned deliverytime The ship was completed and ready for sail on August 10, 1628.The ship was very ornately decorated and was heavily laden witharmament As the ship left port on its maiden voyage on that calmmorning, a gust of wind hit the ship, filling her sails The ship heeled

to port and the sailors cut the sheets The ship righted itself, but thenanother gust of wind hit the ship and it tipped to port far enough thatwater entered the gun ports This was the event that led to the loss

of the ship and approximately 30–50 lives However, the loss of theship was probably due to one of the two design flaws The first factorbeing that the ship was probably too narrow for its height, and second,the ship did not carry enough ballast for the weight of its guns on theupper decks A contributing factor was the height above sea level

of the gun ports that allowed water to enter the ports when the shiplisted to port Since, as stated above, engineering of ships was moreseat of the pants than a systematic design process, the real reason(s)for the disaster can only be speculated The ship was raised from herwatery grave in 1959 and has since been moved to a beautiful museumfacility in Stockholm Therefore, the ship itself can be studied, butother factors such as whether the guns were properly secured, howmuch provisions were on the ship, and so forth will remain a mystery.The Wasa accident occurred in the ship’s initial phases of its life cycle.Accidents can occur in any phase of a system’s life cycle

A much more recent accident occurred on December 24, 2008,

in Rancho Cordova in which a natural gas leak caused an explosionand fire, killing one person and injuring five others including onefirefighter and a utility worker The explosion also destroyed onehouse completely and severely damaged two others adjacent to thedestroyed house Several other houses in the neighborhood weredamaged Pacific Gas and Electric Company, the utility ownerand operator, operates 42% of California’s natural gas pipe lines

4 CHAPTER 1 Introduction to Risk Assessment

According to Pacific Gas and Electric Company, the property damagefrom this explosion and fire was $267,000 (4) The incident involvedpiping that had been originally installed in 1977 and repaired in

2006 The accident investigators found that a piece of piping that wasused in the repair was actually polyethylene pipe used as packingwhen transporting the ASTM D-2513 grade polyethylene piping.The wall thickness of the packing piping did not meet specificationsand there were no print lines of the piping used in the repair Therepair personnel, for whatever reason, selected a piece of the packingpiping as the repair material, rather than ensuring the pipe was of theproper grade Therefore, as with the Wasa event, human error wasthe primary driver in the event Although, in both events, hardwarecomponents were involved as well

Risk assessment tools and techniques, if applied systematically andappropriately, can point out these types of vulnerabilities in a system.The key term here is “systematic.” A risk assessment must be sys-tematic in nature to be most effective A risk assessment should beginearly in the life cycle of complex systems Preliminary hazard analysis(PHA) is an example of a tool that can be applied at the earliest phase

of system development As the design of a system progresses othertools can be applied, such as failure mode and effect analysis (FMEA)and fault tree analysis (FTA) Probabilistic risk assessment (PRA) andhuman reliability analysis (HRA) are techniques used to analyze verycomplex systems These tools usually require a well-developed design,

an operating philosophy, and at least working copies of procedures toprovide enough material to perform analyses However, even maturesystems benefit from risk assessments The analyses performed on thespace shuttle after the Columbia accident are a good example (5).These assessments pointed out vulnerabilities of the space craft thatwere previously unidentified or viewed as being not as important.Using the six sigma/total quality management philosophy of con-tinuous improvement, risk assessment techniques applied throughoutthe design life of a system can provide insights into safety that mightarise at various points of the system’s life cycle (6) Reliability engi-neers use the bathtub curve to illustrate the classic life cycle of asystem (Fig 1.1) (7) In the first part of a system’s life, there is

a higher potential for early failure The failure rate then decreases

to a steady state until some point in the future when systems wear out

or old age failure occurs

CHAPTER 1 Introduction to Risk Assessment 5

Steady-state (random) failures

Early failures or

infant mortality

Wear out or old age failures Warranty limit

FIGURE 1.1 Bathtub curve.

Manufacturers usually warranty a system, a car for instance, forthe period of time from birth till just before system wear out Thisway they maximize their public image, while minimizing their risks

or obligations

Risk analysts are also interested in such curves but from a safetyperspective Accidents commonly occur early in a system’s life cyclebecause of several reasons, including

The system then enters a long phase of steady-state operation that,

as long as no changes perturbate the system, remains safe In latersystem life, accidents occur for the same reason as why systems wearout, components wear out However, in terms of accident risk, when

a component fails in old age it might lead to a catastrophic failure

of the system, for instance, the Aloha Flight 243 accident (8) In thiscase, the aircraft structure had become fatigued with age and failedduring takeoff Workers have fewer accidents in their later workingyears; however, the severity of the injuries may be greater (9) Inaddition, latent conditions can lay dormant for many years in a system(10) These conditions could be a piece of bad computer code or a

6 CHAPTER 1 Introduction to Risk Assessment

piece of substandard pipe that when challenged leads to a failure.Performing risk assessments on systems throughout their life cyclecan help to elucidate these vulnerabilities Once these vulnerabilitiesare found, measures can be taken to eliminate them and/or mitigatethe consequences of failures This is the most important step of anyrisk assessment That is, eliminating the vulnerabilities and reducingthe risk of a system

1 What can go wrong?

2 How likely is it?

3 What are the consequences?

Chapter 2 of this book defines risk in depth

Probability is defined as a measure of how likely it is that someevent will occur (12)

Hazard is defined as a source of potential damage, harm, or adversehealth effects on something or someone under certain conditions atwork (13)

Severity is defined as the degree of something undesirable (12).Consequence is defined as the effect, result, or outcome of some-thing occurring earlier (12)

Vulnerability is defined as a weakness in a system or human that

is susceptible to harm (12)

Threat is defined as a source of danger (12) Threat and hazardare considered analogous

1.2 PERFORMING RISK ASSESSMENTS

There is no absolute rule as to how a risk assessment should beperformed and to what depth it should be performed The NASA

1.3 Risk Assessment Team 7

PRA guide (14) provides some recommendations and the NuclearRegulatory Commission (NRC) provides numerous guideline docu-ments on the topic (15) The Occupational Safety and Health Admin-istration’s (OSHA) “Process Safety Management of Highly HazardousChemicals” regulation (29CFR1910.119) (16) requires hazard analy-ses be performed for certain types of chemical operations, and theDepartment of Energy (DOE) specifies risk assessments for certaintypes of facilities (17) However, it is still up to the organization todecide how in depth the analysis should be This book discusses toolsthat are effective for performing risk assessments, but the decision

as to when to use the tools is up to the risk analyst Table 1.1 vides a list of the risk assessment tools discussed in this book and

pro-at whpro-at point in an analysis they are traditionally used In addition,this book provides other techniques that can be used to enhance a riskassessment, such as task analysis for determining human actions in

a process, the Delphi process for eliciting human error probabilities,and the critical incident technique for developing risk scenarios

1.3 RISK ASSESSMENT TEAM

Risk assessment is a systematic, step-by-step approach for evaluatingrisk It is the process for determining the probability of a risk occur-ring and the consequence of that risk It is a fundamental component

of an effective risk management program This program is a basicmanagement tool consisting of risk assessment and risk control Riskassessment is the data gathering component, while risk control is theapplication of the risk assessment evaluation

1.3.1 Team Approach

Individuals will respond to a risk or perception of a hazard based ontheir influences, environment, and biases What one person may per-ceive as a relatively low risk, another may consider highly dangerous

no matter what controls are in place If one or two individuals areasked to perform an assessment, some relevant factors may be missed

or ignored When determining the best course of action for ing a risk assessment, it is important to remember people will bringtheir own perceptions Even in respect to experts, different experts will

perform-8 CHAPTER 1 Introduction to Risk Assessment

TABLE 1.1

Risk Assessment Tools

Preliminary hazard

analysis (PHA)

This tool is used in the very beginning of a risk assessment and/or on a conceptual design of a new system, process, or operation.

It is used to determine the potential hazards associated with

or the potential threats poised to a system, process, or operation.

This tool is also useful for organizations to evaluate processes that have been performed for years to determine the hazards associated with them.

10

Event trees Event trees are very useful tools to

begin to analyze the sequence of events in potential accident sequences They also have utility

in analyzing accidents themselves.

Many variations of event trees have been developed This book presents some of the more common ones.

12

1.3 Risk Assessment Team 9

TABLE 1.1

Fault tree analysis

called the top event Although this

analysis tool is used to quantitatively determine the overall probability of

an undesired event, it is also useful from a qualitative perspective to graphically show how these events combine to lead to the undesired event of interest FTA has a wide range of use from determining how one’s checking account was overdrawn, to determine why a space shuttle crashed.

in complex operating environments such as aviation, transportation, the military, or medicine HRA is used to determine the human operators’

contribution to risk in a system.

of all the other risk assessment tools and techniques to build an integrated risk model of a system A fully integrated PRA of a nuclear power plant, for instance, can take years to perform and can cost millions of dollars It is reserved for the most complex of systems.

15

10 CHAPTER 1 Introduction to Risk Assessment

perceive different risks and from those perceptions, conclude differentresults or controls In general, you want to bring together a group ofpeople who work in the environment to work together as a team

1.3.2 Team Representatives

Before any assessment of the risks can be started, a determination ofwho should be involved or who makes up the risk assessment teamneeds to be considered The right group of people with the right mix

of experience The team will be between 5 people up to 10–15, ifnecessary The team will include people from all sorts of differentjobs and experience

Risk assessment is never a one man show; it should be conducted

by a multidisciplinary team, who has a thorough knowledge of thework to be undertaken Team members should include management,process or facility engineers, technical personnel, supervisors, produc-tion operators, maintenance staff, and safety personnel, if available.The team members will vary from assessment to assessment, com-pany to company, and industry to industry, but the following elementsare common:

1 Management should be involved to give practical application

in the decision-making process of risk reduction controls andaccepting residual risk level

2 Engineers should be involved in the risk assessment process,

as they are involved in the development of the design decisionsthat will impact the overall risk and risk controls

3 Workers/Operators/Supervisors should be involved andincluded in the team, as these people are the most familiarwith the tasks and uses for which the assessment will directlyeffect These are the individuals best suited to identify thepossible hazards associated with the end use They can providevaluable insights on the possible controls and the practicalapplication of those controls

4 Health and Safety Professionals, if available, can offer

valu-able insights into what control measures might be availvalu-able.They can identify possible hazards and propose risk reductionmethods and their application

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References 11

5 Maintenance is another component that needs to be represented

to understand the ramifications of implementing controls on thesystem or process being assessed

The goal of the risk assessment team is to reduce risks to tolerable

or acceptable levels This assessment is completed by

1 identifying hazards and/or potential hazards;

2 identifying users and/or tasks;

3 determining the level of risk;

4 evaluating potential controls—elimination, substitution,

engi-neering controls, administration controls, and/or use of personalprotective equipment;

5 developing a report;

6 implementation and review.

The resulting risk assessment report must be evaluated, approved,and endorsed by senior management

3 Cederlaund CO Vasa I, The Archaeology of a Swedish Warship of 1628; 2006.

4 Available at www.ntsb.gov: www.ntsb.gov/pulictn/2010/PAB1001.pdf Retrieved

12 CHAPTER 1 Introduction to Risk Assessment

9 Available at http://.osha.europa.eu: http://osha.europa.eu/en/prioritygroups/ ageingworkers/hazards html Retrieved 2011 Jan 25.

10 Reason, J (1990) Human Error New York: Cambridge University Press.

11 Kaplan S, Garrick B On the quantitive definition of risk Risk Anal 1981; 1:11–27.

12 Available at http://wordnetweb.princeton.edu: http://wordnetweb.princeton.edu/ perl/webwn Retrieved 2011 Jan 25.

13 Available at www.ccohs.ca: http://www.ccohs.ca/oshanswers/hsprograms/hazard risk.html Retrieved 2011 Jan 26.

14 Available at www.hq.nasa.gov: www.hq.nasa.gov/office/codeq/doctree/praguide pdf Retrieved 2011 Jan 26.

15 U.S NRC Available at http://www.nrc.gov/reading-rm/doc-collections/nuregs/ staff/sr1855/v1/sr1855v1.pdf Retrieved 2010 Dec 31.

16 (n.d.) Available at www.osha.gov: http://www.osha.gov/pls/oshaweb/owastand display standard group?p toc level =1&p part number=1910 Retrieved 2011 Jan 25.

17 (n.d.) Available at www.doe.gov: www.doe.gov Retrieved 2011 Jan 26.

C H A P T E R 2

Risk Perception

In casual use, risk implies negative consequence while opportunityimplies positive consequence (1)

Perception is the process of interpreting sensory stimuli by filtering

it through one’s experiences and knowledge base Note that perception

is not the same as sensation, as the latter term is physiological and theformer is learned (2)

Taken together, risk perception is an individual or group ment of the potential for negative consequence Within emergencymanagement circles, understanding the public’s general perception ofrisk (for instance, the isolated opinion contains peaks and valleys) isuseful in establishing the necessary level of preincident emergencytraining, public relations and instructions/recommendations during theincident, and postincident continuing communications Risk perceptionplays into the choices made as to what information is to be providedand in what format—both inside the affected organization and outside.From the company’s management structure to its blue-collar workers

assess-to its colocated workers assess-to the neighboring suburbs and beyond, riskperception is as close to “the facts” as each person gets until theirvision is altered by some later, greater truth

Like the proverbial two-edged sword, risk perception both servesand hinders emergency management (EM) organizations and, subse-quently, those protected and supported by the EM function At one

Risk Assessment: Tools, Techniques, and Their Applications, First Edition.

Lee T Ostrom, Cheryl A Wilhelmsen.

 2012 John Wiley & Sons, Inc Published 2012 by John Wiley & Sons, Inc.

14 CHAPTER 2 Risk Perception

tapered end of the spectrum lies a band of Chicken Littles pointing atthe blue sky and warning of dire consequences; at the opposite, there

is a huddle of frumpy white-coated scientists swaddled in disdain.The majority of us lay somewhere between these two, our placement

in demographics split into hundreds, even thousands, of layered andskewed bell curves based on age and income, experience and educa-tion, and innumerable other facets It’s the endless variability of thepublic that makes risk perception such a difficult management issue.But it can be managed

While it is safe to say that there is a near-endless variation in ception, cataloging allows one to build boxes around like perceptionsuntil they are within a defined set To build these boxes, you need toknow what factors affect the audience’s perception Is the subject mat-ter highly technical and beyond the bulk of the area’s laymen? Doesthe vicinity you are considering have decades of experience with yourparticular industry? Has that experience resulted in bad blood?

per-To understand what knowledge is relevant to your evaluation ofthe audience’s risk perception, you have to consider the business youare in Examples of heightened sensitivity (and negative perception)are those where the technology involved borders on black magic tothe layman Fission and fusion and government weapons facilitiescome immediately to mind, followed by sprawling laboratories wherethe workers say little about what goes on inside their white walls.The less he knows, the more Joe Q public thinks and wonders and,ultimately, worries As a matter of comparison, let us consider twohazards commonly found in high population areas: liquid petroleumgas and lawn care chemicals

Liquid petroleum gas (LPG), AKA LPG AKA propane, is a mon fuel in the city and the country, in industrial areas and rural areas,and at homes and businesses Small containers, such as those used forbarbeques, propane-powered vehicle fuel tanks, and camp trailers can

com-be found literally everywhere Larger containers, such as 30,000-galbulk tanks for distributors, can be found in most cities across thecountry At pier side, where massive ships unload, tanks may carry asmuch as 50,000 tons of propane

Decades of use and familiarity have made modern man able with propane The 250- and 500-gal tanks available at manygas stations are no cause for concern (to the point that few of thoseoperating them even wear protective gloves or a face shield during

comfort-2.1 Knowledge Level 15

propane handling) The racks of refillable barbeque propane bottlesstored outside most grocery stores are not either Nor are the multipletractor-trailers carrying thousands of gallons of propane across townand on every freeway

A quick calculation shows that the 6000 gal of propane on anygiven tanker truck contains approximately 549 million BTU—equal

to 138.4 tons of TNT or just over nine times the explosive force thatexploded over Hiroshima in August 1945 Still, it is just propane.Right?

Suburban America believes in chemistry when it comes to theirpretty yards, colorful flowers, and heavily laden vegetable gardens

In just the care and feeding of their lawns, they rely on sprayedfertilizers, pesticides, selective herbicides, fogs for trees, and powdersfor annoying ants If you watch Joe Q public working with the likes

of these, often as not you will find just a bit of care included Servicecompanies warn you to keep your animals away from sprayed areasuntil dry Folks generally wear gloves and avoid spreading chemicals

on windy days Some go as far as to wear dust masks The point here

is that they think about it Why? What is the difference between thehazards of LPG and lawn care chemicals? They both are hazardousbut in different ways, and, generally speaking, both are accepted asacceptable risks by the public

2.1 KNOWLEDGE LEVEL

In this day and age, we are sensitive to the use, misuse, and abuse

of chemicals Situation-stained landscapes such as Love Canal andBhopal are at the near edge of our memories and, if not, there isalways a chemical release or Resource Conservation and Recovery Act(RCRA) violation or factory fire spewing noxious fumes somewhere

on the news With these constant reminders, we realize that, whilechemicals are necessary, they are also dangerous And since there hasnot been a recent, prominent example of a propane truck leveling acity, it is just assumed to be not as dangerous After all, it is justpropane, right?

To lay this issue solely at the feet of education is ing it First, this approach assumes that a well-informed public willperceive the risks as the experts do and that a low probability of

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16 CHAPTER 2 Risk Perception

an incident’s occurrence is enough to quantify the risk as ficant This approach, while mathematically valid, does not considerthe emotional component the general public includes when they weigh

insigni-in Teach them about a hazardous process, derive its accidents andinitiators, describe potential mitigations, and a definite chance existsthat you will just end up with hyperaware protestors If for no otherreason than they now can quantify the results, regardless of the factthat that particular set of results is considered highly unlikely in theview of engineers and scientists That is the power of emotion.Then there is the cognoscente—those same scientists and engi-neers mentioned earlier This “trust me” crowd can undermine allefforts an emergency management plan puts together with lackadaisi-cal commitment and faint praise Instead of objectively quantifyingthe issues and assessing the necessary response, these types enablethe denial and Pollyannaish attitude often adopted in the burgeoningmoments of an incident In comparison to all possible reactions, scien-tific apathy is probably the most dangerous Those smitten with it areoften the last to realize that the water has risen over their collectivechins and they do not know how to swim

If data cannot adequately focus on one’s perception then thosefactors that can are of some import They are at least a subset ofthe knowledge necessary to engage in successful emergency manage-ment (assuming successful emergency management requires a targetedrisk perception) Subjectively speaking, the greatest influence on alayman’s risk perception is probably experience It is common formankind to live by the ideals, ideas, and rules of thumbs that are eitherestablished or rooted in some past learning obtained solely through theact of living or listening to those who lived before you Unscientific?Certainly But, over time, the impact of experience has more historythan even science (witness the power of lore throughout time), so it

is worth listening to

Ideals (or principles, if you had rather) are beliefs stemming fromsome personal philosophy They represent good versus bad and rightversus wrong, binaries and shades of gray that we choose to use toguide our lives One’s ideals are founded from so many avenues thattheir mapping would look like a spider web There is parental influ-ence, religious posturing, peer pressure, social paradigm, economicstratification, and a thousand other variables to contend with Luckily,for the analysts, it is also a social paradigm that most folks establish

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