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1、Chapter9Health HazardAssessment9.1INTRODUCTIONThe health hazard assessment (HHA) is an analysis technique for evaluating thehuman health aspects of a systems design. These aspects include considerations forergonomics,noise,vibration,temperature,chemicals,hazardousmaterials,andsoforth.Theintentistoid
2、entifyhumanhealthhazardsduringdesignandeliminatethemthroughdesign features. If health hazards cannot be eliminated, then protective measures mustbe used to reduce the associated risk to an acceptable level. Health hazards must beconsidered during manufacture, operation, test, maintenance, and dispos
3、al.On the surface, the HHA appears to be very similar in nature to the operating andsupport hazard analysis (O&SHA), and the question often arises as to whether theyboth accomplish the same objectives. The O&SHA evaluates operator tasks andactivities for the identification of hazards, wherea
4、s the HHA focuses strictly onhuman health issues. There may occasionally be some overlap, but they eachserve different interests.9.2BACKGROUNDThis analysis technique falls under the health design hazard analysis type(HD-HAT). The basic analysis types are described in Chapter 3. The HHA is per-formed
5、 over a period of time, continually being updated and enhanced as moredesign information becomes available.155Hazard Analysis Techniques for System Safety, by Clifton A. Ericson, IICopyright # 2005 John Wiley & Sons, Inc.The purpose of the HHA is to:1. Provide a design safety focus from the huma
6、n health viewpoint.2. Identify hazards directly affecting the human operator from a healthstandpoint.The intent of the HHA is to identify human health hazards and propose designchanges and/or protective measures to reduce the associated risk to an acceptablelevel. Human health hazards can be the res
7、ult of exposure to ergonomic stress,chemicals, physical stress, biological agents, hazardous materials, and the like. Aspreviously stated, phases where human operators can be exposed to health hazardsoccur during manufacture, operation, test, maintenance, and disposal of the system.The HHA is applic
8、able to analysis of all types of systems, equipment, and facili-ties that include human operators. The HHA evaluates operator health safety duringproduction, operation, maintenance, and disposal. The HHA technique, whenapplied to a given system by experienced safety personnel, should provide athorou
9、gh and comprehensive identification of the human health hazards that existin a given system. A basic understanding of hazard analysis theory is essential aswell as system safety concepts. Experience with the particular type of system ishelpful in generating a complete list of potential hazards. The
10、technique is uncom-plicated and easily learned. Standard, easily followed HHA worksheets and instruc-tions are provided in this chapter.The HHA concentrates on human health hazards during the production, test, andoperational phases of the system in order to eliminate or mitigate human healthhazards
11、through the system design. The HHA should be completed and systemrisk known prior to the conduct of any of the production or operational phases.Although some of the hazards identified through the HHA may have already beenidentified by the preliminary hazard list (PHL), preliminary hazard analysis(PH
12、A), or subsystem hazard analysis (SSHA) techniques, the HHA should not beomitted since it may catch hazards overlooked by these other analyses. Use ofthis technique by a system safety program (SSP) is highly recommended.9.3HISTORYThe HHA technique was established very early in the history of the sys
13、tem safetydiscipline. It was formally instituted and promulgated by the developers ofMIL-STD-882.9.4THEORYThe HHA focuses on the identification of potential human health hazards resultingfrom a system operators exposure to known human health hazard sources. In156HEALTH HAZARD ASSESSMENTgeneral terms
14、, these hazard sources stem from system tasks, processes, environ-ments, chemicals, and materials. Specific health hazards and their impact on thehuman are assessed during the HHA.Figure 9.1 shows an overview of the basic HHA process and summarizes theimportant relationships involved in the HHA proc
15、ess. This process consists of utiliz-ing both design information and known hazard information to identify hazards.Known hazardous elements and mishap lessons learned are compared to the systemdesign to determine if the design concept contains any of these potential hazardelements.The HHA process inv
16、olves:1. Identifying the human hazard sources agents (noise, radiation, heat stress, coldstress, etc.) involved with the system and its logistical support2. Determining the critical quantities or exposure levels involved, based on theuse, quantity, and type of substance/agent used3. Establishing des
17、ign mitigation methods to eliminate or reduce exposures toacceptable levels9.5METHODOLOGYTable 9.1 lists and describes the basic steps of the HHA process, which involvesperforming a detailed analysis of all potentially hazardous human health hazardsources.The thought process behind the HHA methodolo
18、gy is shown in Figure 9.2. Theidea supporting this process is that different kinds of design information are used tofacilitate human health hazard identification. The analysis begins with hazardsidentified from the PHL and PHA, which is the starting point for the HHA. Thenext step is to once again e
19、mploy the use of hazard checklists and undesired mishapchecklists. Of particular interest are hazard checklists dealing with human healthissues. Also, data on human limitations and regulatory requirements are used toidentify human health hazards. Hazards Mishaps Causal sources Human mishap risk Safe
20、ty requirements Design knowledge Health hazards PHL, PHA, SSHA,O&SHA (as available) Materials & processes 1. Identify system health hazard sources.2. Evaluate each source.3. Identify and evaluate hazard consequences.4. Document process. HHA ProcessOutputInputFigure 9.1HHA overview.9.5METHODO
21、LOGY157The HHA is strongly dependent upon the use of health hazard checklists. Hazardchecklists are generic lists of known hazardous items and potentially hazardousdesigns or situations and should not be considered complete or all-inclusive.Checklists are intended as a starting point to help trigger
22、 the analysts recognitionof potential hazard sources from past lessons learned.Typical health hazard checklist categories include:1. Ergonomics5. Chemicals2. Noise6. Biological3. Vibration7. Hazardous materials4. Temperature8. Physical stressWhen performing the HHA, the following factors should be g
23、iven consideration:1. Toxicity, quantity, and physical state of materials2. RoutineorplannedusesandreleasesofhazardousmaterialsorphysicalagentsTABLE 9.1HHA ProcessStepTaskDescription1Acquire designinformation.Acquire all of the design, operational, and manufacturingdata for the system.2Acquire healt
24、hhazardchecklists.Acquire checklists of known health hazard sources, suchas chemicals, materials, processes, etc. Also, acquirechecklists of known human limitations in the operation ofsystems, such as noise, vibration, heat, etc.3Acquireregulatoryinformation.Acquire all regulatory data and informati
25、on that areapplicable to human health hazards.4Identify healthhazardsources.Examine the system and identify all potentially hazardoushealth sources and processes within the system.Includequantity and location when possible. Utilize thechecklists.5Identify hazards.Identify and list potential hazards
26、created in the systemdesign resulting from the health hazard sources.6Identify safetybarriers.Identify design mitigation methods or barriers in the path ofthe health hazard source. Also, identify existing designfeatures to eliminate or mitigate the hazard.7Evaluate systemrisk.Identify the level of m
27、ishap risk presented to personnel,both with and without design controls in the systemdesign.8Recommendcorrectiveaction.Determine if the design controls present are adequate and,if not, recommend controls that should be added toreduce the mishap risk.9Track hazards.Transfer newly identified hazards i
28、nto the HTS. Update theHTS as hazards, hazard causal factors, and risk areidentified in the HHA.10Document HHA.Document the entire HHA process on the worksheets.Update for new information as necessary.158HEALTH HAZARD ASSESSMENT3. Accidental exposure potentials4. Hazardous waste generated5. Hazardou
29、s material handling, transfer, and transportation requirements6. Protective clothing/equipment needs7. Detection and measurement devices required to quantify exposure levels8. Number of personnel potentially at risk9. Design controls that could be used, such as isolation, enclosure, ventilation,nois
30、e or radiation barriers, and so forth10. Potential alternative materials to reduce the associated risk to users/operators11. The degree of personnel exposure to the health hazard12. System, facility, and personnel protective equipment design requirements(e.g., ventilation, noise attenuation, radiati
31、on barriers, etc.) to allow safeoperation and maintenance13. Hazardous material and long-term effects (such as potential for personneland environmental exposure, handling and disposal issues/requirements,protection/control measures, and life-cycle costs)14. Means for identifying and tracking informa
32、tion for each hazardous material15. Environmentalfactorsthateffectexposure(wind,temperature,humidity,etc.)When hazardous materials must be used in the system, the following consider-ations must be evaluated and documented: Hazards Mishaps Causal sources Risk Mitigation Methods SSRsHHAReportHHA Analy
33、sisHHA WorksheetsHardwareSystem Design ProcessesMaterialsChemicalsOperationsRegulatoryHuman Limitations Human Hazards Hazard SourcesFigure 9.2HHA methodology.9.5METHODOLOGY1591. Identify hazardous materials data:a. Nameb. Stock numberc. Affected system components and processesd. Quantity, characteri
34、stics, and concentrations of the materials in the systeme. Source documents relating to the materials2. Determine under which conditions the hazardous materials can pose a healththreat.3. Characterize material hazards and determine reference quantities and hazardratings (e.g., acute health, chronic
35、health, carcinogenic, contact, flammability,reactivity, and environmental hazards).4. Estimate the expected usage rate of each hazardous material.5. Recommend the disposition (disposal, recycle, etc.) of each hazardousmaterial identified.When feasible engineering designs are not available to reduce
36、hazards to accept-able levels, alternative protective measures must be specified (e.g., protectiveclothing, specific operation, or maintenance practices to reduce risk to an accept-able level). Identify potential nonhazardous or less hazardous alternatives tohazardous materials if they exist or prov
37、ide a justification why an alternative cannotbe used.9.6WORKSHEETThe HHA is a detailed hazard analysis utilizing structure and rigor. It is desirable toperform the HHA using a specialized worksheet. Although the format of the analysisworksheet is not critical, typically, matrix or columnar-type work
38、sheets are used tohelp maintain focus and structure in the analysis. Sometimes a textual document lay-out worksheet is utilized. As a minimum, the following basic information is requiredfrom the HHA:1. Personnel health hazards2. Hazard effects (mishaps)3. Hazard causal factors (materials, processes,
39、 excessive exposures, etc.)4. Risk assessment (before and after design safety features are implemented)5. Derived safety requirements for eliminating or mitigating the hazards.The recommended HHA worksheet is shown in Figure 9.3. This particular HHAworksheet utilizes a columnar-type format and has b
40、een proven to be effective inmany applications. The worksheet can be modified as found necessary by the SSP.160HEALTH HAZARD ASSESSMENTThe information required under each column entry of the worksheet is describedbelow:1. SystemThis column identifies the system under analysis.2. SubsystemThis column
41、 identifies the subsystem under analysis.3. OperationThis column identifies the operation under analysis.4. ModeThis column identifies the system mode under analysis.5. AnalystThis column identifies the name of the HHA analyst.6. DateThis column identifies the date of the analysis.7. Hazard TypeThis
42、 column identifies the type of human health concernbeing analyzed, such as vibration, noise, thermal, chemical, and so forth.8. Hazard No.This column identifies the number assigned to the identifiedhazard in the HHA (e.g., HHA-1, HHA-2, etc.). This is for future referenceto the particular hazard sou
43、rce and may be used, for example, in the hazardaction record (HAR) and the hazard tracking system (HTS).9. HazardThis column identifies the particular human health hazard. Itshould describe the hazard source, mechanism, and outcome. The specificsystem mode or phase of concern should also be identifi
44、ed.10. CauseThis column identifies conditions, events, or faults that could causethe hazard to exist and the events that can trigger the hazardous elements tobecome a mishap or accident.11. Effect/MishapThis column identifies the effect and consequences of thehazard, should it occur. Generally the w
45、orst-case result is the stated effect.12. Initial Mishap Risk Index (IMRI)This column provides a qualitativemeasure of mishap risk for the potential effect of the identified hazard,System:Subsystem:Operation:Mode:Health Hazard AssessmentAnalyst:Date:HazardTypeNo.HazardCausesEffectsIMRIRecommendedAct
46、ionFMRI Comments Status15423616910111315121478Figure 9.3Recommended HHA worksheet.9.6WORKSHEET161given that no mitigation techniques are applied to the hazard. Risk measuresare a combination of mishap severity and probability, and the recommendedvalues are shown below:SeverityProbability1. Catastrop
47、hicA. Frequent2. CriticalB. Probable3. MarginalC. Occasional4. NegligibleD. RemoteE. Improbable13. Recommended ActionThis column establishes recommended preventivemeasures to eliminate or control identified hazards. Safety requirements inthis situation generally involve the addition of one or more b
48、arriers tokeep the energy source away from the target. The preferred order of pre-cedence for design safety requirements is as shown below:Order of Precedence1. Eliminate hazard through design selection.2. Control hazard through design methods.3. Control hazard through safety devices.4. Control haza
49、rd through warning devices.5. Control hazard through procedures and training.14. Final Mishap Risk Index (FMRI)This column provides a qualitativemeasure of mishap risk significance for the potential effect of the identifiedhazard, given that mitigation techniques and safety requirements are appliedt
50、o the hazard. The same values used in column 12 are also used here.15. CommentsThis column provides a place to record useful inform-ation regarding the hazard or the analysis process that are not notedelsewhere.16. StatusThis column states the current status of the hazard, as eitherbeing open or closed. This follows th