Spring 2002 Missoula Technology and Development Center No. 5

0251-2815-MTDC

• Work/rest issues• Assignment length• Shift length• Fatigue counter-

measures

Health & Safety ReportWildland FirefighterWildland FirefighterWildland Firefighter

In this issue:

BackgroundThis report, the fifth in a series,reviews activities related to theMissoula Technology andDevelopment Center (MTDC)project on wildland firefighterhealth and safety. The projectfocuses on three main areas:

Work/rest issuesDevelopment of an objectiveapproach for thedetermination of work/reststandards and recommendedassignment lengths forcrews and overhead

Energy and nutritionImprovement of the energyintake, nutrition, andimmune function of wildlandfirefighters

Fitness and work capacityImplementation of workcapacity and medicalstandards, and improvementof the health, safety, andproductivity of firefighters

Work/RestIssuesThis report focuses on work/rest issues with specialattention to shift length, lengthof assignment, rest/sleepguidelines, and fatiguecountermeasures. Other work/rest issues include rest breaks,nutrition, hydration, and topicsrelated to performance andfatigue. Earlier reviews ofstudies in this area (Sharkey1980, Jukkala and Sharkey1989) indicated that a numberof factors influence workers’ability to maintain performancefor extended hours, days, orweeks of work. Physically fitand motivated workers are ableto perform for extended periods

when the work is meaningfuland the goal is worth attaining.In contrived or make-workstudies, performance declinesprecipitously with time. Studiesby MTDC show that workersperform above expectationswhen they are trained,motivated, and part of acohesive group, such as a type1 fire crew.

Work/rest issues areconfounded by economic,personal, and social concerns.Changes in assignment or shiftlength may affect firefighters’income. Family concerns alsoinfluence the desirability ofextended assignments. Whilethese issues are important tothe successful implementationof policy, they are outside thescope of this project.

University of Montana researcher Dr. Brent Ruby rises early to collect immunefunction and fatigue data in fire camp (see page 7).

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Featured Topic

Work and Fatigue inWildland FirefightingSteven Gaskill, Ph.D.

In 1980 and 1989 the MissoulaTechnology and DevelopmentCenter reviewed studies relatedto fatigue during extendedfirefighting operations. Sincethen, MTDC and others havecompleted additional studies.This report summarizes recentrecommendations fromlaboratory and field studies.

Definitions:

Fatigue—A sense oftiredness, either mental orphysical, brought on by stress(lack of sleep, physical work,nutritional inadequacies, ormental stresses). Fatiguefollowing work or sleepdeprivation is a normal stateand can be reversed withadequate recovery or rest.

Accumulated (Chronic)Fatigue—Fatigue from whichnormal rest does not producerecovery. Accumulated fatigueis often caused by extendedperiods of stress withinadequate recovery periods,resulting in decreasedproductivity, compromisedimmune function, andreduced alertness.

Fatigued workers performpoorly and behave carelessly,tolerate greater errors, andbecome inattentive. Theydisplay decreased motivation,

increased irritability anddepression, and low morale.Accumulated fatigue is morepersistent, producing a widerarray of effects onperformance, health, andmorale than ordinary fatigue.Accumulated fatigue requireslonger recovery periods thanordinary fatigue.

Energy Balanceand NutritionalDeficiencies

The total calories eaten byfirefighters need to match thetotal calories expended over anentire duty cycle and, ideally,over an entire season offirefighting. This balance cangenerally be monitored by bodyweight. However, the type offood that is eaten and the timethat the food is eaten may havea dramatic effect on the body’sability to recover from physicalstress.

Recommendations for Main-taining Energy Balance

• Body weight should bemaintained over the course ofa work assignment. Dailyfluctuations of 1 to 3 poundsare normal, due to water loss.Water loss should bereplenished before sleepingeach night. Loss of weightbecause of dehydration orloss of lean body mass is asign of fatigue and decreasedwork productivity. Sustainedweight losses of more than 1to 2 pounds per week havebeen shown to decreaseimmune function.

• The wildland firefighter’s dietshould include at least 60percent of calories fromcarbohydrates with less than30 percent of calories from

fats. The diet should includeabout 1.2 to 1.6 grams ofprotein for each kilogram (2.2pounds) of body weight. Thisrepresents 84 to 112 grams ofprotein per day for a 70-kilogram (154-pound)individual and 120 to 160grams of protein per day for a100-kilogram (220-pound)individual (an ounce is 28.4grams, about 70 percent oflean meat is protein). Thisrecommendation is based onstudies of individuals engagedin arduous aerobic ormuscular fitness training.

• Blood glucose and muscleglycogen (carbohydrate storedin the muscle) need to bemaintained or spared duringextended, arduous work tomaintain immune function,reduce upper respiratory tractinfections (URTI), andpromote work productivity,cognitive function, and safety.Supplemental foods and fluidscontaining carbohydrate needto be consumed regularlyduring the work day.

• Muscle glycogen levels need tobe restored between workshifts through normal dietand also by carbohydrateintake during the “window ofopportunity” when muscleglycogen is most easilyrestored. This window ofopportunity is within 15 to 45minutes after a work shift hasbeen completed. Individualsshould eat high-glycemic(quickly absorbed)carbohydrates during thewindow of opportunity. Crewsmight need to havesupplemental food availablebetween the end of the shiftand the next meal. This foodmay need to be available whencrews are being transported(or when they are waiting tobe transported) or during any

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• Work shifts should beshortened with reducedworkloads for 2 to 3 dayswhile workers acclimatize toheat stress.

• Acclimatization to altitudedepends on elevation, but ageneral guideline would be toreduce the duration andintensity of the work shift for1 day for each 1,000 feet inelevation above 6,000 feet.Individuals differ in theirresponse to environmentalstress. Crew leaders need towatch each crewmember forsigns of heat stress oraltitude-related problems.

Shift Length andSleep Duration

The recommendations of the1989 Wildland Firefighter Work/Rest Cycles Review are stillvalid. Crew leaders shouldadhere to the 2:1 work/restrequirement (for each 2 hoursof duty time—portal to portal—crewmembers should receive 1hour of rest or sleep). Longershift lengths require additionalsleep. These data are supportedby research for shift lengths upto 24 hours.

Recommendations on ShiftLength and Sleep Duration

• The current two-shift system(12 to 14 hours) is thepreferred alternative,providing that firefighters areprovided 1 hour of sleep orrest for every 2 hours worked.

• Most rested individuals cantolerate up to a 24-hour workshift without substantial lossof cognitive or physicalperformance, so long asadequate recovery is givenbetween shifts.

• Long work shifts (such asshifts over 20 hours) mayimpair recovery of theimmune system (seeResearch, page 7).

• Cognitive function is bestmaintained if the task isinteresting or demanding.Changing tasks improvesperformance during a longshift.

• Crew leaders need to beespecially careful that theyget enough rest. Long shiftsand lack of sleep impaircognitive function morequickly than they impairphysical productivity.

Assignment Length

Many studies of extendedoperations have beenconducted during militarytraining exercises. Wildlandfirefighters worked 21-dayassignments until the 2000 fireseason. Athletes performprolonged strenuous activitiesfor periods of up to 21 days(such as during the Tour deFrance bicycle race). Researchstudies and real-worldexperience agree that workersor athletes with adequatefitness, nutrition, motivation,and rest can maintainperformance for as long as 21days (for more on assignmentlength see Risk Management,page 10).

Recovery BetweenAssignments

A large number of factors needto be evaluated to meet the goalof having crewmembers andleaders begin an assignment in

situation when they will notreceive a meal within 45minutes after they havefinished their work shift.

• Crewmembers must maintainhydration at the beginning ofand during the work shift.Crew leaders need to watchfor crewmembers who maynot be carrying or consumingenough water, especially whencrews are working in hot, dryconditions.

EnvironmentalStresses

Environmental stresses add tothe total stress of a wildlandfirefighter’s duties and shouldbe considered when crewleaders evaluate situations thatmay increase accumulatedfatigue. Increases in altitude,heat, humidity, and smokeincrease the risk of fatigue. Inaddition, rough, steep terrainand dangers such as rollingrocks and snags increasephysical and mental stress,leading to a high level offatigue. More rest may berequired to recover adequatelybefore the next work shift whencrews are working in suchconditions.

Recommendations forAcclimatization to theEnvironment

• Acclimatization periods arenecessary for extended workat elevations higher than6,000 feet or when crews areworking in areas with hightemperature or humidity.Guidelines should bedeveloped to help managersdecide when acclimatizationperiods are necessary.

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a rested state. No data havebeen collected on wildlandfirefighters to evaluate whetherthe 2-day break betweenassignments is adequate, orwhether the crewmembers andleaders are able to recoveradequately during the 2-daybreak. A related question aboutrest and recovery is the state offatigue when crews begin anassignment. Do transport orother logistical factors result ina lack of sleep? A change intime zones or transport to anextreme environment (highaltitude or increased heat andhumidity) could increase thepotential for stress and fatigue.

Recommendations forEvaluating Fatigue at the Startof Arduous Work

• In all situations, the crewleaders should evaluate theneed for additional sleep andrest, or the need toacclimatize before beginningan arduous shift.

• Further research is needed toevaluate the effects of variousstressors on the ability torecover between assignments.

Guidelines forMonitoring andEnhancing Recoveryfrom AccumulatedFatigue

This section summarizes basicguidelines crew leaders can useto identify signs of accumulatedfatigue. Visible symptoms thatan individual is not recoveringadequately from daily stressesvary and depend on theindividual. Crew leaders shouldpay attention to individualswho complain about ormanifest two or more of thefollowing signs, especially

when the crew has beenexposed to situations that canincrease the risk ofaccumulated fatigue. Inaddition, the field testsdescribed below may provehelpful in situations whereleaders expect fatigue to beexcessive.

Many of the symptoms ofaccumulated fatigue, whenviewed independently of othersymptoms, may not indicateaccumulated fatigue. Whenmultiple symptoms occursimultaneously, crew leadersshould take appropriate actionsto reduce stress and enhancerecovery for the crewmemberswho are affected, or for theentire crew.

The symptoms of accumulatedfatigue include:

• Loss of body weight

• Decreased appetite

• An increase in resting heartrate

• An increase in submaximalheart rate at a fixed workload

• Perception that standardwork tasks are moredifficult

• Small (to large) losses incoordination and the abilityto do tasks requiringcoordination

• Muscle soreness that lastsmore than 24 hours

• Increase in upperrespiratory tract infectionssuch as colds or flu

• Decreased cognitivefunction

• Constipation or diarrhea

• A change in moods that mayinclude irritability ordecreased motivation ordesire

Crew leaders should know andapply measures to enhancerecovery from accumulatedfatigue. The basic measuresinclude:

• Increased sleep in anenvironment conducive tosleep

• Reduced duration andfrequency of physical work(possible change of duty thefollowing day)

• Adequate supplementalnutrition and fluids duringand immediately afterphysical work

• A high carbohydrate diet

• Monitoring the individualsfor recovery

Avoiding AccumulatedFatigue

All of the symptoms listedabove, except the resting andsubmaximal heart rates, appearonly after accumulated fatigueis evident. Of the easilymeasured field symptoms, onlythe heart rate measures seemto give some advance warningthat an individual isapproaching a state ofaccumulated fatigue. When acrew leader recognizessymptoms in crewmembers, theleader should take steps toenhance recovery.

When crews are placed inenvironments that mightincrease their risk foraccumulated fatigue, whencrews are starting anassignment in a fatigued state,or when increased mental andphysical stresses areanticipated, crew leaders maychoose to monitor individuals.This monitoring is in additionto attention paid to normalsymptoms of accumulatedstress. Monitoring

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crewmembers in the field mayrequire some equipment andtake a short period of time eachday. Current suggestionsinclude two tests that may alsobe used to evaluate whenworkers have recovered fromaccumulated fatigue.

Recommendations for Monitor-ing Accumulated Fatigue

• Compare daily body weight tobaseline weights. Duringstressful assignments, dailybody weight should berecorded when possible eachmorning before any food orfluids are consumed. Thisrequires that data bemaintained over the fireseason, including the baselineweight of individuals in arested state. Dailyfluctuations are expectedbased on dehydration andfluid loss that can be replacedduring meals. Consistentpatterns of weight losssuggest environments andwork that do not allowadequate recovery, or reflectinadequate nutritional intake.Generally, supplementalcarbohydrate intake andmaintenance of fluids shouldbe adequate to enhancerecovery for fit individuals.

• Monitor morning heart rateresponse to a standard 4-minute test (requiring 1minute of easy bench steppingand 3 minutes of rest) forearly signs of fatigue andimpaired recovery. Thisfatigue test was evaluatedduring the summer of 2001and compared to clinicalmeasurements of immunefunction. Athletes have usedmorning resting andsubmaximal heart rateresponses to monitorovertraining. The fatigue testmight be appropriate for

crews in “at-risk” situationsor when accumulated fatiguemight be expected. Using thistest requires taking baselinemeasurements andmaintaining data onindividuals over a period oftime to establish patterns (seeField Notes, page 12).

For these tests to be practicalin a fire camp, the medical tentwould need to include a scaleand an 8-inch bench. Anotheralternative would be for type 1crews to carry a scale andbench.

Additional FatigueCountermeasures

Fatigue countermeasures havebeen studied in militarypopulations and enduranceathletes. Although manyquestions remain to beanswered, work cycling is onearea of interest that may yieldpositive benefits for wildlandfirefighters.

Work Cycling—Athletes andcoaches have long understoodthat one of the most effectivemethods to counteractovertraining (accumulatedfatigue) is to vary the trainingin both intensity and durationso that days of arduous activityare interspersed with lessstressful days. This conceptallows athletes to avoid illnessand accumulated fatigue byscheduling time to recoverbetween hard work periods. Theresult is reduced time lost toillness, improved alertness,increased total work, andhigher productivity. The sameprinciples should apply towildland firefighters if stressfuldays are interspersed with lessstressful days. This might bedone for an entire crew or just

for certain individuals. Mostphysically fit individuals cansustain 1 to 2 days of veryarduous work, if they have aless stressful period (1 to 2days) for recovery. Recoverydays do not require inactivity,but do require a change of duty,generally to a duty with lesstotal stress. Little is knownabout duty cycling for wildlandfirefighters, but further studymight be beneficial.Recommendations for ways tovary the daily intensity andduration of arduous dutyshould be developed.

Fitness—Physical fitness isanother known factor inaccumulated fatigue in athletesand workers. When teammembers are asked to dosimilar training for extendedperiods, athletes who arephysically fit generally exhibitfewer symptoms ofaccumulated stress than doindividuals who are less fit.Research during the summer of2001 with two type 1 crewssuggested that the fit workersdid more work (both in absoluteterms and adjusted for bodyweight) and experienced lessfatigue.

Fitness Recommendationsfor Wildland Firefighters

• Aerobic and muscularendurance training before thefire season that is maintainedthroughout the season wouldbenefit firefighters whoroutinely work in situationsrequiring multiple extendedarduous work shifts withmoderate to high energyoutput. Fitness standards thatare higher than the pack test(walking 3 miles with a 45-pound pack in 45 minutes)should be considered. A

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Gaskill, S. 2002. Work and fatiguein wildland firefighting: a review ofthe literature. Missoula, MT:University of Montana HumanPerformance Laboratory. Copies ofthe complete review and a list ofreferences are available from BrianSharkey, bsharkey@fs.fed.us.

Dr. Steven Gaskill processes immunefunction samples as firefighters returnfrom the line.

fitness training manualshould be available to type 1crews.

• Individuals who have beenrelatively sedentary but whowish to take the pack testshould begin a trainingprogram gradually and slowlybuild up to the work capacityrequired for a wildlandfirefighter. The pack testshould be considered aminimum fitness require-ment. Individuals who will beworking on the fireline shouldbe encouraged to improvetheir aerobic (endurance) andmuscular fitness.

• The onset of fatigue as aresult of work depends on theindividual and is related tomany factors. Methods tomonitor fatigue within firecrews need to be developed todetermine when individuals orentire crews need time torecover.

Related Topics

Caffeine and other ergogenic(performance-enhancing)supplements may provebeneficial in some extendedoperations involving arduouswork. Studies of athletes haveshown that caffeine canincrease the utilization of fatduring extended moderatework, sparing carbohydrates. Inaddition, caffeine has beenshown to improve cognitivefunction during periods ofextended work. Unfortunately,caffeine is a diuretic and is notadvised during periods of heatexposure. A recent (2002)report by the U.S. Army hassuggested that new drugs thatpostpone physical and mentalfatigue may prove beneficial,

but their long-term effects arenot yet known. Commerciallyavailable supplementscontaining ephedra maycontribute to life-threateningconsequences during exertionand heat stress. It is beyond thescope of this report to considerthe growing list of ergogenicaids.

Other recommendations:

• Investigate drink or foodsupplements that could beused during extendedoperations to help maintainblood glucose.

• Compare supplements thatcontain energy andnutrients (such asantioxidants) and astimulant such as caffeine.A joint effort with the U.S.Army Research Institute ofEnvironmental Medicine ora similar group may bewarranted.

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Research

Immune Functionand Shift Length

This study compared thereduction in salivary IgA (sIgA)in response to a 14- or 21-hourwork shift. Salivary IgA is thefirst line of defense againstrespiratory infection. Seventeenwildland firefighters (15 menand 2 women) from twointeragency hotshot crews weretested. Subjects were studied inresponse to a short (13.9 ± 0.7hours) or a long (21.4 ± 0.3hours) work shift (table 1).Energy expenditure during awork shift was estimated usingthe method established by Heil(2001). Unstimulated saliva wascollected for 4 minutes beforework at 0530 and immediatelyafter a shift. The firefighters’salivary IgA secretion rate(micrograms per minute) wascalculated from an ELISA assayprocedure.

Results—The energyexpenditure during the longwork shift was significantlyhigher (p < 0.05, 4,101 ± 578kilocalories) compared to theshort work shift (3,322 ± 478kilocalories).

Salivary IgA was significantlydecreased after the work shiftbut had returned to the valuesrecorded before the shift by thefollowing morning in bothgroups. The 14-hour work shiftgroup showed a recovery insIgA (morning values at days 5

Salivary IgA Salivary IgA Salivary IgAShift length before shift after shift the next morning

(hours) (µg/minute) (µg/minute) (µg/minute)

13.9 ± 0.7 (n=6) 76.9 ± 23.1 14.0 ± 8.0* 82.4 ± 55.921.4 ± 0.3 (n=11) 54.1 ± 30.3 24.7 ± 26.5* 40.3 ± 29.0**

* p < 0.05 that the difference in values before and after the shift are due to chance.**p < 0.05 that the difference in values between the 13.9-hour shift and the 21.4-hour shiftare due to chance.

Figure 2—Changes in salivary IgA secretion rate in response to a single work shiftof 21.4 ± 0.3 hours (n = 11) followed by 5 days of 14 ± 0.7-hour shifts. Althoughsubjects demonstrate an acute recovery response, sIgA secretion rate is stillsuppressed 6 days after the 21-hour shift in comparison to the rate after a 14-hourwork shift.

Figure 1—Changes in salivary IgA in response to a single work shift of 13.9 ± 0.7hours (n = 6). The summary data for the fatigue index are also shown (heart rateresponse to a 1-minute step test). These data indicate adequate recovery after thesingle work shift.

0.00

10.00

20.00

30.00

40.00

50.00

60.00

70.00

Before shift 1 Before shift 2 After shift 6-dayafter shift

Next AM

Sal

ivar

y Ig

A s

ecre

tion

rat

e (µ

g/m

in)

and 6 were 85.8 ± 40.5 and 67.4± 32.0 micrograms per minute,respectively). In contrast, the21-hour work shift group

showed suppressed values forsIgA (27.3 ± 13.3 microgramsper minute) 6 days after theextended shift (figures 1 and 2).

PMAM AM0.00

10.00

20.00

30.00

40.00

50.00

60.00

70.00

80.00

90.00

100.00

300

320

340

360

380

Time Points

Tota

l H

R (

Fat

igu

e) I

ndex

Sal

ivar

y Ig

A s

ecre

tion

rat

e (µ

g/m

in)

Table 1—Shift length and salivary IgA.

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Table 2—Sustainable fitness (SF), energy expenditure (EE), and fatigue, represented by the change (∆) in heart rate (HR) index.

Conclusions—These dataindicate that the sIgA secretionrate is significantly depressedafter a single day of wildfiresuppression. The energyexpended during a work shift incombination with the shift’sduration may impair recoveryand increase the risk for upperrespiratory infection duringextended operations.

Ruby, B.; Gaskill, S.; Heil, D.;Sharkey, B.; Hansen, K.; Lankford,D., 2002. Changes in salivary IgAduring arduous wildfire suppressionrelative to work shift length.Medicine and Science in Sports andExercise. 34:s195 (study supportedby MTDC).

Fitness and Fatigue

This study investigated workand recovery rates in wildlandfirefighters with differing levelsof sustainable aerobic fitness.Eleven wildland firefightersfrom an interagency hotshotcrew served as subjects.Subjects were grouped by levelsof sustainable fitness asmeasured by oxygen intake atthe ventilatory threshold andstudied in response to workrates and recovery after singleor multiple arduous days ofwildland fire suppression(table 2). Work shift energyexpenditure was estimated

using the method establishedby Heil (2001). Recovery rateswere measured using asubmaximal heart rate (fatigue)index (page 12).

Work and recovery rates for 11wildland firefighters who hadlow or high sustainable fitness,energy expenditure and changein heart rate index werecompared (figure 3).

Conclusions—Wildlandfirefighters with highersustainable fitness (40 to 49milliliters per kilogram-minuteVO2) are able to do moreabsolute work and more workrelative to their body weightduring each day of a duty cyclecompared to less fit firefighters

(30 to 39 milliliters perkilogram-minute VO2). Fitindividuals recovered morequickly after multiple days ofarduous work despite higherenergy expenditures. Becausethe less fit group met orexceeded the minimal job-specific fitness requirementsfor wildland firefighting (thepack test), these data suggestthat the current fitnessrequirements may need review.Increased sustainable fitnessimproves work output andrecovery.

Gaskill, S.; Ruby, B.; Heil, D.; Sharkey,B.; Hansen, K.; Lankford, D. 2002.Fitness, work rates, and fatigue duringarduous wildfire suppression.Medicine and Science in Sports andExercise, 34:s195 (study supported byMTDC).

Daily Energy Expenditure (kcal) and Ventilatory Threshold (VT, L/min)

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

1 2 3 4 5 6 7 8 9Day into duty cycle

= Significant differences between groups

VT=2.45 L/min

VT=3.15 L/min **

**

***

*

Dail

y w

ork

(k

cal)

Ave

rage

Ave

rage

ener

gyen

ergy

expen

dit

ure

expen

dit

ure

SF(milliliters per EE EE ∆∆∆∆∆HR index ∆∆∆∆∆HR indexkilogram per (kilocalories (kilocalories per (1 arduous (3 arduous

minute) per day) day per kilogram) day) days)

Low SF 34.6±3.5 2735±199* 39.7±3.8* 5.1±18.0 37.3±14.7*High SF 43.7±3.9 3425±354 44.6±2.1 10.6±18.7 16.1±21.0

* p < 0.05 that the difference in values between the two groups is due to chance.

Figure 3—This graph shows the work (kilocalories per day) done by a hotshot crewover a 9-day period. The crew was divided into fit and less fit groups. The fit groupdid more work per day than the less fit group.

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Sleep Deprivation

This study compared the effectsof sleep loss with the effects ofalcohol intoxication onsubjects’ performance during ahand-eye coordination test.Forty subjects tracked a movingcircle on a computer screen atthirty-minute intervals after 28hours of sleep deprivation orafter ingesting 10 to 15 gramsof alcohol at 30-minuteintervals until their bloodalcohol level reached 0.10percent. During the first 12hours of sustained wakefulness(8 a.m. to 8 p.m.), trackingperformance improved 1 to 2percent above the starting level;performance then declined to alow of 6 percent below thestarting level. The decline

occurred from 8 p.m. to 8 a.m.,physiologically the lowestperiod for human performance.Performance rebounded to nearstarting levels during the finalhours of sleep deprivation.

After 24 hours of sustainedwakefulness, performance onthe tracking task decreased to alevel equivalent to theperformance deficit observed ata blood-alcohol concentrationof 0.10 percent, which meets orexceeds the definition ofintoxication in all States. Theauthors suggest that the“blood-alcohol equivalent” mayprovide policymakers with aneasily grasped index of therelative impairment associatedwith sleep loss.

Forest Service photo by Ben Croft

(Dawson, D.; Reid, K. 1997. Fatigue,alcohol, and performance impairment.Nature. 388: 235.)

Editor’s Note: While performance onthe simple tracking task declinedovernight, it rebounded in the morningafter 28 hours of sleep deprivation,confounding the relationship to bloodalcohol. The analogy to alcoholimpairment may make sense for pilotsor even bus drivers (where therelationship to tracking tasks holds),but it does not reflect cognitiveperformance or decisionmaking inwildland firefighting.

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RiskManagement

Assignment Length

Before the 2000 fire season, thestandard assignment forwildland firefighters was 21days. The shift to a 14-dayassignment was due, in part, toa comment in the WildlandFirefighter Safety AwarenessStudy (TriData 1998). In adiscussion of the causes offatigue, the report said:“Firefighter personnel oftenwork too many consecutivehours, on too many consecutivedays, and often on too manysuccessive fires.” The reportwent on to say that: “Data froma BIA [Bureau of Indian Affairs]study showed that the majorityof injuries occurred amongcrews during the third weeksince they had left their homebase” (page 5–57). The editor’sattempts to locate and reviewthe BIA study have not beensuccessful. So this major policyshift was influenced by a studythat has not been available forreview.

In a study of fatigue and stressamong firefighters andoverhead conducted during the2000 fire season, the 14-dayassignment policy was the“problem” most oftenmentioned by firefighters andmanagers. Many argued thatthey should be able to usejudgment to determine when toterminate an assignment. Crewleaders and overhead teampersonnel felt they were in thebest position to judge the

effectiveness of their respectivegroups. The 14-day policyshould be evaluated in severalareas, including: health, safety,and performance; logistics;social and family effects; andthe effects on the firefighter’smorale. The analysis shouldconsider single compared tomultiple assignments, crewtypes, overhead, andcontractors.

Health, Safety, andPerformance—Health issuescan be evaluated with medicalrecords and measures ofimmune function. Safety duringextended operations can beevaluated with an injurysurveillance system. Theliterature on physicalperformance in extendedoperations supports the abilityof fit and motivated workers toperform for prolonged periodswhen they receive adequate restand nutrition. A type 1 crewshould be able to complete a21-day assignment withoutadverse effects, while sometype 2 crews may lack thetraining to complete a 21-dayassignment without unduefatigue. When multipleassignments are involved,several options are possible:allow crew leaders to shortenthe assignment to adjust to thecrew condition and thedifficulty of assignment; and/ordevelop a schedule thatshortens the length ofassignments as the seasonprogresses.

Assignments longer than 14days may have a greaterphysical impact on firefightersthan on overhead personnel.

Logistical Issues—Travel,incident command teamoverlap, cooperator regulations,and other issues are affected bythe 14-day policy. Increased

travel increases the risk tohealth and safety. The periodwhen incident command teamsoverlap increases with shorterassignments. Some Stateagencies have regulations thatdiffer from Federal policies. The14-day policy increases theneed for additional firefightingpersonnel.

Social/Family Issues—Asidefrom health or performanceissues, the 14-day assignmentmay encourage moreparticipation by the “militia”(regular employees whovolunteer for fire duty). Manyemployees appreciate theopportunity to get home morefrequently.

Paycheck Issues—Payincentives that encouragefatigued firefighters to worklong shifts or assignmentsshould be eliminated. Policychanges must be revenueneutral if firefighters are tomaintain their morale.

Firefighters’ performancedepends on their level offitness, motivation, nutrition,previous assignments,acclimatization, hydration,immune function, and otherfactors. No single formula willaccount for the complexinteractions among thesefactors. One approach would beassignment limits (such as 21days for type 1 crews and 14days for type 2 crews) temperedby judgment and adjusted forconditions and back-to-backassignments. The impact offatigue during the 2000 seasonwas tempered by a change inthe mission, brought on by theimmensity of the task. Theintensity of the fires oftenprecluded direct attack, sofirefighters were more likely topace themselves. The taskbecame a marathon rather thana sprint.

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Field NotesFatigued workersperform poorly,behave carelessly,become inattentive,and make more errors.They displaydecreased motivation,increased irritability,and low morale. Crewleaders should watchfor behavior changesand other signs thatworkers are fatigued.

Fatigue tends to behigher at the midpointand toward the end ofa work shift.

Fatigue: Signs andCountermeasures

Fatigued workers performpoorly, behave carelessly,become inattentive, and makemore errors. They displaydecreased motivation,increased irritability, and lowmorale. Crew leaders shouldwatch for behavior changes andother signs that workers arefatigued.

Fatigue tends to be higher atthe midpoint and toward theend of a work shift. Accidentspeak during the last 2 hours ofa 10-hour day. Alertness beginsto decline from 1600 to 2300;after 2300, the likelihood offalling asleep increasesdramatically. Sleep-deprivedworkers may suffer from short,intermittent episodes of fatigue.These episodes arecharacterized by very brieflapses in the performance oftasks, during which details aremissed, accuracy is impaired,and performance is slowed.

Signs of Fatigue• Poor and careless

performance

• Greater tolerance for error

• More difficulty concen-trating and thinking clearly

• Inattention to minor butpotentially importantdetails

• Increased lapses ofattention

• Increased irritability

• Decreased motivation

• Slow reaction time

• Impaired communicationand cooperation,particularly when workingas a crew

• Complaints of headache,stomach, or otherproblems

• Feelings of depression

• Poor morale

• Loss of appetite

• Weight loss

While there is no substitute foradequate sleep, rest, or timeoff, crew leaders can employsome short-term counter-measures to minimize thehazards presented by fatiguedworkers.

Recommendations to MinimizeFatigue: Fatigue Counter-measures

• Ensure that workers areadequately rested before theybegin a work shift.

• Slow the work pace to amoderate level on physicallydemanding tasks.

• Provide periodic rest breaks toallow physical and mentalrecovery.

• Alternate between heavy andlight tasks.

• Change assignments toprevent boredom.

• Provide breaks, naps, or timeoff after tasks have beencompleted.

• Provide nutritional foodbefore, during, and after work.

Recommendations forAssignment Length

• Establish broad guidelines forassignment length that areappropriate for the demandsof the tasks and are specificto the type of the crew.

• Develop work-capacitystandards to reflect thecurrent capacity andperformance expectations fortype 1 crews.

• Review the work-capacity testrequirements for all personnelto ensure that each individualis taking the appropriate test.

• During extended operations,when multiple assignmentsare necessary during a fireseason, empower crew leadersto use their judgment indetermining when toterminate an assignment.

• Provide training to help crewand team leaders recognizethe signs and symptoms offatigue and to manage crewsduring extended operations(see Field Notes this page).

• Eliminate pay incentives thatcause firefighters to continueworking when they areseverely fatigued.

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• Provide energy supplementsbetween meals.

• Provide fluid energysupplementation and makecertain it is used.

• Ensure that workers maintaingood personal hygiene.

• Maintain high standards ofphysical fitness and workcapacity.

Adapted from Countermeasure. 1998.Army Group Risk Management Pub-lication (19 : 6) and material publishedin the U.S. Army Crew EnduranceLeaders Guide. 1997.

24-Hour Shifts

Australian bush firefightersmay employ a 24-hour shift onthe first day of a 7-dayassignment. They work 24hours (including travel time),followed by 8 hours of rest.They may work up to 16 hoursa day for the rest of the 7-dayassignment. According to SueEllis, health and fitnesscoordinator for NaturalResources and Environment inVictoria, she is not aware of areported incident (injury orfatality) that could be attributedto fatigue on the 24-hour workshift.

A 1989 MTDC report notes thatthe 24-hour work/rest cycleshould be considered amanagement option when the2:1 work/rest ratio cannot beprovided with the two-shiftsystem, or when transportation,logistical, or safety problemsexist. The report recommends12 hours of sleep after the 24-hour shift. Furthermore, thereport recommends a 12-hourrest period preceding prolongedwork or expected sleep loss.For either shift alternative, thereport stated that incident

command and dispatchingorganizations should pay moreattention to crew sleep/restbefore they are assigned to thefirst shift on a fire. (Jukkala,A.; Sharkey, B. 1989. A study ofwildland firefighting work/restcycles. Tech. Rep. 8951–2235–MTDC. Missoula, MT: U.S.Department of Agriculture,Forest Service, MissoulaTechnology and DevelopmentCenter.)

Fatigue Index

This fatigue test can be used toevaluate recovery from physicalwork. The test requires thatindividuals establish normalvalues over a period of a fewdays when they are well rested.These values can be comparedto values on mornings followingdays of hard physical work toevaluate recovery. Studies showthat fatigue (as indicated by thefatigue test) is related todecreased performance andimmune function. It is easiestto take this test using a heartrate monitor, but manual heartrates can be taken using aradial artery (wrist) or carotidartery (neck) pulse. The test isgenerally done in the morning,before eating breakfast ordrinking stimulants, such ascoffee.

Tools Needed

◆ Heart rate monitor(suggested, but notrequired)

◆ Stopwatch for timing

◆ Metronome (set for 120beats per minute) or a largeclock with sweep hands andclear second markings

◆ 8-inch (20-centimeter)-highbench

Procedure

After getting up in the morning,before eating breakfast ordrinking stimulants, such ascoffee:

1. Sit quietly in a chair for 3to 5 minutes until your heartrate is stable.

▼Record resting heart ratefrom the monitor, or takeyour resting pulse at thewrist or neck for 10seconds and multiply thenumber of heartbeats bysix to get the rate perminute.

2. Start a watch and beginstepping.

▼Step up with one foot andthen up with the next (soboth feet are on bench).Step one foot downfollowed by the other soboth feet are on theground. This is done atthe cadence of 120 beatsper minute so that eachbeat represents a step. Ifan individual is watching asweep hand on a clock,the two steps to step uponto the bench or stairshould take 1 second andthe two steps to step downshould take 1 second. Theentire sequence ofstepping both feet ontothe bench and both feetback to the ground shouldtake 2 seconds.

3. After exactly 1 minute ofstepping, stop. Whilestanding:

▼Note exercise heart ratefrom the monitor or takethe exercise pulse at yourwrist or neck, and sitdown immediately.

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4. Sit quietly, focusing onrelaxation.

▼At 30 seconds afterstopping exercise, takeyour heart rate.

▼At 60 seconds afterstopping exercise, takeyour heart rate.

5. Record all heart rates:

▼Resting heart rate________

▼Exercise heart rate_______

▼30-second recovery heart rate_______

▼60-second recovery heart rate_______

▼Fatigue index sum of heart rates_______

Experience with athletes anddata from the 2001 fire seasonwould suggest that anindividual with an increase inthe fatigue index of 30 to 40beats probably needs a day withreduced work stress. When themorning fatigue index is morethan 40 above the restingaverage, individuals should beassigned duties with low stressuntil they are recovered towithin 30 beats of restedvalues.

The fatigue test was developed bySteven Gaskill, Ph.D., University ofMontana Human Performance Lab-oratory. For more information contact:sgaskill@selway.umt.edu.

Increase in fatigue index (sum of heart rates)

0 to 30 above rested –Not generally a concern

30 to 40 above rested –Slightly increased risk

40 to 50 above rested –Increased risk

More than 50 above rested –High risk

Understanding theFatigue Index

The fatigue index is unique foreach individual and must becompared to that person’saverage index for several daysduring a rested condition.

The more elevated the dailyfatigue index from the restedaverage, the more likely theindividual is not recoveringfrom the prior day’s work andstress, and the more likely theindividual will be at risk fordepressed immune functionand upper respiratory trackinfections. The followingguidelines vary depending onthe individual.

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Additional single copies of this document may beordered from:

USDA Forest ServiceMissoula Technology and Development Center5785 West Broadway St.Missoula, MT 59808-9361Phone: 406–329–3978Fax: 406–329–3719E-mail: wo_mtdc_pubs@fs.fed.us

For additional technical information, contactBrian Sharkey at MTDC.

Phone: 406–329–3989Fax: 406–329–3719E-mail: bsharkey@fs.fed.us

Electronic copies of MTDC’s documents areavailable on the Forest Service’s FSWeb Intranet at:

http://fsweb.mtdc.wo.fs.fed.us

If you have comments,questions, or suggestions

about this report or project,send them to:

bsharkey@fs.fed.us.

Publications

Wildland Firefighter Health andSafety Report, Nos. 1 (0051-2825-MTDC), 2 (0051-2855-MTDC), 3 (0151-2817-MTDC)and 4 (0151-2840-MTDC) areavailable from MTDC.

Coming up. . .

The next Wildland FirefighterHealth and Safety Report in fall2002 will consider:

• Energy requirements

• Energy supplements

• Nutritional strategies

• Micronutrients

• Immune function

The Forest Service, United States Department of Agriculture(USDA), has developed this information for the guidance ofits employees, its contractors, and its cooperating Federaland State agencies, and is not responsible for the interpretationor use of this information by anyone except its own employees.The use of trade, firm, or corporation names in this documentis for the information and convenience of the reader, anddoes not constitute an endorsement by the Department of

any product or service to the exclusion of others that may besuitable. The U.S. Department of Agriculture (USDA) prohibitsdiscrimination in all its programs and activities on the basis ofrace, color, national origin, sex, religion, age, disability,political beliefs, sexual orientation, or marital or family status.(Not all prohibited bases apply to all programs.) Persons with

disabilities who require alternative means for communicationof program information (Braille, large print, audiotape, etc.)should contact USDA’s TARGET Center at (202) 720-2600(voice and TDD). To file a complaint of discrimination, writeUSDA, Director, Office of Civil Rights, Room 326-W, WhittenBuilding, 1400 Independence Avenue, SW, Washington,D.C. 20250–9410, or call (202) 720-5964 (voice and TDD).USDA is an equal opportunity provider and employer.