Plaudits Come Easily From People Who've Been in Air Bag Crashes ...

2-11HSStatus Report, VOl. 28, No. J I, October 9, 1993Compari8oos by Impact Directlon: F6rthree years, Institute researchers havebeen evaluating air bag effectiveness bycomparing driver deaths in crashes for twogroups Qf cars, these with lap/shoulderbelts plus air bags and similar cars withbelts only. Because air bags are designed towork in front and front-angJe crashes (principalpoint of impact from 10 to 2 o'clock,given 12 o'clock as the center front of a vehicle),the proportion of driver deaths inuch crashes should be lower with air bagscompared with belts only, This would betrue if the air bags are saving lives.In fa,ct, the proportion of deaths is lowerwith air bags. Based on new studies ofabout 18,000 driver crash deaths during1985-92, researchers find 24 percent fewerdeaths than expected in front and frontanglecrashes of air bag-equipped ears. Inall kinds of crashes, the death reduction is16 percent - a saving that's over andabove the lives already being saved by thebelts used in cars with air bags.Analyzing these results according toreported belt use, researchers further estimate,21 percent air bag effectiveness infrontal crashes for people using belts and23 percent effectiveness without belts.But there's a caveat because the informationon belt use in crashes, even fatalone~, isn't totally reliable. This limitationshould balloted when assessing the 21and 23 percent effectiveness estimates.Analysis by direction of impact alsosuggests. that air bags are most effectivein the largest automobiles. Tn front andfront-angle crashes, the, reduction in driverdeaths is 35 percent in large cars. It's 17percent in midsize cars and 26 percentin small cars.Comparisons by Registered Vehicle:The growing database on air bag crashesallows Institute researchers to begin com·paring driver deaths per 10,000 registeredvehicles in cars during their first year withair bags and their last year with belts only.To ensure that changes in the mix of carsin these two groups don't distort comparisonsbetween the groups, the results forcars with belts only are weighted to thesame mix of cars as the air bag r.esults.What researchers find is a driverdeath rate of 1.15 in all kinds of crashes ofcars with belts only compared with a rateof 0.96 in cars with bags plus belts - a 16percent reduction. The reduction is 23pement in front and front-angle crashes,and both results are very close to the effectivenessestimates derived from directionof impact analyses.Also similar are indications of greaterair bag effectiveness in large cars comparedwith smaller ones. lIt front andfront-angle crashes, researchers estimate30 percent air bag effectiveness in largecars, 23 percent in midsize cars, and 20perCent in small cars.~Various methods of estimating air bageffectiveness are beginning to yield consistentresults," notes Institute PresidentBrian 0' el11. But, he cautions, "eventhese new estimates can be expected tochange over time with the changing mix ofcars with air bags. They'll also change asbelt use continues to inch upward. Theoverwhelming contlusion at this time isthat air bags are saving many motorists."

llHS Status RefJ{)rt, VoL 28, No. I I, October 9, 1993-3Plaudits Come Easily From People Who'veBeen in Air Bag Crashes, Survey FindsAmong the biggest fans of air bag~ arepeople who've been in crashes in whichtheir air bags deployed. Ask if serious injurieswere prevented, and the overwhelminganSwer is yes. Ask motorists Uthey'reconc~med a out injuries from air bags ­no. Ask If they want an air bag· in theirnext car - another resounding yes.These are the major findfngs of the firstsystematic survey of motorists in air bagcrashes. Researchers surveyed 215 people,or every available driver who'd been''How well do youthink the air bag protectedyou from InJury?"76% A lot-100/0 Somewhat70/0 None-3% A little2% Increased InjUry2% Don't knowin an air bag deployment crash in NorthCarolina duting January-November 1991.Eighty-nine percent said they believethe atr lJag protected them from injury,and 76 percent said it protected them "alot." Only {our of the 215 motorists saidthey don't want an air bag in their ne«! car.Among the four drivers who said no toair bags, none suffered serious injury. Onewas bruised 1n thecneek area. Another wasbruised in the chest area. The third had ablister on the hand, and the fourth had anabrasion on the arm.Until the North Carolina survey wasconducted, thera had been no systematicstudy of the reported experiences of driversin air bag cra$hes. Driver perceptionsabout how air bags perform in crashes andabout possible injuries from the bags hadcome primarily frpm media reports andcomplaints to the National Highway TrafficSafety Administration.The survey addresses drivers' recollectionsof the crash, problems related to airbag inflation, belt use, injury type andseverity, medical treatm~t, assessment ofair bag performance, and whether the driverwO~ld want an air bag in the next car.Forty-four percent didn't recall anythingparticular about the deployment. Aboutone in five remembered something perceivedas a problem - dus~ odor, or noise.SAme drivers re~orted they sustained min@rinjuries, frequently bruises. Among''Would you wantan air bag In yournext car?"96% Yes- 2"oNo20/0 Don't knowthe specific injuries described by driverswere a "bit of abrasion plus cold feelliig,""~Ilght burn on the nose," and "sore. chestand arms. ~ Among all injuries, only 7 percentwere assessed by police as anythingmore than moderate."These responses put some of the recentnegative reports about air bags intoperspettive," ,gays fnstitute Senior VicePresident Allan F. Williams "Minor injuriesfrem inflating bags aren't uppermost in theminds, of those who've been in crashes."The survey was designed to find outwhat happens in air bag crashes. "Despiteminor problems such as ~brasions, drivershave aver.y favorable view," Williams adds.For a copy pf "Survey of Attitudes ofDrivers· in Air Bag Deployment Crashes" byD.W. Reinfurt, A,W Green, BJ. Campbell,and A.F. Williams, write to the Institute'sCommunicatrons Department, 1005 N.Glebe Rd., Arlington, VA 22201.campIThe Office ofat the NatioAdministrplaints, iThiscampbags.involvquentlylersbag vennitrogenbags, sompeople's arevents hsitloned.and theInvestigatirelativelyabout burnMore ththe camplalcoming in ipeople whotheir air bagshould haveplayed in a colUsion but didn't.When investlgators look Intcomplaints suchthese, they aimways find a m!8I_.-"about the cir;which air baIn particularknow airI i't Know thtt minimumspeair bags to deployin crashes. Automobile AirBags Aren'tDiffer a Lotin Terms ofConversely,volve:'i consumersbags deployed wStili other motorisment was violent.

I-IIH. tatus Repon, Vol.? '0, /1, October ,/993qui alent speed that' slower than 10mph. r it roa n inflate a a peed someo0 De e Bags- They De er a Lot iTerThe instant a fr ntal crash begins, thn ors in all air bag ystems begin to meaureImpact severity. If the crash is severeenough, th sensor signal inflators to fillthe bag with harml gas. The bag fill ina fraction of a econd to restrain occupanand quicld 'n deflating to furth rthe cushioning ed,'ot 0 ob iou are the differenceamOD air bag d igns - differences in deploymentthr hold. materials how thematerials are folded into modules, bag inflationpeed and pres ures, how gas Iv nted from the bags, and whether thebags are tethered or not. Such differencecan affect alr bag performance.When The Deplo: The most importantaspect of air bag d ign I making urethe bags depl ywhen they're needed in e­ri u frontal rash . ctuaJ deploymentthr holds var' orne hat from one alrbag design to an ther. but virtually aUterns are mad to deplo in crashes equivalentto hitting a oUd barrier at 10-12 mph.Mer des and BMW ir bag incorporatehigher deployment thresholds - more Uke15 mph - for people using belts.These are barrier-equiva/ent speeds,which are almost alway lower than thepeed a vehicle is going just before a crash.for example, a car going 30 mph that rearendanother car at a top slgn rna dissipatorne cr h ne through brakingJ t before impa and more as it pushthe truck car along th pa ement. ddi­Uonal energy would be absorbed by thetruck car bumper and rear-end, sobarrier~uivalent crash speed might fallbelow what's necessary for alr bag deploymnt. This would be true even though thepeed just before Impact was 30 mph.In real crash I which reflect a varietyf impact type. air bag deploymentpeeds vary. bag rna inflate at abarrier­ensoAccordionFoldModified Accordionor Revene FoldikeDesignwhat faster than 12 mph. It depend nthecrash and th design and location of an airbag system's era h sensors.Crash SenIO • The number and location01 the sen or that signal air bags toinnate vary from model to model. 0 t systernsuse toto f ur electrome hanicaJsensors in a ehl Ie' front end. Th areeither balI-ln-tube or pring-mass types inwhicb the bailor mass moves in proportionto crash severity. When an impa t isFolde ere en ugh. an electri al c ntact ignalthe ba to Inflate.Afew alr bag systems use a in Ie crashensor, u ually an electronic one that incorporatean accelerometer to mea UTecTash severity. Electronic en ors areplanned for more cars in the future, in partbecause they can provide more informationabout crash severity than electromecbanial on can. The latter can onlsignal that a crash is above or belo a deploymentthreshold.ercedes and B hav adjusted deploymnt thresholds to depend on whetherpeople are using belts (threshold are high-

OHS Status Report, Vol. , o. 11, October 9, 1993-5er If belts are buckled). But thi can causeonfusion when for example, a belted driveralone in a car is In a crash that's severeenough to deploy a bag for an unbelted occupantbut not severe enough to deploy abag for someone who's using a belt. Thepassenger bag could lnflate because, withlanyone on that ide. the belt wouldn'tbe buckled. At fhe same time, the belteddriver's air bag could still be In Its module.An obviOus solution would be a sensort detecl eat occupancy but, so far, thisn'l proven reliable enough. Air bag componentsand features must prove extra0rdinarilyreliable before they're Introduced.lnfIaton: The Inflatorsin today s airbags differ a lot. earlyall are pyrotechnic.meaning they burnsodium azide to producethe nitrogen thatinflates th bags. I·leman e designs areabout to be introducedthat use bothodium aZide andlored argon gas.Inflation speedand bag pressures arec ntroll d by theamount of sodiumazide and its precisefonnulation. Maximumdeployment speedvary widel from car model to car modelThe maximum speeds of air bags in some1990 models, {or example, range from 98mph to m re than 200 mph. This finding isfrom ational High ay Trame Safety Administrationresearch.But bag speeds and pressures in any givencar ar the same regardless of crashseverll - a performance limitation beauseair bags must lnflate rapidly to protectbelted as well as unbelted occupants inhigh-se~erity crashes while, in crashes oflower severity, very filSt inflation can meaninjuries when people contact bags in theearly stages of inflation. A1991 study fromthe University of ichigan, for example, indiales that the speeds at which deployingair bag contact occupants trongly influencethe likelihoOO of abrasions.Automakers take a number of approachesto this tradeoff between protecting peoplein severe crashes and reducing the riskof air bag-lnduced injuries in lower-speedcrashes. ch approaches involve differentbag speeds and pressures. They may alsoinvQlve air bag folding patterns and/ortethering to limit bag extension.Folding Patterns: The material fromwhidJ air bags are made, particularly thetexture, was once thought to affect the likelihoodof abrasions from deploying bags.Untetheredow researchers believe abrasion likelihoodrelates to the speeds at which theurfaces of inflating bags "slap" occupants.The University of Michigan research concludesthat bag speeds are strongly influencedby the folding patterns used to packbags into their modules. Avariety of s&­phisticated patterns are used (see illustrations,p.4). The effects of tethering are alsosignificant, the researchers report.TeIberiDg: The base of every air bag isanchored to its module, or container, andorne air bags have additional tethers inide.These were originally intended tocontrol the sbape. and size of an inflatedbag, not to prevent abrasions. It no a~pears that, by limiting bag extension. tetheringcan in fact, reduce abrasions.At fuJi deployment, tethered bags extend10-13 inch toward a driver. Untetheredbags extend Ifr20 inches. Tetheringthus makes it less likely that people willcontact air bags moving toward them.entJ: The gas that inflates air bagsmust be vented immediately so that occupantscan "ride down" crashes on their d~Hating bags. The gas is vented throughopenings located in the backs of the bagsor through porous bag fabric. In some airbag systems, these vent openings used tobe located such that occupants occasionallysustained mino!burns from the ventinggas, but this pro~!em has been substantiallyreduced by movingthe locations of airbag vent holes.hat I Ahead:With so many dillerencesamong air bagdesigns, it's natural towonder which onesare best and whichones will be in moreautomobiles of the hrture. All of the answersaren't known,but it's safe to saythat many manufacturerswiIlgo to a singleelectronic sensor to signal air bags toinflate. More inflators are likely to be hybridsthat combine pyrotechnic andstored gas technologies. Plus, there will bepyrotechnic inflators in future car thatuse alternatives to sodium azide.It's also likely that air bags in cars ofthe future will be Ksmarter." Their inflationcharacteristics will be tailored tocrash severity, belt use, and the proximityof oc upants to their air bags just beforedeployment. These changes should su~stantially reduce the adverse effects thatsometimes occur when air bags deploy incrashes of lower eventy. (See .. eriouInjuries, Deaths," p.9.)

6-IJHS. olU Report, Vol. 2, o. II, October 9, [993head-on crash with extensive occupantcompartment intrusion, the driver ufofered mostly minor upper bod injuries.There were major lower body injuri includinga fractured hip a ruptured bladderand a severe enough injury to h'right foot that it had to be amputThe driver of the other car.havean air bag, was killeddriver survived ~"i.Ciand safety beIt~.PIIotocaseflH. tatus Report, Vol. 2, o. JI, October 9. 1993-7Air bag are aving hundreds of liveseach year, and they'll save thousandsn they're In every passenger vehicled. But air bags don't save everyntal crash. No occupant reuld.n a two-Jane road nearexample, a 56-year-oldbag-equipped Forder line of a statecoming Mack truckleft sideair bag.Iy wast

IHIHS Status Report, Vol. 28, No. II, October 9, 1993Occupants with Inlurles Caused byAir Bags Alone by Injury SeverityType and Locatron 01 Occupant InJuriesCaused by Air Bags AloneI.Head!'=Neck Chest Other TotalAIS 1 270 Abrasion 11. 91 2 225AIS2 10 Bruise 35 31 44 4 114AIS3 0 CuI 34 0 15 0 49AIS4 0 Bum 7 0 30 1 38AISS 0 Fracture 2 0 2 0 4AIS6 0Strain/sprain 2 0 1 0 3Concussion 1 0 0 0 1Total 280Detachment 1 0 0 0 1Rupture 1 0 0 0 1Source: SpecIal NHTSA 1nY8stI. Totai 199 47 183 7 438gallons of aft bag dlIploymentaasMs..of Juty " 1993 Source: SpecIal NHTSA In~ iliaii' bag ctepIo,menI c:rathes as 01 July " 1993(cont'dlromp.l) bags in crashes 01 relativelylow severity. In these situations, it'spossible thai no injuries at all would haveoccurred without the air bag.Air bag-induced injuries happen whilethe bags are still inflating. People injuredthis way often aren't using belts, sothey've moved forward enough to contactthe air bag early in its inflation. Anotherproblem involves people who sit veryclose to the steering wheel. Either way,they contact the bag belore full inflation.This can lead to air bag-induced injuries.Determining whether minor injurieslike bruises and abrasions are caused byair bags is relatively easy. But, lor thesmaller number of more serious injuries,determining the cause is often more dim·cult. This is because other interior featuresof vehicles - the steering wheel, forexample - may be involved. Investigatorsoften cannot distinguish the contributionof the bag from that 01 the other features.NHTSA Investigallons: As of July I,1993, the National Highway Traffic SafetyAdministration (NHTSA) had completedinvestigations of more than 1,200 crashesof cars with air bags. Institute researchershave reviewed 273 of these cases - allthose in which researchers confirmed theinjuries were caused by air bags alone ­and found 280 occupants with 436 injuriesreportedly caused by the bags.Ninety-six percent of these injuries areclassified minor (AIS 1) and the other 4percent are moderate (AIS 2), according tothe Abbreviated Injury Scale. This scale isan anatomically based system that classifiesinjuries by body region on a 6-pointscale according to threat to life. Acode ofAlS I rellects minor injuries like cuts andbruises, and AlS 6 represents injuries thatare inevitably fatal.Among the 436 air bag-induced injuries,none is classified AlS 3 or worse.That is, none posed a serious threat tolife. It's important to note that more seriousair bag-related injuries have been reportedto NHTSA but, so far, researchershaven't determined that any of them werecaused by the bag alone. (See MSerious Injuries,Deaths," p.9.)Filty-two percent of the 436 injuriesNHTSA has identified are abrasions thattypically heal without scarring. Another 26percent are bruises. Only 49 cuts (11 percentof all 436 injuries) and 38 burns (9percent) are reported.Moderate (AtS 2) injuries include a majorabrasion to the neck and cheek sustainedby an unbelted driver, a bruisedchest on another unbelted driver, a bre;ken arm, and two concussions. One of theconcussions occurred in a very severecrash in which the driver suffered onlymoderate injuries.Eye Injuries: A 1992 study from theUniversity of Michigan's TransportationResearch Institute notes that, although airbag-induced eye injuries can occur, they'reuncommon. This is the finding of NHTSAinvestigations, too. Only 28 injuries amongthe 436 reportedly caused by air bags involveoccupants' eyes, and 89 percent ofthese are classified as minor. The other 11percent are moderate, and none are classifiedserious. Still, such injuries promptconcern simply because they involve pe0­ple's eyes and because they can have longtermconsequences.One of the eye injuries, classified as minoraccording to the AIS threat-to-lifescale, involved a 22-year-old man withblurred vision from a lacerated retina andsubsequent bleeding. His vision may bepermanently blurred. In three other cases,occupants have required surgery to repaireye problems including a cataract, a detachedretina, and a ruptured eyeball.Research indicates that air bag designchanges - especially changes in bag de·ployment speeds, folding patterns, or tethering- can reduce injuries when peoplecontact inflating bags. (See MAlI AutomobileAir Bags Aren't Alike - They Differ a Lot inTerms of Design," p.4.) Some such modificationshave already been instituted.More Data, SImUar Andlogs: In additionto NHTSA liles, Institute researchers

Type and Location of Occupant InjuriesCaused by Air Bags AloneAbrasionBruiseCutBurnFractureStrain/sprainConcussionDetachmentRuptureTotalHead!Neck/Face1163534722211200Chest1631ooooooo47UpperExtremity9144153021ooo183Other24o1ooooo7Total225114493843211437Correction: Atable in Status Report, Vol. 28, No. 11, p.8 contains two incorrect columnheadings. The correct headings are shown above. In addition, the number ofconcussion injuries was incorrectly listed as one. Two is correct, as shown above.

IlHS tatus Report, I.:J. O. 11. Odober9, 1993-9safety belts, like air bags, restrain peopleIn crashes. And belts, like bags, maycause some Injuries as they perform this restraintfunction. Belt injuries are mostly topeople's chests, abdomens. shoulders, ornecks, while air bags more often injurearms, hands, or faces.Study of National Accident SamplingSystem data for 1988-91 indicates that 52percent of belted and unbelted occupantsprotected by air bags in moderate and severefrontal crashes (velocity changegreater than 10 mph) sustained no InjUryfrom the restraint. This compares with 87percent of occupants protected in frontalcrashes by safety belts alone. Forty-fivepercent of those in air bag crashes. comparedwith 11 percent of those in crasheswith belts only, sustained minor injuries(AIS 1) from their restraints.Injuries from belts as well as bags can bereduced by proper positioning of occupants.Drivers should sit as far from the steeringwheel as is comtortabIe becaUse, even withasafety belt, they can move forward enoughto hit hard interior surfaces In serious ccash·85. A lap belt should be positioned low overan occupanfs hips, not abdomen. People incars w1\h air bags shou\d 10Uow \he sameseating acMce morder to mmimize \he possibility0' contact w\\h an inflating bag.100Percentage of Drivers with Injuriesfrom Air Bags and safely Belts8060Air BagSalety Belthave analyzed their own database fmore than 2,700 passenger vehjclecrashes in a e en-county area nearCharlottesville, Virginia. The e filescontain information on 74 crashes ofair bag-equipped cars, and the bagsdeployed in 40 of the 74 collisions.The findings are similar to those inthe I1fSA 6J . That is, minor abrasionsand brui es all AI 1) are theonly injuries produced by the air bagsalone. Th e injuries occurred in 10of the 40 deployment crashes, and noair baflnduced injury was classifiedas anything worse than minor.SerioOJ Injuries, Deaths: Whilenearly all injuries caused by air bagalone are thu minor, a few are serious.For example, the New EnglandJournal of fedicine reports that a 22­year-old woman suffered an atrialtear in a relatively minor crash of herair bag-equipped car. The injurwhich required surgery and 11 daysIn the hospital to treat. Is believed toha: e resulted from contactwith an inflatingbag. The physicians reportingthe case noted that, in orne circumstances."the velocity 01 air bags ...may be sufficient to rupture the rightatrium, since it is one ot the thinnestvascular structures in the thorax."HT Ais investigating reports 01other serious air bag injuri • inclu~ing arm fractures. These investigationsare incomplete, and public detailsare sketchy in som cases. But itdoes appear that, In one instance, thearm 01 an older female driver wassplintered. Indications are that herarm was resting aero s the air bagmodule - that i . on the teeringwheel-when the bag deployed.Afew occupant deaths have evenbeen reported. for example, an unbeltedfemale was killed in a relativelylow-speed impact when her head andneck apparently were struck by an airbag early in its deployment. There'ssome. indication he was leaning overat the time in an attempt to restrain achild in the front passenger eatThree deaths involve short, elderlywomen who were thought to beated very 10 e to teering wheelswhen their air bags deployed in impactsof relatively low severity. Thein tigation that's been completedconcludes the fatality was caused byth combination of air bag and teerinheel loading. III this context. it'important to note that similar patternsof fatal injuries have been identiliedin low-severity rashes of carswithout air bags. Cee Status Report,Vol. 27, 0.4 March 14, 1992.)T 0 air bag-related deaths involvedrivers believed to have beenslumped over their teering wheels,becau e of medical condition , beforecrashe . In these cases, th bagmay have contributed to the fatal injuriesbut are unlikely to have beenthe sole cause.Two pa enger death ha e involvedchildren standing or sitting inthe front seats. One- case occurred inItaly, and few details are available. Inthe other case, a six·~ear-o\d thUdwho asn t in a sale\)' belt or childrestraint was reportedly thrown forward,into the dashboard, when thedriver braked before the crash. Thecollision into the rear oj another carwasn't severe, but the inflating pasenger-sideair bag may have propelledthe child into fatal contactwith the vehicle's rear-view mirrorand roof. This case is still under investigationat NHTSA.uch instances of deaths involvingair bags are rare compared with thelives being saved and injuries prevented.til\, all cases are being studied indetail to better understand the injurymechanisms. Then more advanced airbag terns can be developed for thefuture. (See "What's Ahead,' p.5.)

01. 28 o. 11 October 9, 1993pecial Iss eREPORTtOOS (lrth Glelx' RoadArlington, V 222111(103) ~47·1500 "'AX (70.1)247.1678Director 01 Public lIoilslEditor: Arme r1emlngWriter: Marla Kaufmann, Kim Llnellst r,and lalOIl J. Ra mu enEditorial As.~lstant: ' rl oe HughesIt Dir t Sheila Ja ksonDes gn Prod Ion: Joyc ThompsonISSN 0018-988X