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OAR Box 1142 

Prepped by Ollie Stewart 

Document Number: 

29) IV-H-12 

Docket Number: 

A-87-11 

Printed 4/23/2008 10:21:22 AM Sheet 29 of 30 
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a57 /\-U'f-l\ 

US. Department 

crfTror.;podorion 

Nattooal Wghwoy 

Traffic Sof#fy 

Administration 

NOV 2 7 199! 

400 Seventh Street. S.w. 

wasnington. O.C 20590 

1 1 

Mr. William G. Rosenberg 

Assistant Administrator for 

Air and Radiation 

U.S. Environmental Protection Agency 

401 M street, SW 

Washington, DC 20460 

Dear Mr. Rosenberg: 

On November 13, 1991, the Administrator of the National 

Highway Traffic Safety Administration (NHTSA) responded to 

your letter of November 8, 1991, concerning technical 

documentation for conclusions in NHTSA's October 31, 1991, 

letter to the Environmental Protection Agency (EPA). In that 

November 13, 1991, letter, NHTSA advised EPA that responses 

to all docket comments on the NHTSA report, "An Assessment of 

the Safety of Onboard Refueling Vapor Recovery Systems," 

would be submitted to EPA. The NHTSA Administrator has asked 

me to provide this submission to EPA. 

Enclosed is NHTSA's technical evaluation of the public 

comments received dealing with the report. In addition, the 

evaluation responds to the issues raised by EPA in your 

letter. The majority of the comments received supported the 

findings and conclusions in the NHTSA report. These comments 

are summarized in the beginning of the evaluation. Comments 

addressing specific issues are reviewed in the evaluation 

under six general topical headings: 1) prototype vehicles, 

2) complexity, 3) vapor release during refueling, 4) fire 

risks posed by existing evaporative systems, 5) laboratory 

testing, and 6) miscellaneous issues. 

This technical evaluation reaffirms the NHTSA conclusions 

expressed in NHTSA's report and in the NHTSA Administrator's 

October 31, 1991, letter regarding the safety of onboard 

refueling vapor recovery systems. 

Sin 

William A. Bodnly 

Associate Administrator 

for Enforcement 

Enclosure 

SAFETY BELTS SAVE LIVES 

AUTO 3APETY HOTUNE • 

(800) *2<-9393 

Waan. O.C. Ar»a 368-0123 
I0U-2?T199 1 16'-07 FROM US DOT/NHTSA ODI TO 8374836 P.0 3 

REVIEW OF COMMENTS SUBMITTED TO EPA ON 

NHTSA'S REPORT "AN ASSESSMENT OF THE SAFETY 

OF ONBOARD REFUELING VAPOR RECOVERY SYSTEMS" 

The vast majority of the comments at the public meeting, as well as those 

submitted to the rulemaking docket, strongly endorsed NHTSA's Report, "An 

Assessment of the Safety of Onboard Refueling Vapor Recovery Systems," 

hereafter identified as NHTSA's report. 

The Kator Vehicle Manufacturers' Association (MVMA) characterized the 

report as a thorough assessment of the safety of ORVR systems. MVMA 

further stated that the report was thorough and well documented, and that 

no coventor at the public meeting could undermine the .report's "sound and 

well documented conclusions." General Motors described NHTSA's report as 

comprehensive, thorough and well documented and stated that the findings 

in the report are conclusive and definitive. 

Chryslar supported NHTSA's report and stated that the report confirms 

Chrysler's continuing concern that ORVR systems unreasonably increase the 

risk to public safety. Toyota supported the conclusions in the NHTSA 

report. Nissan indicated that the NHTSA report raised legitimate safety 

related concerns regarding ORVR systems. Further, Nissan stated that, as 

indicated in the NHTSA report, ORVR would increase the risk of vehicle 

fires. Ford Motor Company supports the NHTSA report and the conclusion in 

the report that ORVR systems increase safety risk. 

The Insurance Institute for Highway Safety (IIHS), a nonprofit research 

and communication organization that identifies and develops ways to reduce 

motor vehicle crashes, concurs with the findings of the NHTSA report. 

IIHS states that NHTSA's report confirms ORVR systems pose an increased 

and unreasonable risk to motor vehicle safety. The National 

Transportation Safety Board, an independent agency concerned with 

transportation safety, stated that the NHTSA report, which concluded an 

increase in fire risks associated with ORVR systems, was consistent with 

the Board's position. The American Coalition for Traffic Safety stated 

that the NHTSA report convincingly demonstrates the increased safety risk 

associated with ORVR systems. 

The following analysis is directed at the comments, provided by the 

American Petroleum Institute (API), as well as other comments and issues 

related to onboard safety. The analyses are under six general topics; 1) 

prototype vehicles, Z) complexity, 3) vapor release during refueling, 4) 

fire risks posed by existing evaporative systems, 5) NHTSA's laboratory 

testing at the Vehicle Research and Test Center, and 6) miscellaneous 

comments to the NHTSA report. 

1. Prototype Vehicles 

API noted that at least three auto manufacturers have built experimental 

vehicles with ORVR prototype systems capable of passing FMVSS No. 301 

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test:;, NHTSA's safety standard fbr establishing maximum allowable liquid 

fuel leakage in laboratory crash tests. API states that a thorough and 

objcrtive NHTSA analysis would have included some discussion about this 

fact. 

First, API's assertion that NHTSA did not include discussion of these data 

1s erroneous. In NHTSA's report, a summary of FMVSS No. 301 testing is 

included on pages 25-26. These data demonstrate that the manufacturers' 

reported results of FMVSS testing Involve many "failures," i.e., the test 

vehicles did not meet the performance requirements of FMVSS No. 301. An 

exairyle, as indicated in its response to a NHTSA questionnaire (Appendix V 

of NMTSA's report), was Ford's reported tests on five paisenger cars that 

did not comply with the fuel leakage requirements*of FMYSS No. 301. 

Perhaps more important, however, 1s that even if compliance with FMVSS 

No. 201'were assured, this would not significantly reduce NHTSA's safety 

concerns. FMVSS No. 301 establishes performance requirements concerning 

liquid fuel leakage only. Thus, compliance with FMVSS No. 301 would not 

ensure protection against vapor leakage or component integrity. The fact 

that manufacturers are having difficulty complying with FMVSS No. 301 with 

ORVR-equipped prototypes heightens safety concerns. 

Asid from the concerns mentioned above, compliance with FMYSS does not, 

by its very nature, protect the public from all safety risks. Design, 

manufacturing, maintenance and durability defects arise in many 

performance areas not contemplated by FMVSSs or addressed by FMVSS 

performance requirements. Indeed, NHTSA has investigated and obtained 

recalls to remedy many fuel/exhaust system related defects, even though 

the vehicles complied with FMVSS No. 301 when new. Thus, safety defects 

can and do occur, despite a motor vehicle's successful compliance with 

FMVSr, No. 301. 

Another issue involves NHTSA's position regarding the utility of prototype 

vehicles. Clearly, ORVR prototypes have been developed that demonstrate 

performance in certain functional areas. The EPA Vehicle Based Simple 

System (VBSS) demonstrates that, under certain conditions, the ORVR system 

can perform the refueling vapor storage and purge functions. However, in 

order to demonstrate vapor control, storage, and purge throughout the 

entire spectrum of the motor vehicle operating environment, testing over a 

wide range of ambient temperatures and pressures is necessary. 

Neither the demonstration drive of the EPA VBSS vehicle by NHTSA during 

cool weather, nor the testing by EPA at temperatures of 80 degrees F 

during on road testing, or 95 degrees F 1n the laboratory setting, furnish 

sufficient information with which to make evaluations regarding either 

satisfactory or unsatisfactory safety performance. The driveability 

problems, such as stalling and hesitation, that have caused concerns over 

the past several years involving current production evaporative systems 

usually occur during operation 1n ambient temperatures ranging from 100 to 

115 degrees F. Neither EPA nor API have reported results of any tests 
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conducted at these higher temperatures. Adequate driveability in these 

environments is imperative to ensure that vehicles can meet performance 

requirements in real world operation. 

Once acceptable driveability performance is demonstrated, many other 

functional performance attributes must be assessed, such as emissions 

performance, maintainability, durability, and consumer acceptance. Each 

of these necessitates its own set of ORVR design characteristics, which 

frequently result in system design compromises in order to satisfactorily 

meet all functional requirements. Once a prototype that provides 

satisfactory functional performance 1n all areas is available, system 

design to assess safety concerns can be initiated. Merely demonstrating 

technical feasibility in one isolated functional area, such as 

driveability in moderate temperature climates, 1s insufficient to permit a 

conclusion about the safety of an ORVR system that could actually be used 

in the real world. 

The API onboard prototype, as reported in an SAE paper (SAE 90015), was 

similarly not subjected to a full series of tests to demonstrate complete 

functional performance. For example, the vehicles were not subjected to 

high ambient temperature driveability testing. Additionally, the FMVSS 

No. 301 rollover test was meaningless, as this test is designed to be 

performed only after the prescribed'FMVSS No. 301 crash test, which was 

not conducted. Thus, the SAE paper on this vehicle did not furnish any 

new information to diminish NHTSA's safety concerns. 

Information provided to NHTSA from the motor vehicle industry, as well as 

EPA and API data, suggest that many prototypes have been developed. None 

of the reported prototype vehicles perform satisfactorily in all 

functional areas and under all operating conditions. In addition to their 

own prototypes, auto manufacturers submitted information to this 

rulemaking proceeding which indicated the EPA system did not provide 

satisfactory performance from a safety standpoint. 

An issue raised in the rulemaking proceeding on ORVR is whether the ORVR 

rulemaking can or should force technology. NHTSA recognizes that, in some 

contexts, technology-forcing standards may be promulgated prior to the 

development of fully-developed prototypes. However, we believe that where 

critical safety concerns are evident, as here, one cannot be assured that 

safety will not be unduly compromised, even if functional prototypes were 

available for testing. 

Regarding technology forcing rulemaking, NHTSA has learned from experience 

that rulemaking is much more Ukely to be successful, particularly from a 

safety standpoint, the more fully developed the prototypes are at the time 

of rule promulgation. As pointed out by the Insurance Institute for 

Highway Safety (IIHS) in their October 22, 1991, submission to EPA Docket 

A-87-11, "Two decades of actual development had already resulted in air 

bag designs that were safe and reliable (at the time when rulemaking was 

promulgated)." In spite of this fact, a few problems did develop during 

initial production. 
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With regard to drawing a parallel between the risks and benefits of air 

bag jnd ORVR systems, IIHS, in agreeing with the NHTSA position, stated 

the following: 

"The major question remaining about air bags was not whether but how 

pany fatalities and injuries the system would prevent; even the most 

outrageous allegations of risks created by air bags were trivial 

compared to conservative estimates of their life saving benefits. In 

contrast, the major question about ORVR systems is not whether but how 

many additional fatalities and Injuries they will cause 1n crash 

fires." 

When NHTSA attempted to promulgate an antilock brake safety standard for 

heavy trucks, the standard was struck down by the Court of Appeals. The 

Court held that, without adequate confidence that technology existed to 

make a new mandated system as safe or Safer than current designs, NHTSA 

would be acting unreasonably. Thus, the existence of technology to 

achieve adequate performance across all functional areas, as well as 

safety, is critical to successful implementation of a rulemaking action. -

Clearly, if a rule requiring ORVR were to be promulgated, ORVR technology 

would evolve as manufacturers developed systems for mass production. 

However, the issue is not whether ORVR would force technology. The issue 

is whether the technology that would be forced would result in Increased 

safety risks to occupants of motor vehicles. On this issue, the record is 

clear and unambiguous. Implementation of ORVR, regardless of prototype 

development and technological evolution, will increase safety risks. ORVR 

systems will require additional components and must manage, store, and 

transport larger quantities of flammable fuel vapor. The safety risks 

involve potential system failures in both collision and non-collision 

events that are not present in existing vehicles and therefore represent 

an incremental increase above current safety risks. Thus, further 

technology development and operational successes or failures of prototype 

vehicles will not eliminate the fundamental safety issues associated with 

ORVR systems. 

Another technology-related issue is whether non-canister based 

technologies could provide the ORVR vapor control performance. NHTSA's 

safety position has been established from analyzing ORVR systems and vapor 

control methods that have been developed by EPA, API, and manufacturers. 

Other technologies, such as those employing bladder or diaphragm 

technology, have not been assessed because they are not available. 

2. Complexity 

One of NHTSA's principal conclusions was that the increased design 

complexity of ORVR systems will increase safety risk. Every ORVR design 

known to NHTSA indicates that ORVR systems will be much more complex than 

current evaporative systems. Additional components will necessarily be 

added to a vehicle in order to perform the vapor recovery function. Each 

of these components is susceptible to failure in normal operation as well 

as in accidents, and, should a failure occur, to associated safety risks. 

Complexity 1s always a consideration in motor vehicle safety. For 

example, NHTSA recognizes that the air bags in today's vehicles are 

complex systems and, in certain rare instances, this complexity may 
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adve ;ely affect safety performance. However, across the entire spectrum 

of mctor vehicle crashes, air bags will greatly improve motor vehicle 

safety. This is a fundamental distinction compared to ORVR that was not 

recognized by API and others who criticized NHTSA's analysis of the 

complexity issue. Directionally, ORVR can only degrade safety--it cannot 

improve it. 

The -mplexity risks associated with ORVR systems are identified in 

NHTSA's Report. The risks are presented by the following features of ORVR 

systems: 

The increase in the number of parts and connections will make ORVR 

systems more vulnerable to failure in collisions and in normal use. 

r;me ORVR components, such as filler pipe nozzle sealing devices and 

apor vent valves, will need to be placed in areas of potential 

oilision damage, adding to the likelihood of fuel and vapor release 

=n collisions. These sealing devices and valves are necessary, since 

tasting has shown that simpler systems cannot perform adequately. 

Many ORVR components will be larger than evaporative system components 

and therefore more difficult to locate in areas less likely to sustain 

damage in collisions. 

The larger ORVR components, particularly during operation in high 

ambient temperatures, will carry much larger inventories of fuel vapor 

than current evaporative systems, Increasing the likelihood of fires 

if a release of this vapor should occur in the presence of an ignition 

source. 

NHTSA considers these risks to be inherent. We believe that no amount of 

product development or engineering and quality control measures would 

fully alleviate these risks, regardless of lead time. 

Commentors referenced a 1988 Battelle study, "Fuel System Comparative Risk 

Assessment." API cited the study as a basis to claim that there was not a 

necessary relationship between complexity and risk for onboard systems. 

NHTSA disagrees with the methodology and conclusions in the Battelle 

study. 

The Battelle study examined 10 vehicle fuel system configurations: 6 

representing existing evaporative emission control systems and 4 

representing proposed designs, of ORVR systems. All 10 of the systems were 

selected by EPA and provided to Battelle. 

The methodology employed by Battelle is known as failure modes, effects 

and criticality analysis (FMECA). This is a subjective process in which 

the basic approach is to determine failure risk. The three principal 

steps in this analysis are 1) determination of hazard probability, 2) 

selection of leakage rate, and 3) the assessment of proximity to ignition 

source. 

The Battelle Hazard Probabilities were determined utilizing qualitative 

and subjective assessments of hazard risk, ranging from "improbable" to 

"frequent." Battelle then further applied these subjectively to 

individual components of the evaporative and ORVR systems selected by EPA 
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for .ialysis. This concept is inappropriate because the selected ORVR 

systems were not typical of systems that would go onto production 

vehicles, nor were the evaporative systems of the six evaporative vehicles 

representative of current vehicles. Battelle did not take into account 

the fact that ORVR systems will have numerous additional and larger 

components, longer and larger diameter hoses, and many additional 

connections, nor did Battelle consider the functional hazards possible 

with either system. 

Leakage rates were established in different ounce per minute categories. 

The largest category was the FMVSS No. 301 limit of 1 ounce/minute, and is 

a liquid flow rate measured after a crash. The leakage fate does not 

recognize high vapor flow rates possible In a crash, the his!i_flow--£ates 

durir.g a refueling event, nor vapor release rates characteristic of ORVR 

systems. 

Battelle's treatment of proximity to ignition sources assesses the 

likelihood of various ignition sources being close to leakage from 

evaporative and ORVR system components. Battelle discounted ignition 

sources outside the engine compartment. This was apparently done because 

Battelle believed that there is a low risk of ignition for leakage outside 

the engine compartment. However, ignition from the very hot surfaces 1n 

the exhaust system is clearly a possibility. Further, no ignition sources 

representing crash-induced sparks, maintenance-induced sparks, etc., were 

specifically considered. 

NHTSA believes the Battelle study arbitrarily assigns risk and hazard 

ratings. The analysis assumes that ORYR canisters will be located outside 

the engine compartment (determined by Battelle to be more dangerous), and 

that all existing evaporative system canisters are located in the engine 

compartment. There are, in fact, evaporative canisters located outside 

the engine compartment and nothing would preclude a manufacturer from 

locating an ORVR canister 1n the engine compartment. A fairer comparison 

would be to assess the hazards under similar circumstances. 

Several other aspects of the Battelle-methodology cause its results to be 

biased. First, Battelle rated all hazards according to the proximity of a 

fuel or vapor leak to a potential ignition source. The higher ranking was 

only assigned to hazards inside the engine compartment. Assigning a 

uniformly low ranking to potential fuel or vapor leakage outside the 

engine compartment unfairly biases the report. Second, 50 percent of the 

ORVR systems considered In the study had the canister mounted outside the 

engine compartment, while 100 percent of vehicles that did not have ORVR 

systems had front-mounted evaporative canisters. This assumption, 

combined with the decision to include antispitback valves only in ORVR 

systems, also unfairly biases this study. 

It is also important to note that in several cases in which an ORVR system 

is judged by Battelle to have a smaller risk than a current evaporative 

system, the rear-mounted canister is cited as a reason. Mounting the 

canister in the rear may reduce risks, but it does not remove them. The 

high exhaust system temperatures currently found in vehicles raise exhaust 

system component surface temperatures high enough to ignite fuel and 

vapors. The elevated temperatures also lead to much shorter exhaust 
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syst .i cc-rrponent life. Exhaust leaks occur and are dangerous ignition 

sources. 

Examples of such problems are very common in NHTSA investigations. The 

fires that led to Ford's 1987 recall of approximately 180,000 ambulances 

and Econoline vans were fires that started under the vehicles in areas 

near the fuel tanks and exhaust system. Ford has recently modified the 

1987 recall to install longer life stainless steel mufflers on ambulances, 

due to the numerous fires in which it was determined that the ignition 

sourco was most likely a blown muffler. 

As a.i example of how Incorrect the results of the Battelle study are, 

consider its primary conclusion that the major risk to motor vehicle 

safety due to fires occurs during refueling. This is factually 

incorrect. Based on data quoted by EPA, an annual .average of 1,655 

post-collision fire fatalities occurred during the 1980 to 1984 time 

period. EPA also cited statistics that estimate there are 20,000 

collision-related fires every year. Conversely, EPA estimates of 

refueling fires range from 60 to 148 annually. Thus, the post-collision 

fire occurrence is orders of magnitude greater than the occurrence of 

refueling fires. These real world data contradict Battelle's findings 

that the largest contribution to fire risk is during refueling. Such an 

erroneous conclusion casts doubt on the methodology and results of the 

entire Battelle study. 

NHTSA has consistently maintained the Battelle report does not adequately 

address the concerns which NHTSA believes pose the most serious safety 

questions regarding onboard vapor recovery svstems. NHTSA remains 

concerned that the vapors generated may,not be safely purged, particularly 

in situations of high ambient temperatures or heavy engine loadings. It 

is likely that motorists will experience a variety of problems, including 

stalling, excessive exhaust system and resultant underbody temperatures, 

fuel line and fuel line coupling failures, overheated fuel tanks and fuel, 

the potential for canister breakthrough, and poor driveability 

performance. The Battelle study did not address any of these potential 

problems. 

Finally, the Battelle study is a qualitative risk assessment. A 

fundamental concern with that study Is that it is dependent on numerous 

assumptions and biases. This 1s precisely why NHTSA concluded it was 

imperative to conduct scientific laboratory testing as part of its 

assessment of ORVR safety. These tests were definitive—under certain 

conditions representative of the motor vehicle crash and operating 

environment, ORVR canisters broken due to collision forces and exposed to 

ignition sources characteristic of the motor vehicle environment would 

ignite and result in self-sustaining fires. Based on these tests, ORVR 

systems would increase the risk of fire and hence result in an increased 

safety risk compared to current vehicles. Such a finding 1s much more 

compelling than a speculative assessment, such as the one performed by 

Battelle. 

Arthur D. Little (ADL) has critiqued the approach and findings of the 

Battelle report. API commented on ADL's critique and included a Battelle 

review of ADL's critique. The Battelle review does not address either ADL 
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or N;.,'5A's concerns regarding the original Battelle report. The Battelle 

review provides no substantive data to factually address any of the issues 

in the ADL critique. The Battelle review states that ADL found that all 

four ORVR configurations had antispitback valves, when only three did. 

This was not a misunderstanding on ADL's part. During a meeting between 

ADL and Battelle in April of 1989, this issue of four versus three 

antispitback valves was brought up and ADL explained that, as three had 

antispitback valves and the other had a seal in the filler pipe, which was 

treated by Battelle as an antispitback valye in Battelle's analysis, ADL 

grouped all four in their analysis. During the April meeting, Battelle 

stated that the ADL position was a correct grouping. 

ADL stated that vulnerability to tampering should have been addressed 

differently by Battelle. Battelle responded that they did address this in 

their report. ADL's critique was not that Battelle Ignored tampering, but 

that it treated tampering in a manner that eliminated it from any 

influence. For example, as indicated in the hazard probability scale on 

page 54 of Battelle's report, "tampering" in the charts 1n the appendix of 

the roport are classed as D, "Unlikely but possible to occur in the life 

of a vehicle", or £, "So unlikely, it can be assumed occurrence may not be 

experienced in the Hf e of a vehicle." These classifications are unduly 

low, in light of information published by EPA regarding surveys of 

evaporative systems "tampering", particularly if data on carbureted and 

higher mileage vehicles is Included. Since 10 years or 100,000 miles is 

considered by Battelle to be vehicle Hfe , based on EPA figures, £ "Likely 

to occur sometime in the life of a vehicle" would be a more appropriate 

risk rating. It 1s also Ukely that fuel tank fill and driveability 

problems will be greater with ORVR systems than in current vehicles. 

Thus, "tampering" will also likely increase, due to increased owner 

dissatisfaction. Suffice 1t to say, NHTSA does not believe the Battelle 

review submitted with API's comments in any way undermines ADL'S critique 

of the original Battelle report. As stated previously, NHTSA concludes 

that the original Battelle report does not adequately address the concerns 

NHTSA believes pose the most serious safety questions regarding ORVR 

systems. 

3. Vaoor Release During Refueling 

Some commentors suggested that safety concerns could be resolved by 

locating the ORVR canister in the rear of the vehicle or by manufacturing 

canisters, hoses, and connectors of materials and designs that will 

minimize potential problems. 

NHTSA safety concerns cannot be resolved by finding a "safe" canister 

location. Other ORVR components such as filler pipe valve units, liquid 

vapor separators, larger vapor hoses, and vapor vent valves will also 

increase the likelihood *** fuel and vapor release in the event of system 

failure or a collision. In addition, moving the-canister away from the 

engine is likely to require the use of longer hoses and more connections. 

Further, it should be recognized that potential ignition sources are not 

located only in the underhood area. Potential ignition sources, including 

hot surfaces, potential arcing wires caused by shorts and other electrical 

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by 

thi 

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cert; 

Others, any ORVR HI M uutsuviuiiai iy nurca^ e 

safe'.y, which is NHTSA's fundamental concern, 

There were comments concerning the laboratory tests conducted at the 

Vehicle Research and Test Center (VRTC), Included as Appendix III in the 

NHTSA report. (NHTSA's assessment of Battelle's critique of these tests 

will be addressed later in this document.) These tests were conducted to 

determine whether fires could occur in laboratory' tests designed to 

simulate charcoal canisters which lose their integrity and other types of 

ORVR system failures. Ignition sources represented such motor vehicle 

environments as hot exhaust surfaces, fires, electrical sparks, and 

collision-induced sparks. 

Appendix III documents the test procedures and test results used In the 

VRTC testing. The documentation includes information on all equipment 

used as well as the methods for all testing. The hot surface was 

represented by a hot plate and a heating coil, devices that exhibited 

surface temperatures well within the range of current exhaust system 

temperatures. Auto manufacturers reported that normal exhaust 

temperatures currently range from 1,100 to 1,500 degrees F. Thus, NHTSA 

believes that both the hot plate and heating coil model potential ignition 

sources likely during a crash or refueling event. While the frequency of 

such occurrences cannot be estimated, they will, in fact, occur. 

NHTSA testing demonstrates that evaporative canisters lose their integrity 

in certain laboratory crash tests. This provides the opportunity for fuel 

vapors to be exposed to potential ignition sources. The NHTSA laboratory 

testing with canisters was done to assess safety performance of such 

damaged canisters under specific and unique circumstances. These tests 

were a scientific approach to analyze whether an increase in the amount of 

flammable fuel vapors, a highly combustible material, would pose a safety 

risk. The conclusion was that increased vapors associated with ORVR 

systems would increase the risk of fire. While ORVR component location 

and construction materials are Important, all ORVR systems will result in 

increased safety risk and have a negative Impact on safety. 

EPA has requested an identification of the portion of the NHTSA report 

indicating that the hot plate successfully Ignited vapors from ruptured 

canisters. The discussion of testing and results of canister ignition 

using a hot plate is completely described in Appendix III of NHTSA's July 

1991 report. A typical setup for canister testing using the hot plate 1s 

shown in Figure 4. The hot plate is described In Appendix Table 1; it is 

a General Power Equipment Company Model HP-120, rated at 1100 watts at 12C 

volts. On page 4 of the report, the hot plate's surface temperature of 

approximately 1,000 degrees F is given. Table 2 indicates that test runs 

12, 21, 24, 11, 18, 15, and 27 were conducted using the hot plate; each 

test resulted in combustion (flame) of the gasoline vapors released by the 

charcoal canisters. These tests demonstrate that the 1,000 degree F hot 

plate ignited vapors from ruptured canisters. 
P.12 

Another question was raised as to why NHTSA referred to the 1,200 degree F 

surface used in tests involved in vapor flow from a 5/8 inch hose as a 

"modified" heating coll. A commercially available space heater was 

located and the Nlchrome heating wire was removed from the heater and 

connected to a rheostat to control the surface temperature of the Nichrome 

wire. The only modifications were the removal of the wire from the heater 

box and the connection of the rheostat. The purpose of this heating coll 

was to provide an additional hot surface with a temperature range within 

that of normal exhaust temperatures. Thus, both the hotplate and the 

heating coil provide an appropriate "model" of heat sources present during 

vehicle operation, even though it 1s not possible to accurately quantify 

failure rates.

 : 

4. Fire Risks Posed bv Existing Evaporative Svstems 

One of the areas in which comments were received concerning NHTSA's Report 

1s the safety performance of existing evaporative systems. The Center for 

Auto Safety (CAS) presented comments concerning NHTSA's consumer complaint 

file and claimed that this file demonstrates the satisfactory safety 

performance of evaporative vapor control systems. Additionally, comments 

were submitted regarding NHTSA's statistical analysis of real-world crash 

data to assess the relationship between fire occurrence and presence of 

evaporative systems. 

NHTSA has previously provided a detailed response to CAS's claims 1n its 

October 25, 1991, submission to this Docket. CAS uses NHTSA's complaint 

file (complaints received from the public) to allege existing evaporative 

systems do not pose significant in-use fire risks. However, based on the 

number of consumer complaints that CAS has received and forwarded to 

NHTSA, just the opposite is true. These complaints have involved fires, 

injuries, and deaths caused by problems that were directly related to 

evaporative systems and later corrected by defect recall actions that 

involved remedies to the evaporative systems. 

The most illustrative example relates to NHTSA's investigations of fires 

in Ford E-350 ambulances and vans. CAS forwarded over 100 complaints of 

fires in these vehicles to NHTSA. CAS 1s also aware that during the 

course of these investigations, NHTSA received 467 complaints of stalling, 

fuel expulsion and fires from owners of these vehicles. The fire problem 

with the Ford E-350 vehicles, which Ford recalled, were directly related 

to the evaporative system. In order to correct the problem, Ford (after 

approval of the EPA) installed by-pass valves that vent evaporative vapors 

to atmosphere, rather than to the charcoal canister. This was to preclude 

the purging and burning of these vapors in the exhaust system, which was 

largely responsible for the excessive underhood and underbody temperatures 

these vehicles were experiencing. 

The Office of Defects Investigation (ODI) consumer complaint file 

currently contains over 200,000 reports. It is impossible to precisely 

determine how many of these reports reflect complaints about problems with 

or due to evaporative systems. Most owners complain of symptoms and 

request that ODI, which possesses the technical and investigative 

expertise, investigate the problem and determine the cause. Owners often 

report that their vehicle stalls, spews fuel from the filler pipe, or 

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catches fire. In order to precisely determine how many vehicles had 

evaporative system problems, the agency would have to inspect each vehicle 

immediately after receipt of the letter. Any analysis of a summary of 

these letters,'in an attempt to ascertain how many owners were 

experiencing problems related to evaporative systems or the effects of 

evaporative systems on vehicle performance, would not produce accurate or 

meaningful results. Most owners do not know how an evaporative system 

works or even that their vehicle has an evaporative system, and it would 

be surprising if any owner complaints mentioned the evaporative system by 

name. 

Several commentors have repeated the assertion by CAS at7the September 26 

public meeting that the NHTSA consumer complaint file contains only 27 

complaints related to evaporative emission systems. As previously 

mentioned, CAS submitted over 100 of the 467 complaints of stalling, fuel 

expulsion and fires from owners of the Ford Econoline vehicles recalled 

(as previously explained) for problems caused by the presence of 

evaporative systems. Forty of these vehicles were destroyed by fire and 

there were 24 injuries reported. Yet, not a single letter from the entire 

467 received ever mentioned the evaporative system, which was determined 

to be the cause of their problems. 

A number of commentors criticized NHTSA's discussion of safety recall data 

in Appendix I of its report. These data represent the safety recalls 

conducted due to safety problems associated with evaporative vapor control 

systems. First, it is important to note that these recall data were not 

used by NHTSA as a basis for its principal findings and conclusions 

concerning ORVR safety. Thus, any concerns associated with the substance 

or characterization of these recall data are irrelevant to NHTSA's 

conclusions regarding ORVR safety. These recall data merely Indicate that 

there are safety problems with charcoal canister-based evaporative vapor 

control systems in today's vehicles. In that regard, they are Indicative 

of even greater safety concerns with canister-based ORVR systems. 

Some commentors noted that the descriptions of defects set forth In 

Appendix I to the NHTSA report are different from the summaries routinely 

made available to the public. The recall descriptions in Appendix I were 

derived from the data and analysis obtained in NHTSA's defect 

investigations. On the other hand, the summaries most often are limited 

to a description of the nature of the safety problem and the vehicle 

component that was defective. Further, the recall descriptions in 

Appendix I were written to explain the relationship between the defect and 

the evaporative emission systems. Official recall reports filed with the 

agency in accordance with NHTSA regulations, and the summary of those 

reports, are often not ^ry detailed or descriptive. Frequently, it is 

difficult to determine the actual vehicle components being remedied. 

Accordingly, NHTSA prepared the recall descriptions 1n Appendix I to 

clarify that the recalls in question did indeed relate to evaporative 

systems. For example, data in ODI files for some of the recalls described 

in Appendix I indicated that the recalls were related to high exhaust 

temperatures which were associated with evaporative vapor control 

systems. The official recall report and associated recall summaries did 

not mention this relationship. However, as mentioned above, this is not 

unusiil, since official recall reports generally do not contain detailed 

tech cal descriptions of the defect. 

11 
P.14 

! 

In noting that NHTSA's report Indicates that all of the Identified 

evaporative system defects "were remedied after the recall order," EPA 

appears to suggest that this minimizes or alleviates safety concerns. 

While it is true that NHTSA 1s not aware of any instance in which a safety 

problem with the evaporative system could not be remedied, this 1s not 

determinative. The average recall rate (the percent of recalled vehicles 

remeJied) for safety recalls is about 70 percent. Thus, some vehicles are 

not remedied and the safety risk will remain. Moreover, most recalls are 

not commenced until after incidents have already occurred. In general, 

only after fires have occurred will the manufacturer or NHTSA be aware 

that there 1s a defect that needs to be remedied. • 

EPA also asked whether NHTSA had Information regarding the number of 

casualties resulting from evaporative canister fires and questioned the 

significance of NHTSA laboratory testing included in tne report that 

indicated a likelihood of evaporative canister fires. Underbody and 

underhood fires in motor vehicles generally consume a large portion of the 

vehicle. In such events, there is virtually nothing left of vehicle 

contents made of plastic and rubber, such as charcoal canisters and rubber 

hoses. It is thus impossible to precisely determine how many of the 

approximately 1,300 fatalities and 12,000 injuries which occur annually in 

light vehicle crashes involving fire are related to evaporative canister 

fires. Nevertheless, the NHTSA report clearly demonstrates that current 

evaporative canisters can and do lose their Integrity in crashes and 

release the gasoline vapor contents. Further, the report demonstrates 

that when the canister contents are exposed to ignition sources 

characteristic of the motor vehicle environment, the contents will ignite 

into significant, self-sustaining fires. The significance of the NHTSA 

laboratory tests is they demonstrate that 1n events characteristic of the 

motor vehicle operating environment, charcoal canisters can result in 

significant and self-sustaining fires. This leads to the conclusion that 

fire risk will increase with ORVR systems, with a definitive, if 

unquantifiable, negative impact on safety. 

The NHTSA report also estimated the safety impact of evaporative systems 

on fire-related crashes, based on real-world crash data experience. The 

comments provided by API on the NHTSA analysis were submitted by 

Dr. C. James Sample and Mr. Ralph Mlttl. These comments were the only 

substantive ones provided on the statistical study, thus they will be 

addressed in detail. The conments can be classified into two general 

categories: (1) alleged incorrect vehicle model specification, and (2) 

lack of sufficient availability of statistical results. 

Comment: "In the [NHTSA] paper, Ms. Hertz (note - a NHTSA statistician) 

attempts to show that there is a statistical increase in the probability 

of a vehicle fire occurring when a vehicle is equipped with an onboard 

evaporative canister. It is the strong opinion of this writer that this 

is a wery different purpose than the stated objective to 'conduct an 

independent analysis of the subject of vehicle fires associated with the 

absence/presence of evaporative canisters [as stated in the NHTSA paper on 

page 1, third paragraph].'" 

12 
> I -tUwU U 

P.15 

Analysis: This assertion misrepresents the objective of the NHTSA 

analysis. As stated in NHTSA's summary report, "The purpose of the 

current Investigation was to conduct an independent analysis of the 

subject of vehicle fires associated with the absence/presence of 

evaporative canisters, using police-reported accident data contained 

state files available to NHTSA." 

in 

Comment: "... accident year is included to 'account for potential 

systematic increases in the reporting of fire over time.' Unless there is 

some basis for this assumption, and none is alleged, there 1s no reason to 

include the variable. It is well known that the total number of reports 

have increased over time, but to speculate that the number of accidents 

involving fire has Increased faster than accidents not Involving fire is 

not supported or even addressed." 

Analysis: The authors of the comments clearly do not recognize the 

situation disclosed by the statistical regression analysis. That 1s, the 

possibility that there could have been a systematic increase in the 

reporting of fire, due either to an increased emphasis by police agencies 

to identify vehicle fires, or a change in the method of coding vehicle 

fires on police accident report forms. The incorporation of a variable 

for accident year would account for a time trend in the occurrence or 

reporting of vehicle fires. Not accounting for this possible trend and 

finding an increase in vehicle fires before vs. after the introduction of 

evaporative emission canisters would leave the analysis open to the 

competing hypothesis that the observed increase in vehicle fires could be 

confounded with and attributable to changes in police reporting of fires 

ower time. 

Factors were included in the model that could lead to misleading estimates 

of the Emiss variable [absence/presence of evaporative canister] because 

they could not be presumed to be evenly distributed among model years. 

The inclusion of accident reporting year (which obviously 1s associated, 

but not highly collinear with model year, since vehicles of various model 

years are involved in crashes in the various accident years) does not make 

any assumption about reporting bias; on the contrary, that is exactly the 

way to ask the question without pre-judging the answer. 

Comment: "... vehicle age has to be correlated with the Emiss variable 

(since the Emiss variable 1s also a function of car age at the time the 

accident occurred). Entering this variable Introduces, or at a minimum 

increases the multicollinearity In the regression. This directly impacts 

on the ability to evaluate the significance of Cl [the coefficient of 

Emiss], which 1s what she [Dr. Hertz] is using to present her argument." 

Analysis: This comment demonstrates a misunderstanding of collinearity 

and its effect on regression results. When variables are highly 

collinear, the regression analysis cannot associate the "explained 

variation in the response variable" to either of .the collinear variables 

(i.e., both variables appear to explain the same changes in the response 

variable), resulting 1n a singularity 1n the design matrix, and an 

inability to provide estimated coefficients with well-behaved standard 

errors. This is not the case. The fact that these variables exhibit some 

degree of correlation (but not so great so as to result in computational 

13 
P.16 

difficulties) based on their definition 1s not a problem. It would be 

unusual in common regression applications for all regressors to be 

statistically independent. 

Comment: "In this analysis presented by Ms. Hertz, the primary objective 

of the analysis 1s to evaluate the Importance of'the beta coefficient on 

the Emiss variable (Cl). Given this objective, it is necessary for all 

beta coefficients (C0,...,C3) to be statistically significant. If this 

condition is not met, it is not possible to evaluate the contribution of 

any one beta coefficient to the overall findings of the regression." 

Analysis: The crux of the argument appears to be that a regression model 

is not valid unless all the predictors are found to be statistically 

significant. This is an assertion without basis in the statistical 

literature. One can combine estimates from various analytical sources. 

The key to this is to consistently "carry forward" the associated standard 

errors with their estimates to assure that no Information is lost. 

Comment: "As the three coefficients [I.e., three of the four state Emiss 

variable coefficients] are statistically insignificant, it is not possible 

to group them and use them for interpretation as is done the her 

[Dr. Hertz's] paper. As noted above, combining insignificant beta 

coefficients, regardless of the relative weighting technique, cannot be 

justified." 

Analysis: There is no such statistical principle as that alleged by the 

authors of the comments. 

Comment: "Finally, it is argued that only four states were found with 

sufficiently detailed and consistent data to be used. If this is so, 

there is no reasonable justification for not combining the data sets and 

fitting one regression through the combined data set. The alternative 

used, to determine four separate regressions and then to weight the 

coefficients by the relative variance is not justifiable." 

Analysis: The question about combining results across states is more 

subtle than the previous issues raised. The coefficients that are found 

to be significant are indeed important, but the converse is not true. 

That is, if a coefficient 1n a regression 1s not found to be significantly 

different from zero (as indicated by its p-value or its standard error in 

relation to its point estimate), one merely fails to reject the null 

hypothesis that the factor makes no difference. This distinction is a 

fundamental concept in statistics: if each of ten investigators tosses 

the same coin twice and gets two heads, none of them individually can 

reject the hypothesis that the coin 1s fair (i.e., a 50-50 proposition for 

heads vs. tails) at a significance level less than 0.25. 

So why not simply combine data from all the states and run a single 

regression? Because reporting criteria for accidents differ greatly 

between localities. Combining the data in this fashion would have been 

equivalent to the assumption that the overall probability of fire given 

that a police-reported accident occurred is the same from state to state. 

14 
i iLjV-i ("13. -

P.17, 

The NHTSA study "Motor Vehicle Fires in Traffic Crashes and the Effects of 

the Fuel System Integrity Standard0 (DOT-HS-807-675, November 1990) states 

on page 2-13 that: 

"Another observation frora Table 2=1 is that fins rates vary 

States, particularly between Michigan, Ohio and Maryland, which have 

consistently higher rates, .and Illinois and Indiana, whieh have 

similar rates, but considerable b^low thosg for the first three 

States. Reasons for these differences are not readily apparent, but 

the most likely candidate is beligviad to b% reporting differences 

among the States.0 

For example, Table 2-2 shows that for model y^ r 197S, the fire rate per 

1,000 passenger cars in accidents rangts from © low of 1.027 for Illinois 

to 5.024 for Ohio, a difference of almost five-fold. • 

On the other hand, combining this results across states from separate 

regressions rests on a much more plausible assumption. That is, that the 

change (if any) in the log odds of fire associated with the presence of 

evaporative canisters is the sam© from state to state. This resulted in 

four independent unbiased estimates of the Emiss coefficient, one for each 

state. These can then be combined most efficiently, in the sense of 

minimum variance, using coefficients that are inversely proportional to 

the variance (see Fleiss, "Statistical Methods for Ratios and 

Proportions", Chapter 10). 

The choice of states and data was bused on th@ requir&mnt that the stat®, 

first of all, supply NHTSA data. Second, it was necessary that the data 

include all occurrences of fire tnd that fire b@ defined at the vehicle 

level, i.e., the accident coding must indicate which vehicle the fire 

occurred in. Further, the earliest possible data was used. This is 

because the change took place in 1171 and regression models assume that 

the effect of age, or anything else, is linear. That assumption could 

become questionable beyond a reasonable rang® and could potentially 

invalidate the model. Those ar© the circumstances that imposed 

limitations on the quantity of available data. Of course, mor® data would 

always be welcome, but th® following point should be borne in mind: The 

available data were accurate, and a thorough analysis was conducted that 

included confidence limits as wtil as point estimates. 

Comment: "The standard statistical diagnostics are not provided in 

support of th© regression results accepted by the author [Dr. Hertz] and 

used in the analysis." 

"This is a paper in which a rather complex regression technique is used, 

insufficient information is provided for any reader to evaluate the 

statistical accuracy of the regression equations . . .." 

"Additionally, these problems are magnified by her failure to provide any 

statistical information on C2 or C3

 a 

O 0 0 0 

Analysis: The title of the NHTSA analytical section is "Summary of 

Evaporative Emission Control System Analysis". The operative word here is 

"summary". This is not a technical report documenting the entire 

15 

HHMUMUMMH^^^jjj^B—^^MB^^iMil i linn HMIliliillil i il lill 
JPJ8_ 

analytical effort. No such report was prepared on the effort due to time 

constraints. This was made perfectly clear in several telephone 

conversations with the authors of these comments, one of which was 

identified 1n footnote number 4 on.page 4. The authors appear to imply 

that the absence of complete documentation means that there 1s something 

to hide. This 1s simply untrue. Dr. Sample.contacted Mr. T. Klein (Ms. 

Hertz's supervisor) on two separate occasions, and a follow-up telephone 

conversation occurred between Mr. Klein and Mr. Mlttl. During all of 

these conversations, NHTSA offered complete documentation to Dr. Sample 

and Mr. Mlttl, Including a complete set of printouts of the modeling 

results and any other such information which would assist them In their 

review. This offer was refused by the API representatives, for unknown 

reasons. In addition, in one conversation Or. Sample clearly explained 

that his area of expertise was economics, and he would have to enlist the 

aid of a statistician from API 1n order for Mr. Klein to explain the 

statistical methodology employed in the NHTSA analysis. As a result of 

the conversation with Mr. Mlttl, Mr. Klein went so far as to xerox and 

telefax a section from the textbook "Statistical Methods for Rates and 

Proportions" (Fleiss) which explained the use of methods for combining log 

odds ratios from various statistical analyses. During each conversation, 

NHTSA staff volunteered to provide complete documentation of the analysis, 

references to textbooks that could provide detailed documentation of the 

statistical methodology, and time for further discussions related to areas 

of concern on the part of API representatives. 

The Center for Auto Safety commented that the above-referenced summary 

is in fact the entire analysis. The information in the NHTSA report 

concerning the analysis was meant to be a statement of the methodology and 

principal findings of the analyses. As discussed, NHTSA offered 

interested parties complete technical documentation of Its analysis. The 

Information was not, however, requested. 

Comment: "A much clearer picture of the trends in vehicle fires 

associated with crashes is seen by reviewing the actual data than 1s 

achieved by unnecessarily complicated and erroneous statistical analysis." 

Analysis: Table I from the API comments displays, for each of the four 

states, for a fixed time period for each state, the fire rate by model 

year. Predictably, the graphs generally slope downward because, for the 

same reporting years, the earlier model year cars are older. It could be 

remarked that the Michigan rate goes up Instead of down In model year 1971 

(Table I), but attaching any importance to the matter would be simply 

participating 1n the obscurantism. The question was "Does the presence of 

evaporative canisters have a statistically significant association with 

the occurrence of fire?" and simplistic pictures cannot provide definitive 

answers. 

It 1s interesting to note that after citing alleged statistical procedure 

problems with the NHTSA analysis, API resorts to what is in essence a 

verbal and nonstatistical description of data on the occurrence of vehicle 

16 
P.19 

fires, noting that there has been an overall downward trend. This is in 

spite of the fact that on page 9 of the API comments, the authors draw 

attention to the fact that the referenced NHTSA report concludes: 

"First, a Model Year, or age trend is noted In the fire rates - older 

vehicles tend to have higher rates than newer vehicles. This 

observation 1s generally consistent throughoqt the entire model year 

range of 22 years, and the trend 1s evident among all five State data 

bases." 

The authors propose that "This is the single conclusion of this study ... 

The newer the vehicle, the less likely is it to catch fife in a vehicle 

crash." In spite of this, the authors feel that the data provided in 

Table 1 and Figure 1, which are raw fire rates collapsed Into a single 

estimate for each model year representing accident years 1982 through 

1987, provide a "clearer picture." The authors apparently do not realize 

that vehicles of a specific model year vintage age over time, and that for 

a fixed reporting time period, the occurrence of a vehicle fire in an 

earlier model year vehicle would be more likely than 1n a later one. 

The nonstatistical and nonsubstantive explanation of fire risk provided by 

API cannot possibly account for the effects of vehicle age while at the 

same time contrasting vehicles with and without evaporative emission 

control equipment. 

EPA asked why four states were used 1n the accident data analysis 1n 

NHTSA's report, while the NHTSA study evaluating FMVSS No. 301 used six 

states. The analysis in the NHTSA report required specific data be 

included in the state accident files to be used for analysis. These 

requirements are more restrictive than used 1n the FMVSS No. 301 study. 

For example, information on vehicle model year and which vehicle 

experienced a fire were necessary 1n order to determine the relationship 

between fire occurrence and model year (necessary to determine the 

presence of an evaporative emission system). These requirements defined 

the state accident files that could be used in the analysis. 

5. NHTSA's Laboratory Testing at the Vehicle Research and Test Center 

API contracted with Battelle to critique the testing NHTSA conducted at 

the Vehicle Research and Test Center. These tests were conducted to 

assess the potential for fires in ORVR systems. The testing was directed 

at: 1) determining whether canisters which lose integrity due to a crash 

and are exposed to an ignition source can result 1n a fire, and 2) whether 

refueling vapor, which would enter the vehicle underhood and underbody due 

to broken or separated vapor hoses, would Ignite due to an ignition 

source. 

Battelle commented that the NHTSA tests were unrealistic since "no ORVR 

system would never [sic] be positioned 1n a motor vehicle where it would 

be openly and directly exposed to full impact." NHTSA believes that such 

a position 1s refuted by the data quoted in NHTSA's report in which 

evaporative canisters were found to lose their Integrity in 27 percent of 

17 
P.20 

t 

O u i lOX O 

full scale laboratory crash tests. In these tests, the internal contents 

of the canister were released or exposed. Further, in response to an 

information request from NHTSA, GM Indicated that 30-70 percent of 

evaporative canisters suffer loss of integrity in laboratory crash tests. 

These data indicate conclusively that canisters will, in fact, rupture 

when subjected to crash forces characteristic of the motor vehicle 

environment. Battelle's comment on the positioning of the ORVR system is 

irrelevant. Clearly, the system would not be purposely located in a 

position where it would be openly and directly exposed to impact. The 

issue is whether a canister, when subjected to the crushing forces 

associated with the range of real world crashes, would lose Its integrity 

and expose its contents to potential Ignition sources. Based on 

laboratory test data, the answer 1s yes. 

Battelle further states that the VRTC tests are bi'ased towards the 

creation of a laboratory environment In which ignition was probable and 

"not relatable to the more probable reality in which the absence of any 

one of the critical ignition criteria would greatly diminish the 

propensity for ignition; these fatal flaws 1n design would Invalidate the 

VRTC results and prohibit them from ever being used to estimate the fire 

risk posed by ORVR systems with any confidence." 

The logic of this statement is unclear. Laboratory tests, by their very 

nature, are used to assess the consequences of particular events 

characteristic of the real world. Battelle's argument that the absence of 

a flammable fuel vapor, oxygen or an ignition source would diminish the 

propensity for ignition is true but irrelevant. The issue is, can 1t 

occur. The VRTC tests documented that when conditions representative of 

the motor vehicle operating environment are encountered, a significant 

self-sustaining fire will often result. Battelle's position is that, 

since the probability of occurrence is small, the tests are flawed. This 

rationale would argue that all motor vehicle safety testing is fatally 

flawed, since all events resulting 1n a serious injury have a relative low 

probability of occurrence. NHTSA's mandate is to reduce highway safety 

risks. Thus, performing laboratory tests which address safety 

consequences of potential real world events is a prudent, rational and 

scientific approach to assessing safety risks. 

Battelle states that, in the NHTSA VRTC canister testing, some "23 percent 

of the gasoline containing canisters did not Ignite." Battelle indicates 

this "is compelling evidence that the confinement of gasoline vapor by the 

charcoal canister affords some degree of fire safety." Battelle seems to 

be arguing that, if 100 percent of the canisters Ignited, there would be 

no fire safety, but since 23 percent did not ignite, there is "some degree 

of fire safety." However, this is absurd, since 1t implies that Battelle 

believes that a fire occurrence in a majority of canisters is acceptable. 

Interestingly, Battelle agrees with a statement in the NHTSA Report, "it 

was recognized that these tests would represent specific and unique 

circumstances." Given that Battelle concurs with NHTSA'S characterization 

of the circumstances represented 1n the laboratory, it is unclear how it 

can assert that there is no evidence that these circumstances would ever 

18 
._. . P,2L 

NOU-27-193- id^J FROM US DOT/NHTSA ODI TO 83748368 P.21 

be representative of actual conditions. Battelle goes on to state that 

"real life conditions would be Tess conducive to ignition and more 

probable than those created in the VRTC tests." Further, Battelle states 

that "some of the fires constructed in th® VRTC study may be of 11ttl© 

consequence from a safety viewpoint.0 

These statements indicate that Battelle concludes that the likelihood gf 

fires such as those simulated in the VRTC tests hav® a low probability of 

occurrence and "may be of little consequence fro© a safety viewpoint," 

NHTSA recognizes that the probability of occurrence of such events is 

low. One only need recognize that there ar® soroe 166 million drivers in 

the United States and soma 27,000 are killed ©very yaar.' Thus, th© 

probability of a driver being killed is O0OOQI6 and thus the probability 

of not being killed is 0.99984. This low probability of death is not, 

however, a rational® for concluding that motor vehicle crashes do not 

constitute a serious public hsilth concern. Battelle's conclusion that 

because the probability of occurrence is low, hence, concern should be 

lew, is fundamentally flawed. NHTSA is concerned aboyt lou probability 

events since they are characteristic of the motor vehicle crash 

environment. 

Finally, Battelle's statement that the likelihood of fires such as those 

in the VRTC tests may be of little safety consequence indicates a 

substantial lack of recognition of the raissien of highway safety. NHTSA 

performed these tests to determine if events that create 11 serious risk to 

motor vehicle safety could be demonstrated in a laboratory envlpotifaent. 

The agency concluded that ORVR systems would indeed ereat© such a risk. 

Dismissing these test results hy stating they

 Dmay be of little 

consequence from a safety viewpoint0 is not compelling t© an agency 

charged with oversight of motor vehicle safety. Battelle's uncertainty, 

coupled with its recognition that the VRTC tests do hav© a probability of 

occurrence in the real world,, leads to a conclusion that the VRTC tests 

do, in fact, support a finding of increased safety risks associated with 

ORVR systems. 

A comment concerning NHTSA testing of canisters addressed the saturation 

level (the percent of the maxlmw fuel vapors a canister can store) of 

canisters. In NHTSA's testing, essentially all cases involving a canister 

fire occurred when the saturation level %%£®&4®4 SO percent. However, 

contrary to EPA's comment, there will be many instances in normal 

operation in which the saturation level is above 50 percent, as indicated 

by submittals to the docket and presentations at the public meeting. 

One coRSB$enter raised the issu© of the extent to which purging raises 

exhaust tesiper&tures. Evaporative control systems can affect exhayst 

system temperatures in a variety ef ways. One affect is purging, e.g., 

introduction of stored fuel vapors Into th© engine, coupled with increased 

oxygen to ensure more complete combustion. While MHTSA does not have data 

indicating the precise magnitude of exhaust temperature increase due to 

purging, the phenomenon is widely known and discussed extensively in motor 

vehicle emission technical documents. 

19 

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1

'

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P.22 

NOU-27-1991 16:21 FROM US DOT/NHTSA ODI TO 83748368 P.22 

6. Miscellaneous Comments on the NHTSA Report 

At the September 26-27, 1991, hearing, and in a subsequent written 

submission, the Petroleum Marketers Association of America (PMAA) claimed 

that, if NHTSA 1s concerned about complexity resulting 1n increased safety 

risks of ORVR systems, then PMAA would expect to see similar concerns by 

NHTSA regarding the enhanced evaporative system. Since NHTSA did not 

question the safety of enhanced evaporative systems, but did raise safety 

concerns regarding ORVR systems, PMAA states that "NHTSA's opposition to 

the onboard refueling system raises, we believe, serious questions about 

the credibility of Its report." The National Association of Convenience 

Stores and the Society of Independent Gasoline Marketers'of America made a 

similar argument. 

NHTSA did not address enhanced evaporative systems In Its report for two 

reasons. First, as noted 1n NHTSA's Report, a salient distinction between 

ORVR systems and evaporative systems concerns alternatives. Only one 

approach exists concerning evaporative emission control--onboard 

evaporative systems. The control of refueling vapor, however, has two 

alternatives--ORVR and control of refueling vapors at the fuel pump. From 

NHTSA's perspective, the fact that alternatives exist to capture refueling 

vapors, each with a different level of safety risk, is a legitimate 

consideration in ORVR safety assessment. Second—and perhaps most 

important--the Clean Air Act Amendments (CAAA) of 1990 require that EPA 

consult with DOT (NHTSA) conceming the safety of ORVR systems. The CAAA 

does not direct NHTSA to assess the safety of enhanced evaporative 

systems. Thus, consistent with statutory direction, NHTSA limited Its 

safety assessment to ORVR systems. If EPA requests our assessment of the 

safety risks associated with proposed evaporative systems, NHTSA will 

provide such an assessment. 

With respect to a comparison of the safety risk of ORVR systems and Stage 

II systems, one comment suggested that NHTSA had not considered the safety 

benefits associated with reduced fire risk at service stations, due to the 

ability of ORVR to capture refueling vapors. In its report and analysis, 

NHTSA concluded that since ORVR systems Increase motor vehicle safety 

risks and Stage II does not, It 1s reasonable for EPA to conclude that 

ORVR systems constitute an unreasonable safety risk. The NHTSA report did 

not ignore the safety benefits that ORVR would provide 1n terms of reduced 

fire risk at service stations. Since both ORVR and Stage II capture 

refueling vapors at service stations, both provide a safety benefit in 

that regard. NHTSA does not agree that ORVR benefits in this context 

would necessarily be greater than those associated with Stage II systems. 

Even aside from lead time and phase-in considerations, it will take many 

years before the entire fleet could be equipped with ORVR systems. On the 

other hand, Stage II controls could be implemented much more quickly. 

Moreover, NHTSA's primary focus was on the impact of ORVR systems on the 

safety of motor vehicle occupants. It 1s clear that ORVR would increase 

this safety risk,.while Stage II would not. 

The Center for Auto Safety presented comments at the September 26-27 

public hearing regarding NHTSA's report. NHTSA's response to the Center 

for Auto Safety's comments has been submitted to the rulemaking docket. 

20 
P.23 

I ^W ? 5 UNITED STATES ENTIRONMENTAL PROTECTION VGENCY ^- r , , 

\^rtw / WASHINGTON, H.C. 20160 7^ ' H~ 2-

/te*rf 

OFFICE OF 

AIR AND RADIATION 

MEMORANDUM 

SUBJECT: Refueling Emissions Regulations for 1990 and Later 

Model Year Gasoline-Fueled Light-Duty Vehicles, 

Light-Duty Trucks, and Heavy-Duty Vehicles -- ACTION 

MEMORANDUM 

FROM: J. Craig Potter (AR-443) 

Assistant Administrator for Air and Radiation 

TO: Lee M. Thomas (A-100) 

Administrator 

Introduction 

This Notice of Proposed Rulemaking (NPRM) announces the 

Agency's decision on the control of vehicle refueling 

emissions, proposing that a vehicle-based ("onboard") control 

system be required beginning in the 1990 model year.* An 

emission standard of 0.10 grams of HC emissions per gallon of 

dispensed fuel is proposed to apply to all gasoline-fueled 

vehicles. The proposed refueling emission test procedures are 

based on the current evaporative emission test procedures. 

The decision to control refueling emissions, and the 

choice of a vehicle-based program, form an integral part of the 

Agency's Post-1987 Ozone Strategy. As a nationwide program for 

reducing emissions of ozone precursors, onboard is part of the 

second phase of the four-part strategy announced in June. This 

action on refueling emissions is consistent with EPA's proposal 

to control the volatility of commercial fuel. Both proposals 

will be published simultaneously in the Federal Register. 

Leadtime constraints may ultimately necessitate an 

implementation date of 1991 in the Final Rule. 
P.24 

• 2 -

Background 

On the basis of the latest air quality monitoring data, 

EPA has estimated that 73 urban areas (61 non-California) 

currently exceed the National Ambient Air Quality Standard 

(NAAQS) for ozone. Approximately half the nation's population, 

over 100 million people, live in areas with ozone levels above 

the standard. In the absence of further controls on emissions 

of ozone precursors, air quality modeling indicates that 52 of 

the 61 non-California urban areas may fail to reach attainment 

by the December 31, 1987 statutory deadline. Additional 

modeling has shown that reductions of about 90 percent in the 

base-year emissions inventory would be required to completely 

eliminate the non-attainment problem. Refueling emissions are 

estimated to represent approximately two percent of the total 

emission inventory, making them a significant source of 

uncontrolled hydrocarbons. The control of vehicle refueling 

emissions alone will not be adequate to resolve the long-term 

ozone NAAQS non-attainment problem, but it is an important 

element in moving toward that goal. 

In addition to helping meet the need for controls on ozone 

precursor emissions in non-attainment areas, this proposal will 

lead to significant emission reductions in areas currently 

meeting the ozone NAAQS. These reductions are also very 

important, especially when it is recognized that many areas 

currently designated as attainment are only marginally meeting 

the standard. 

Beyond the need for improvements in ozone air quality, 

refueling emissions pose a potential health risk. One 

naturally . occurring component of gasoline (and thus of 

refueling emissions) is benzene, a listed hazardous air 

pollutant under Section 112 of the Act and a recognized human 

carcinogen. There is also evidence that gasoline vapors taken 

as a whole may be carcinogenic, although there is some 

uncertainty in this area. The results of our analyses show 

that the control of refueling emissions has the potential to 

avert up to 44 cancer incidences annually. 

Choice of Control Strategy 

There are two basic approaches to controlling vehicle 

refueling emissions, known as Stage II and onboard. Stage ll 

controls incorporate a vapor recovery mechanism as part of the 

service station fuel pump, and the recovered vapors are 

recirculated to the underground storage tank for collection and 

subsequent sale. Onboard systems capture the refueling vapors 

in a charcoal canister on the vehicle, where they are 

subsequently routed to the engine and burned. These systems 

are similar in concept and design to systems currently used to 

control evaporative emissions. 
P.25 

-3-

The rationale behind the choice of onboard controls is 

fully described in the attached preamble. This issue has been 

tne subject of several briefings and presentations in recent 

months and therefore will not be repeated here. In general, 

onboard provides greater long-term VOC emission reductions than 

Stage II for a similar or even better cost effectiveness, 

significantly reduces refueling related cancer incidences 

nationwide, and avoids many practical difficulties associated 

with implementing and maintaining a Stage II program. Stage II 

may be able to provide greater reductions than onboard during 

the initial few years of implementation, but even this 

advantage is uncertain. 

Economic Impact 

The purchase price of the average vehicle affected by this 

proposal is estimated to increase by about $19 (all costs are 

incremental to an assumed prior fix of current evaporative 

emission non-complaince problems), with an annualized total 

cost to the nation of about $200 million (spread across all new 

vehicle purchasers). When the fuel recovery credit is 

discounted to the year of vehicle purchase, it partially 

offsets the anticipated purchase price increase, leaving the 

average buyer with a net cost of about $14 per vehicle. 

The cost-effectiveness of onboard depends on precisely 

what benefits are counted and how they are valued. The 

estimated range of cost-effectiveness goes from negative (net 

benefit) when valuing non-attainment and attainment area VOC 

reductions plus benzene and gasoline vapor incidence 

reductions, to about $2200/Mg when valuing only VOC reductions 

in non-attainment areas. These values are well within the 

range of cost-effectiveness of ozone control strategies already 

implemented or under consideration. 

Expected Reactions 

As noted above, the issues of whether and how to control 

refueling emissions have already drawn considerable attention. 

Thus, EPA's announcement of this decision is expected to 

receive widespread coverage. 

The automotive industry remains opposed to onboard 

controls, and is likely to complain that EPA's analyses are 

unfairly skewed toward favoring onboard over Stage II. 

Manufacturers also will probably argue that this action must be 

coupled with controls on the volatility of commercial 

gasoline. Since we anticipate a simultaneous proposal of 

volatility controls, this may alleviate some of their concern. 

The petroleum industry, on the other hand, will likely support 

the decision to choose onboard over Stage II. 
-4-

P.26 

State and local air pollution control officials will 

likely join with environmental groups in welcoming the Agency's 

announcing a decision. They both may complain, however, about 

EPA'S delay in taking this action and the fact that it will not 

help in reaching the NAAQS by the statutory deadline. For this 

reason, it is possible that environmental groups, and some 

state and/or local officials, will press EPA to consider 

mandate Stage II controls in non-attainment areas in addition 

to onboard. 

Recommendation 

I recommend that you sign 

publication in the Federal Register. 

the attached NPRM for 

Attachments