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OAR Box 1830 

Prepped by Ollie Stewart 

Document Number: 

153) IV-C-120 

Docket Number: 

A-87-11 

Printed 11/13/2008 7:20:59 AM Sheet 153 of 232 
tr. Sarry Felrice 

Associate Administrator for Rulemaking (WR*-0l) 

national Highway Traffic Safety Administration 

400 Seventh Street, S.W. 

Washington, DC 20S90 

Dear tr. Felrice: 

*•* . 

Thank you for sending us a copy of the draft final report 

for the »WTS\ sponsored contract, "Study of Kotor - Vehicle 

fires" and providing ns an opportunity for review an4 comrneat. 

Tt is obvious fro-* the depth and scope of the analysts ,tbej a 

great deal of effort went into preparing this at 

finalised, this study will greatly enhance the * 

information available to the oubllc regarding »ot-. 

fires, We have •!ready oasse*4 along a few prellminar 

on t*»* reoort to *r, 7.7. Liu at our Karen It, 198t 

\i promised at that meeting this letter contains oor 

comments vhich *ave been organised intc tvo broad categories. 

""he first set of conurent S (Enclosure 1) ?eals mainly vith the 

test portion of the report in-* the concisions drawn from the 

-•at*. "he second set fSn-^osure 2) contains our more detailed 

comments on the text discussions and data tables. 

*•• hope these comments are helpful, *e understand vou 

Kave follow-on work nlanne*, so ve would appreciate the 

opportunity to review the reoort again once it M s been 

revised. Please cull me at ?TS ?"T4—Q409 if you have any 

questions regarding our comments.. 

Si nctr-r? v vouri, 

tr,"-

**\9n*\ \ "•.»*»j'*-i;-!f.( 15or

 n r o i e c t - 1 nage1 

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Enclosure 1 

EPA Comments on the Text Portion of the 

Draft Final Report, "Study of Motor Vehicle Fires" 

1. The report assumes its audience is very familiar with the 

NASS and FARS data bases and other NTHSA computer files. 

If this document is intended for public release, it would 

be helpful to provide information on these data bases 

including but not limited to: a brief discussion of the 

sample guality, changes that might have occurred to the 

data acquisition process over the years and their 

potential effects on observed data trends, national 

projection techniques from limited sampling, the basis and 

validity of redistributed unknowns, and the accuracy, 

completeness, and degree of coverage of the original 

police/fire reports. 

2. Page 4 contains some interesting statistics on the 

severity of motor vehicle fires (major vs. minor), and 

whether the fire was external or internal. Please discuss 

the relationship between major internal fires and the fuel 

system. Is the data specific enough to identify the point 

of impact or other similar information to allow an 

assessment of whether the fuel tank or fillneck was 

involved? 

3. A few clarifications need to be made regarding the role of 

fuel volatility in motor vehicle (MV) fires. First, it is 

important to understand the difference between a fuel's 

Reid Vapor Pressure (RVP) and its true vapor pressure. 

RVP (often used synonymously with volatility) is simply a 

measure of a fuel's evaporative characteristics at a 

single temperature condition (100°F). RVP can be used to 

distinguish the evaporative characteristics of two 

different fuels at the same temperature conditions. 

However, it is not possible to evaluate the role of RVP 

when fuels of varying volatility are compared at different 

temperatures. The true vapor pressure of a fuel depends 

not only on the characteristics of the fuel but on 

temperature conditions and other factors. It is the true 

vapor pressure that corresponds to the actual level of 

evaporation experienced by the fuel. 

Consequently, the discussion on page 7 of the report which 

refers to Tables 13 and 14 (the tables that resolve fire 

rates by month and state) requires modification. These 

two tables do not show the effect of fuel volatility, but 

may (if combined with the appropriate volatility and 

temperature data) reveal something about the role of true 

vapor pressure. This distinction is subtle but not 

insignificant. Further, since fuel volatility has 

steadily increased during the past 10 years, it may be 
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possible to evaluate the role of volatility in MV fires if 

the data in Table 13 were further resolved according to 

calendar year. Thus, it might be possible to identify for 

each month whether the use of higher volatility fuels in 

recent years correlates with more fires. A similar 

analysis could be performed with the data in Tables 33 and 

34. However, the contribution of other changes would have 

to also be evaluated and factored in before any clear 

findings can be made. 

In addition, on page 13, it should be made clear that EPA 

has not yet mandated fuel volatility changes. Therefore, 

any changes in fire rates linked to in-use volatility have 

not been related to EPA actions. Volatility changes that 

have occurred in the past were driven by market forces. 

Finally, the thesis discussed on the top of page 14 may 

or may not be valid. A more detailed analysis (such as 

the one just described) is required before such a thesis 

can be supported. 

MV component failures are discussed on page 8, however it 

is not clear what constitutes a failure. The discussion 

needs to clarify whether a failure is an owner complaint, 

a service bulletin, a recall, a combination of the three, 

or some other factor. It is also important to provide 

definitions for all key system categories such as fuel 

emission control systems. Finally, please explain what 

basis is used to determine where (which category) a 

failure gets filed. 

Page 9 of the report compares the rate of fire occurrence 

in accident involved vehicles with the rate of fire 

occurrence in motor vehicle component failures. When 

compared on this basis, component failure fires appear to 

occur about 10 times more frequently than accident fires. 

However, this comparison is deceptive at best, because the 

denominators of the two rates are not comparable. For 

example, just as it is not valid to compare rainfall rates 

of the entire United States with a single typically rainy 

city in Canada to determine which country receives more 

rainfall, it is not possible to draw any conclusions from 

a comparison of accident fire rates to component failure 

fire rates. A much better comparison would be between 

total counts of annual accident fires and annual component 

failures with fire, or with each expressed as a rate using 

a common denominator (e.g. registered vehicles) 

Page 10 mentions fire occurrences that are not reported in 

police accident records such as car fires in service 

stations or private roadways. We suggest that the 

National Fire Incident Reporting System (NFIRS) be 

examined to better characterize the extent of these types 

of fires. This data base contains a great deal of useful 
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information, and we believe you should consider 

investigating it. 

Also, on Page 10, the fire rate for reported accidents is 

used in conjunction with an annual estimate of all 

accident involved vehicles to establish an "upper bound" 

of annual car fires. This upper bound is unrealistically 

high because non-reported accidents are likely to be much 

lower in severity as compared to police reported 

accidents, and lower severity accidents are likely to have 

lower fire rates (Table 24). Therefore, the estimated 

105,000 car fires is not reasonable, even as an upper 

bound. 

We have a few comments regarding your statements 

concerning evaporative emission control systems on pages 

15-16. To begin with, it should be clarified that EPA 

evaporative requirements took effect beginning with model 

year 1971. Second, and most important, your casual 

connection between evaporative controls and the rise in 

fire rates between MY 66 and 75 is essentially 

unsubstantiated and is somewhat contrary to actual trends 

in the data. For example, when the standard errors are 

factored into the fire rates in Table 16, there is no real 

statistical difference between MY 67-70 (pre-evap) and 

MY's 71-74. In addition, Tables 27 and 35 show no 

difference between fire rates for MY's 70 and 71. As a 

matter of fact, Table 27 and 35 show that post-evap fire 

rates (MY's 71-74) were lower than pre-evap model years of 

68 and 69. 

When comparing fire rates of different model year 

vehicles, it is important to keep mind that a variety of 

factors can be responsible for differences found in the 

data. It is not a simple exercise to single out the 

effects of a lone factor such as evaporative control 

systems when other significant changes can occur 

simultaneously such as aging, driving pattern changes 

(e.g. as a result of fuel shortages), weather, speed limit 

changes, etc. Taking all this into account, it is our 

view that the data in the report do not support (even 

weakly) a suggestion that evaporative systems led to 

increased fires. Finally, if you are going to try to 

identify trends that might be associated with significant 

fuel system design changes, you may want to consider 

examining fuel injection in addition to evaporative 

controls and FMVSS 301. 
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9. On page 17, the report draws the conclusion that car age 

has a very strong influence on fire rates. However, this 

conclusion is not supported by all of the data and 

requires further analysis. For example, while it is true 

that the summary figures at the bottom of Tables 28b, 36, 

and 40 show a general increase in fire rates as the 

vehicles age, it is not valid to use these figures for 

comparison since all of the data for MY 66-72 vehicles 

were obtained when these vehicles were more than six years 

old. Thus, we have no way of knowing whether the high 

fire rates associated with MY 66-72 vehicles is a result 

of age or merely characteristic of those vehicles at any 

age. The relationship between car age and vehicle fires 

should be examined on a model year by model year basis, 

and only for those model years where data is available for 

all three age classes (<4 years, <6 years, and all 

vehicles.) At the present time, this data only available 

for a few select model years (75-78). When the data for 

these model years are examined, Tables 28b and 40 show 

virtually no relationship between vehicle age and fire 

rates, while Table 36 does show a fairly strong 

relationship. More definitive information and further 

analysis needs to be conducted' before any valid 

conclusions can be made. 

10. At the bottom of page 18, the report states that the fuel 

system is one of most frequently associated with defects 

or failure. We think this should be modified to state 

that the fuel system is one of the most frequently 

associated with reports of defects or failures. Just as 

failures associated with fire are likely to be over 

reported relative to other failures, we think fuel system 

failures are more likely to be reported relative to other 

types of failures since the fuel system directly affects 

vehicle operation. Also, fuel systems, unlike many 

vehicle components, are more likely to generate owner 

complaints in the event of a failure because these systems 

are expected to last for the useful life of the vehicle 

without need of maintenance or repair. 

11. Your conclusion on page 20 regarding the limited 

feasibility of an in-depth failure modes analysis of fuel 

emission control components due to sample size limitations 

is not supported. Based on limited reports of evaporative 

system components, you have drawn the conclusion that not 

enough data exists to characterize the failure rates of 

these components. Based on this information, it also 

seems valid to conclude that evaporative components have 

been very reliable, and that is why the sample size is so 

limited. 
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12. Finally, we have a few comments concerning the 

compatibility of your study with our "Analysis of Motor 

Vehicle Fuel Tank-Related Fires." First, we believe the 

raw data in our analysis is consistent with that contained 

in your report, and that where the analyses do overlap, 

the findings in the two reports are generally consistent. 

Do you agree with our assessment? Second, our analysis 

made no adjustments to account for non-reported fires. 

However, as already discussed, your study did make an 

attempt to scale up the reported data to account for 

non-reported fires. While we believe the scaling was 

unrealistically high, we would like to know whether you 

think our analysis underestimates the fire rate since it 

uses no scaling factor. If so, how would you suggest that 

the number of such fires be estimated? Last of all, our 

analysis assumed no relationship between post crash 

vehicle fires and age. This led us to the conclusion that 

pre-FMVSS 301 vehicle fire rates were higher than 

post-standard rates, and future fire rates would 

consequently be lower as pre-standard vehicles leave the 

fleet. Your report concluded a strong relationship exists 

between vehicle fires and age. Does this imply that you 

believe the projected fire rates in our analysis are too 

low? 
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Enclosure 2 

EPA's Detailed Comments on the 

Draft Final Report, "Study of Motor Vehicle Fires" 

1. Pages 1 and 2 of the report mention that data were 

examined from eight selected states in addition to NASS 

and FARS. However, the report only contains data from 

Michigan, Maryland, Ohio, and Pennsylvania with a brief 

mention of Washington. Where is the data from the other 

three states? Also, why were these states selected? 

2. On page 2, the report states that the NASS records in the 

years 1979-1985 were addressed. However, this is 

inconsistent with other places in the report which only 

consider NASS records from 1981-1985. 

3. On page 4, GAD and TAD should be clearly defined. 

4. If possible, it would be helpful if Tables 5-8 were 

further broken down according to fire location (interior 

vs. exterior) and accident impact site. 

5. NASS takes into account varying accident, fire, and injury 

severities. Who decides these severity levels, and is 

there a formal set of definitions to distinguish between 

levels? 

6. In the second paragraph of page 5, it would be helpful if 

you were to include the average number of annual 

observations of both Fire and No Fire cases. 

7. The discussion on page 5 regarding Table 9 is not clear. 

The counterintuitive result that is discussed concerning 

burns with no car fires is not at all obvious. An example 

which draws actual numbers from Table 9 might help to 

clarify this point. In addition, Table 9 is very 

confusing and could use some restructuring. More 

discussion of this table would be beneficial especially 

with respect to burns as a percent of all lesions. 

8. Page 6 of the report should state that FARS covers fatal 

accidents involving vehicles of all fuel types. 

9. Why does Table 15 only include FARS data from 1978 to 

1986? All other FARS data tables span from 1975 to 1986. 

10. On page 7, you should explain that "non-crash" includes 

non-collision and parked vehicles. 
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11. For Tables 16-19, you should include a brief explanation 

of how the standard error was determined and what 

significance it has. 

12. Why don't Tables 14 and 16-19 contain a separate column 

for non-crash fatal accident fires? 

13. Table 21 should include an explanation of what is meant by 

Body Types 3,4,5, and 6. 

14. Table 25 should define what is meant by K, A, and B injury 

severities. 

15. Please explain the significance of (5) = (2) + (3)+(4) in 

Table 32. 

16. Why do Tables 42 and 42a only cover 1984 when Tables 42b 

and 42c cover 1978-1984 and 1979-1984, respectively? 

Also, Tables 42 and 42a are very confusing. Please 

provide a more detailed explanation of these tables. 

17. Tables 51 and 52 require a footnote explaining what is 

meant by the "%" column. 

18. Tables 56 and 61 show data for MY 60. Is this a mistake? 

19. Why are there such a large number of unknowns in Table 66 

and 68? 

20. Why is Chrysler listed twice on Table 69? 

21. Tables 70-75 should indicate the calendar years and model 

years that correspond to the data entered in these tables. 

22. Table 43 shows a range of 16,000 to 28,000 annual 

incidence of car fires in police reported accidents 

nationwide, not 16,000 to 26,000 as stated on page 10. 

23. What is the source of the NASS national estimate of 

12,000,000 accident involved car occupants (page 11). 

Also, is it appropriate to use Pennsylvania data for 

national projections? Is Pennsylvania representative? 

Further, which data table provided you with the 

information needed to determine that 0.085% sustained 

burns as their most severe injury? Please show how this 

was calculated or pulled from the available data. 

24. Explain your suspicion on page 13 that the trend observed 

in the Pennsylvania data is due to changes in fire 

reporting protocols. Do you know for certain that changes 

occurred? If so, please explain what these changes were 

and why they affected the data as they did. 
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J,' 

25. On page 17, the report states that neither FARS nor NASS 

records distinguish between post-crash, pre-crash, and 

non-crash fires. However, Table 15 shows FARS data 

separated according to crash and non-crash events. Please 

explain. 

26. Shouldn't paragraph 3 of page 20 reference entries 16-19 

of Table 75 rather than entries 25-29? 

27. Finally, page 15 discusses the fact that overall counts of 

severe car crash fires are not as frequent as overall 

counts of lower severity car crash fires since severe car 

crashes are more infrequent than lower severity car 

crashes. However, this should not diminish the fact that 

severe car crashes have a higher rate of fire occurrence 

than lower severity car crashes. This is shown in Table 

24. Table 24 also shows a step increase in column (5) 

fire rates as crash severity increases from a TAD 4 to a 

TAD 5. Can TAD levels be cross-referenced to impact 

speeds? what does this indicate about the limits of FMVSS 

301? If higher speeds were required in FMVSS 301, would 

this be likely to force the step increase to show up 

between higher TAD levels instead of TAD 4 and TAD 5?