The Truth About Arson

by John R. Hall, Jr.

[--interFIRE VR Note: Tables and figures are not included in this electronic version. Please contact the NFPA Library (617) 984-7445 or e-mail library@nfpa.org for more information]

Of all the causes of fire, none receives as much attention as arson. Many groups are vocal on the subject, and arson figures prominently in popular fiction. One unfortunate result of all this attention has been the persistence of several myths about arson-myths that distract us from the real patterns and trends in arson and so may interfere with an effective attack on the problem.

Perhaps the most persistent myth about arson is that it's the fastest-growing crime in the United States. In fact, arson isn't growing at all, at least in terms of long-term trends. The downward trend may be seen in all the nationally representative estimates, including NFPA's survey, the national-estimates methods based on the U.S. Fire Administration's (USFA's) National Fire Incident Reporting System (NFIRS) and the NFPA survey, the FBI's Uniform Crime Reports estimates, and the U.S. Forest Service (USFS) reports on arson forest fires.

The perception that arson is increasing has been put forward by several sources. Among these are insurance-industry spokespersons, who base their conclusions, in part, on insurance industry estimates of the size of the arson problem. However, insurance databases aren't as representative as those cited above, and the methods used to make the estimates aren't as openly documented.

Others base their assertions that arson is rising on their familiarity with local trends. Arson may well be increasing in some communities, but the figures available show that the long-term trend is down, not only overall but also in all regions and in communities of all sizes.

A second persistent myth about arson is that it's hard to solve because it destroys all the evidence. Arson is hard to solve. Indeed, the fraction of all arsons solved by arrest ranges from 15 to 20 percent. But this same solution rate applies to all major property crimes, which tend to go unwitnessed.

Furthermore, incendiary and suspicious fires don't typically destroy all the evidence. In more than half of all the incendiary and suspicious structure fires that occurred between 1991 and 1995, there was no flame damage outside the room of origin. Incendiary and suspicious fires are more likely than most other fires to spread beyond the room of origin, but the differences in likelihood are small. In 40 percent of incendiary and suspicious structure fires, in fact, there's no flame damage beyond the immediate area of origin. If useful evidence were available, the fires would probably leave some of it untouched.

The real problem is that identifiable evidence is rare in any unwitnessed property crime. But methods that work to increase the solution rates for crimes such as burglary and motor vehicle theft may be effective with arson, as well.

The third most common myth about arson is that it rises during bad economic times, particularly recessions. In hard times, it's not unusual for local fire officials and insurance adjusters in some communities to report apparent jumps in some types of arson. However, the national statistics don't show evidence of a significant link.

During the 20 years covered by available statistics, there have been two recessions, one in 1982 and one in 1991 and 1992. In 1982, arson actually fell dramatically in most categories and by most measures, despite the recession. And during the more recent recession, arson leveled off. Though this leveling off is a less-favorable trend than the steady decline that occurred before 1989, it's continued well past the end of the recession.

From our statistical studies, we know that fires and fire death rates tend to correlate with poverty, but that needn't mean that fire experience risk responds rapidly or dramatically to year-to-year shifts in the economy. The relationship appears to be more complex than that. For arson in particular, most studies show, or at least suggest, that arson for profit is a relatively small share of the arson problem. And even if there were a statistically significant jump in arson for profit, the overall arson figure might not show a measureable jump and might even decline under the influence of factors affecting other, larger parts of the arson problem, such as juvenile firesetting.

Another variation of this myth is that businesses tend to commit arson at the end of the month to fix their otherwise dismal balance sheets. To see whether stores and offices had more incendiary and suspicious fires in the last three days of the month than at other times, an analysis was done using data from 1988 through 1992. At first, the answer seemed affirmative: Those days accounted for 10 percent of the days and 15 percent of the incendiary fires. On closer examination, however, this proved to be entirely an artifact of the Los Angeles riots of 1991, which went into the records as nearly 2,000 separate incidents. If those days are removed, the other days account for 10 percent of the days and the fires, showing no distinctive pattern.

The truth about arson

So what's the real story about arson?

Arson and suspected arson constitute the largest single cause of property damage due to fire in the United States. In 1996, the last year for which any national statistics are available, known incendiary and suspicious structure fires resulted in an estimated $1.405 billion in damage, or more than one of every six dollars lost to fire in structures. If the numbers are adjusted for fires of unknown cause and a proportional share is allocated to incendiary and suspicious causes, incendiary and suspicious fires of all types, not just in structures, normally account for roughly one of every four dollars lost to fire.

Incendiary and suspicious fires also accounted for 520 civilian deaths in structure fires with known causes in 1996, killing roughly one of every eight people who died in a structure fire that year. Approximately one of every seven structure fires with a known cause that occurred in 1996 was also listed as incendiary or suspicious, for a total of 85,500 structure fires.

Incendiary and suspicious vehicle fires added another $202 million to the damage toll in 1996, accounting for more than one-seventh of all the property damage due to vehicle fires for the year. Fortunately, though arson fires outdoors and in other areas add considerably to the total number of incidents, they don't add much to the total loss of lives or property.

All in all, NFPA statistics show a decrease in the number of incendiary or suspicious structure fires from 1995 to 1996 and no change for incendiary fires in vehicles. The FBI's statistics on the rate of arson offenses per 100,000 population also showed a decrease for structure fires, although the number of incendiary vehicle fires increased.

Structure fires

As Table 1 shows, the incendiary and suspicious fire problem in structures, which is by far the largest component of property damage, decreased in 1996. In fact, the 1996 total was the second lowest since NFPA first applied its current statistical methodology in 1977, exceeding only the 1993 total.

Direct property damage due to incendiary and suspicious fires also declined in 1996, as there was no major large-loss incident such as the World Trade Center bombing in 1993 or the Oklahoma City bombing in 1995. If we take inflation into account, the 1996 total was actually the lowest since 1977, when NFPA's statistics began.

From 1977 to 1978, the average loss per incendiary or suspicious structure fire, after adjustment to 1977 dollars, was just over $6,000. From 1979 to 1984, it fluctuated between $7,000 and $8,000 per fire, except for 1980, when it rose to nearly $8,900. From 1985 to 1988, it was just over $8,000, peaking at $8,300 in 1986. It fell below $8,000 in 1989 and below $7,000 in 1990, where it stayed in 1991. In 1992, it rose again to more than $9,000, and in 1993 it jumped to nearly $12,000. The next year, it fell back to just under $7,000, while in 1995, it rose to just over $7,000. In 1996, the ratio fell to just over $6,000, the lowest it's been since 1977.

If only incendiary fires are counted, the average loss per structure fire in 1996 was $17,100, slightly less than the FBI average of $17,900 per arson fire in a structure.

The total number of incendiary and suspicious structure fires was down 49 percent from its peak in 1977, while the number of civilian deaths in incendiary and suspicious structure fires was down 18 percent. The trend in civilian deaths in incendiary and suspicious structure fires has been erratic and hasn't followed the trends in fires and losses (see Figure 1). The 1978 figure of 930 deaths, which was nearly 50 percent higher than the figures for the years around it, was probably the result of an unusual sample. If this anomaly is ignored, deaths peaked in 1983, fell sharply in 1984, then rose each year until 1988, before falling again in 1989, rising in 1990, falling in 1991, rising in 1992, falling again in 1993 and 1994, rising sharply in 1995, and falling sharply in 1996 to the second lowest total recorded.

Figure 2 shows three sets of statistics on the size of the arson structure fire problem, the lowest of which comes from the FBI, which counts only arson offenses. The middle rates come from the NFPA survey, which counts incendiary and suspicious fires. Total FBI arson offenses track closely with NFPA figures on incendiary fires alone. For the period between 1982 and 1985, for example, the two average rates were within 0.2 percent of each other and never differed by more than 9 percent in any year. The highest rates shown in Figure 2 are from a national-estimates procedure developed by analysts at NFPA, the USFA, and the U.S. Consumer Product Safety Commission, which combines data from the NFPA survey and NFIRS. National estimates count incendiary fires, suspicious fires, and a proportional share of fires whose exact causes, whether unintentional incendiary, or suspicious, are unknown.

Vehicle fires

The number of incendiary and suspicious vehicle fires has fluctuated in recent years (see Figure 3). Though the 1996 total tied the 1995 total as the highest since 1991, it was actually below the average for the period between 1978 and 1996. After they were adjusted for inflation, the losses associated with incendiary and suspicious vehicle fires increased in 1996 for the third consecutive year (see Figure 4). In 10 of the last 15 years, the adjusted dollar loss has fallen in the range of $60 million to $80 million, and the 1996 figure was near the top of that range. The average loss per incendiary or suspicious vehicle fire was $4,300 in 1996, compared to the FBI's vehicle arson figure of $5,000. Both ratios vary substantially from year to year.

There's been no steady, sustained trend in the rate of incendiary vehicle fires. The national estimates, shown in Figure 5, show a drop from 1981 to 1982, but they also show sizeable increases from 1983 to 1986, which were almost fully reversed as of 1995. NFPA and FBI rates decreased and increased, respectively, in 1996, each to their fourth lowest levels in the years shown.

In any event, arson and suspected arson don't have the same lead role in property loss in vehicle fires that they have in structure fires. Just over one-seventh of vehicle property losses in 1996 were attributed to incendiary and suspicious fires; the share for structure fires was closer to one-fifth. Because a leading reported cause of vehicle fire property damage is collision, there's more uncertainty in cause profiles of vehicle fires. Collisions cause property damage directly, before fire begins, and it's difficult to separate damage due to collision from damage due to an ensuing fire.

Outdoor fires

Brush fires, grass fires, forest fires, trash and rubbish fires, and other incendiary or suspicious fires that occur outdoors constitute the majority of incendiary and suspicious fires. According to FBI statistics, they also constitute the smallest share of arson offenses (see Figure 6). However, USFS statistics for arson in protected forests far exceed FBI statistics. It may be that forest and wildland fires typically involve only plant life that's not part of any commercial activity. For reporting purposes, this would mean that they'd involve little or no monetary damage and might not qualify as arson or at least be less likely to be reported to law enforcement agencies. It may also be that the FBI Uniform Crime Reports system is under-represented among law enforcement agencies covering protected forest areas.

On the other hand, the databases reflected in the national estimates may have been somewhat unsettled with respect to outdoor fires before 1983. There's much more statistical uncertainty attached to national estimates of outdoor fires than to national estimates of structure or vehicle fires. The USFS figures also fluctuate far more from year to year, probably because ignitions of plant life are sensitive to annual variations in climate. Since the FBI figures and national estimates include outdoor trash fires, they're less sensitive to such climatic variations.

According to the USFS, incendiary fires typically constitute one-fourth to one-third of all fires on protected federal, state, and private lands. The incendiary percentage rose from 29 percent in 1980 to 31 percent in 1981 and 1982, then fell to 27 percent in 1983. It rose again in 1984 to 29 percent, then to 31 percent in 1985 and to 34 percent in 1986. In 1987, it fell to 32 percent, then dropped again in 1988 to 28 percent and to 26 percent in 1989 and 1990.

A one-time NFPA analysis done in 1986 may indicate the full size of the arson wildfire problem. This study, which included any outdoor wildland area but excluded fires involving direct dollar loss, showed 115,000 incendiary or suspicious fires in grass, brush, and wildlands, representing 23 percent of all fires in those properties.

In terms of monetary damage, both FBI statistics and national estimates show that losses in outdoor incendiary, suspicious, and arson fires add 1 to 2 percent, at most, to the reported damages in the corresponding structure and vehicle fires. Because it's difficult to assign dollar figures to lost wildland vegetation, this probably understates the size of the loss. Even allowing for that, however, losses in structures clearly dominate.

Arson by property type and area of origin

The largest share of incendiary and suspicious structure fires and losses in the United States occurs in residential properties, reflecting the large number of such properties in this country (see Table 2). In fact, nearly two-fifths of all incendiary and suspicious structure fires are dwelling fires, and more than 90 percent of the civilian deaths that occur each year in incendiary and suspicious structure fires occur in residential properties. In storage properties, half the incendiary and suspicious fires occur in dwelling garages, although most of the damage occurs in other, presumably commercial, storage properties. In some occupancies, such as educational properties, prisons and jails, vacant buildings, and buildings under construction, demolition, or renovation, roughly three- to four-fifths of all fire loss is incendiary or suspicious (see Table 3).

The average loss per incendiary fire is lowest, at $6,200 per fire, in health care and correctional institutions, which are closely monitored; in dwelling garages, at $6,300 per fire; and, at $3,800 per fire, in special structures other than buildings that are vacant or under construction, demolition, or renovation. Losses per fire are much higher-on the order of $30,000 and higher-in most nonresidential structures, specifically in public assembly properties and in stores and offices. Losses per incendiary and suspicious fire are particularly high in manufacturing properties.

Arson and suspected arson structure fires by community size

From 1992 to 1996, the rate of incendiary and suspicious structure fires per 100,000 population in cities with populations of 250,000 or more was roughly twice the rate for communities that have populations of 10,000 to 25,000. However, there's a significant incendiary and suspicious fire problem in rural communities, where the rate's only three-fourths that of the largest cities but more than 50 percent higher than that of communities with populations of 10,000 to 25,000.

There's a more pronounced pattern in the percentage of incendiary and suspicious structure fires between 1992 and 1996. In cities with populations of at least 250,000, the percentage of such fires was twice as high as it was in communities with populations of 25,000 (see Table 4). The FBI figures on arson rates in all properties, not just structures, show that large cities have an average rate two to four times that of smaller communities, depending on the year.

Interestingly, NFPA figures show that the different-sized communities have become more alike in all recent years but 1990. In 1981, the largest cities had an incendiary and suspicious structure fire rate three-and-a-half times those of towns with populations of 10,000 to 25,000. In the period between 1990 and 1993, the big-city rates were only two to two-and-a-half times the small-town rates, and in the period between 1994 and 1996, they were barely twice the small-town rates.

NFPA figures for most years show declining rates in communities of all sizes, with the rates of larger communities declining more rapidly than those of smaller communities. By contrast, the FBI figures show that rates for the largest and smallest communities aren't dropping as quickly as those of other communities. These two trends combined suggest that the rate of suspicious fires in larger cities is declining, possibly as a result of better investigation, but that the rates of incendiary fires and arson aren't, possibly because success in reducing confirmed arson offenses is being offset statistically by success in confirming suspicious fires as arson cases. The trends suggest the reverse in smaller communities-a decline in arson fires but not in suspicious fires, possibly indicating less success in confirming arson.

A special study of 12 states done by the National Institute of Standards and Technology in 1982 found the rate of civilian deaths in incendiary or suspicious home fires per 100,000 population to be about four times as high in cities with populations over 250,000 as the rate in communities with populations under 25,000.(1) The study also showed that deaths due to incendiary and suspicious fires were the only major category of home fire deaths for which the death rate in rural communities with populations under 2,500 was lower than the death rate in nonrural communites.

Arson and the criminal justice system

Although there was a net increase in arson arrests of 5 percent from 1987 to 1996, arson actually accounts for a very small and declining fraction of the activity of the criminal justice system. In 1996, in fact, arson arrests decreased 7 percent after decreasing 3 percent in 1995, increasing 5 percent in 1994, decreasing 1 percent in 1993, and increasing 2 percent in 1992 and 1991. In 1996, arson arrests made up just 0.12 percent of all arrests and just 0.67 percent of all FBI index crime arrests. Of the eight FBI index crimes, which include murder, rape, robbery, aggravated assault, burglary, larceny-theft, motor vehicle theft, and arson, arson nearly always ranks last in number of arrests.

According to FBI statistics, law enforcement agencies have solved, or cleared, between 15 and 19 percent of arson offenses every year since 1980. In 1996, the clearance rate was 16 percent. This rate is much lower than the rate for violent crimes, such as murder, aggravated assault, and rape, but it's on the same order as the clearance rate for other property crimes, such as burglary. Interestingly, the clearance rates for arson, as for all major crimes, tend to be lower in larger cities than they are in smaller cities and rural communities, possibly because people in smaller communities are more likely to know one another, which can make solving a crime easier.

The only alleged perpetrators of 46 percent of all the arsons cases cleared in 1996 were under age 18. This is roughly four times the share of the population between the ages of 10 and 17. It's also the highest percentage of juvenile involvement in any FBI index crime.

The percentage of 1996 arson clearances involving only juveniles was highest-61 percent-for fires involving outdoor trash, brush, and items other than structures and vehicles, and lowest-25 percent-for fires involving vehicles. The rate for structural arson clearances involving only juveniles was 44 percent.

Juveniles also accounted for 53 percent of those arrested for arson in 1996, the third straight year in which the rate was over 50 percent. Nonetheless, arson arrests of juveniles actually decreased 6 percent in 1996, bucking a recent trend toward more arrests among juveniles that reflects both a rise in juvenile arrests and a drop in adult arrests. From 1987 to 1996, there was a 36 percent net increase in arrests of juveniles for arson and a 17 percent decrease in arrests of adults. In 1996, adult arson arrests decreased by 8 percent.

Not only do juveniles make up a large share of all arson arrests, but further analysis shows just how young many of these offenders are. More than one-third of all persons arrested for arson in 1996 were under 15, and roughly one of every 15 persons arrested was under 10 (see Table 5).

Motives, convictions, and sentences

Why do people commit arson? A 1982 USFA report, summarizing the results of several special studies, noted that vandalism and malicious mischief-analogous to what we now describe as juvenile firesetting-and revenge or spite, presumably by adults, were the leading motives cited. Farther back but still significant were pyromania or other mental illness and arson for profit, where profit includes concealment of a crime.

Arson is also used by some drug dealers and gangs as a weapon.(2) A six-month study of five U.S. cities conducted in 1993 found that roughly 22 percent of the arson fires studied were drug-related, with a high degree of consistency across the cities.

These results should be viewed with caution. A full year of data is needed to eliminate seasonal effects, and the five cities may not be representative of other cities, let alone of the entire country. It's also likely that the patterns found wouldn't apply to the same degree to the two-thirds share of the total arson problem that's not coded as incendiary in the field but is left as suspicious or of unknown cause. Even so, the research to date suggests a problem on the order of thousands or tens of thousands of fires per year. That's still a small fraction of the total arson problem, but the number of incidents is large enough, particularly in some cities, to deserve attention.

The U.S. Department of Justice has performed a number of special studies of those convicted of arson that provide useful insights into the arsonist population. According to one done in 1988, 31 percent of state prison inmates whose most serious offense was arson said they were under the influence of illegal drugs when they committed their offenses, and 39 percent said they'd used illegal drugs daily in the month before they committed their offenses.(3) Incarcerated arsonists tend to differ from arsonists in general in that fewer of them are juveniles or first offenders.

Of the 0.7 percent of state prisoners released in 1983 whose most serious offense was arson, 55.3 percent were rearrested for some new crime within three years, 38.5 percent were reconvicted within three years, and 32.3 percent were reincarcerated within three years.(4) All these percentages were considerably lower than the overall recidivism rates and even further below the recidivism rate for other property crimes.

The average sentence served by an arsonist in a state prison is 26 months if it's a first release from prison. Otherwise, the average sentence is 19 months. Half of all arsonists released from prison served 18 months or fewer if it was a first release, 10 months otherwise.

The average length of a federal prison sentence imposed on arsonists in 1990 was 48 months, with half sentenced to 36 months or less.(5) Half of the arsonists released from federal prison had served at least 33 months, which is nearly twice the time served in state prisons. Of course, the sentence served is typically much shorter than the sentence imposed.

According to a study of 178 federal court cases from 1980 to 1989 in which arson was the most serious offense listed for the suspect, the government prosecuted 43 percent of the cases in district court, referred 7 percent to U.S. magistrates, and declined to prosecute 50 percent. A study of 160 arson cases prosecuted and terminated in U.S. district court in the same period found that 66 percent led to convictions and 23 percent were dismissed. Eleven percent of these cases weren't characterized, but they were presumably acquittals.(6)

Put all these studies together, and you begin to get an overall picture of the criminal justice aspects of arson. These characterizations are very rough, particularly because they use statistics from federal and state courts interchangeably, but they reveal a pattern. Of all the set fires that are reported to fire departments-whether they're coded as incendiary, suspicious, or of unknown cause-about one-third are confirmed as incendiary and thus identified as arson. Of these, 80 to 85 percent are never solved or cleared by an arrest. About half of those arrested aren't prosecuted, and about one-third of those prosecuted aren't convicted. Altogether, the percentage of set fires for which someone is convicted is roughly 2 percent. About one-third of those convicted receive no jail or prison time, and the majority of those sent to jail or prison get less than two years. Once released, more than half of those who were incarcerated are rearrested for something, though not necessarily arson, within three years.

The biggest opportunities to change this picture come in the earliest stages, when the fires are investigated to confirm incendiarism and the confirmed arson is investigated to identify and arrest the alleged perpetrators. By the time the district attorneys and courts enter the picture, most set fires have been lost from the system.

What can we conclude?

Arson and suspected arson account for nearly two of every five dollars lost in nonresidential structure fires and are a leading cause of fires and property loss in residential structures, vehicles, and outdoor properties. Fortunately, the largest share of loss due to arson and suspected arson-loss in structures-has declined after adjustment for inflation from its peak in 1980. We've made some progress, but it may not continue without sustained, concentrated effort, and the problem that remains is still far too large. We don't know enough to pinpoint reasons for the trends, but there are four principal factors to consider

First, wider use of sophisticated investigative techniques may be giving a truer picture of fire cause profiles. Since there's little or no evidence to indicate that these techniques are showing that the arson problem was overstated in past years, it's more likely that they would have raised the estimated size of the arson problem and that the measured declines are due to one or more of the other three factors.

Second, wider use of anti-arson programs, like the arson task force approach and counseling for juvenile firesetters, may be producing real reductions in the arson problem. Because these programs are still far from universally used, however, they may explain only part of the trends.

Third, whatever has caused the recent movements in the overall totals of fires in structures may also have caused the trends in the number of incendiary and suspicious structure fires. Both the years of decline and the years of leveling off have been similar for incendiary and suspicious structure fires and all structure fires. From 1979 to 1989, 1991 to 1994, and in 1996, the NFPA survey results showed incendiary and suspicious structure fires fluctuating between 13 and 15 percent of all structure fires, with no clear trend. In 1990 and again in 1995, the numbers jumped to 16 percent, each time indicating that unintentional fires were declining faster than incendiary and suspicious fires in structures.

Finally, there may be trends in the general population that make arson less likely. For example, males aged 10 to 19 constituted 7.2 percent of the population in 1994, compared to 8.9 percent in 1980. This relative decline in the arson-prone age and sex segment could help explain the lower arson rate per 100,000 population, even though the absolute number of people in that segment has increased.

We should be encouraged by the general progress we've made in curtailing arson, but we should also be concerned about the continued loss of life and property that arson causes and skeptical of any simple explanations of our patterns and trends. If we can extend anti-arson programs across the country, arson should decline. We're a long way from controlling arson, but we do have some powerful tools if we use them.

For arson task force or strike force programs, a key is developing interagency organizational arrangements and policies that really work. If arson is to be effectively addressed, police and fire departments need to work together effectively, and other public agencies and private groups should be regularly involved. Of course, there are powerful barriers to such cooperation that can only be overcome if questions about lines of authority, access to financial and informational resources, roles, and ways of operating are addressed explicitly, possibly by following one of the many successful models already in use in several communities across the United States.

If juvenile firesetter counseling programs are to work, we need to become more aware of the many types of juvenile firesetters, to assess the particular circumstances of each firesetter, and to match treatment to those circumstances. For example, children with no significant psychological problems may start fires in the course of an otherwise normal preteen phase of experimenting with their environments. Older juvenile firesetters typically have serious psychological problems, generally traceable to one of several specific types of stresses, including child abuse and learning disabilities. Use of a proven classification scheme can permit effective matching of programs to firesetters.

Finally, we must remember that heightened security is an important element of arson prevention. In most properties, incendiary and suspicious fires are scattered among all the areas of the building, suggesting that security should aim for a greater level of awareness and routine scouting everywhere, not just in a few areas. Security should be especially tight when the building isn't in operation. Utility spaces, such as crawl spaces and attics, are rarely targets, which suggests that arsonists rarely go to extraordinary lengths to conceal their fires. Rather, they set them in places that are used regularly during business hours. Exterior surfaces are popular targets, too, and should be considered in security plans. The diversity of areas of origin of incendiary and suspicious fires also underlines the importance of complete building coverage for fire protection features, such as automatic sprinklers and detection and alarm systems, that mitigate losses when prevention fails.

[Note: the boxed text below appeared as a sidebar]

Definitions and Data Sources Related to Arson An incendiary fire is one which physical evidence or a legal decision indicate was deliberately set by someone capable of understanding the act. While fire departments use the word "incendiary" to describe the cause of a fire, "arson" is the term law enforcement agencies use to describe the crime of deliberately setting a fire. The Uniform Crime Reporting system defines arson as "any willing or malicious burning or attempt to burn, with or without intent to defraud, a dwelling house, public building, motor vehicle or aircraft, personal property of another, etc." Statistics collected by NFPA on incendiary fires and by the FBI on arson track very closely and use closely matched definitions. The major fire databases also identify suspicious fires, which are those for which there's some evidence they were deliberately set but not enough evidence to be conclusive, in the judgment of the investigating officers. NFPA regards the combined total of incendiary and suspicious fires as providing the best measure of the size of the problem of set fires. Finally, there's the class of fires with undetermined cause. For some purposes, it's useful to allocate a share of these fires to the incendiary and suspicious fires, typically a share proportional to their share of all fires whose causes can be determined. Arson may lead to clearances, arrests, and convictions. "Clearance" means the law enforcement officials are satisfied that they've identified the perpetrator, even if no arrest is made. While arrests are the province of law enforcement agencies, convictions are a matter for the courts. No comprehensive national statistics exist on arson convictions. NFPA' survey has the best statistical design of all sources of information on U.S. arson experience, as it's reported to U.S. fire departments. We began using our current methods in 1977, and trends for everything but vehicle fires can be traced to that year; statistics on incendiary and suspicious vehicle fires weren't collected until 1978. The U.S. Fire Administration assembles NFIRS each year from standardized fire incident reports submitted by participating fire departments, which now constitute roughly two-fifths of all U.S. fire departments. NFIRS isn't a statistically designed sample, so it's used in conjunction with the NFPA survey to produce national estimates of specific parts of the fire problem. The FBI's Uniform Crime Reporting system collects standardized crime reports from police departments and some other law enforcement agencies. Agencies protecting roughly 90 percent of the U.S. population submit reports, but those providing reports for the full year cover just over half the U.S. population. The Uniform Crime Reporting system isn't a statistically designed sample, either, and it may be biased by different rates of participation for communities of different sizes. It began including arson statistics in 1980, the first year that arson was designated as a Part I index crime, but some statistics, such as overall arson rates per 100,000 population, weren't computed until 1982, so the statistics shown in this report date back only to 1982.

John R. Hall, Jr., Ph.D., is assistant vice president of NFPA's Fire Research and Analysis Division.

Notes

1. A. Gomberg and L. P. Clark, Rural and Non-Rural Civilian Residential Fire Fatalities in Twelve States, NBSIR-82-2519, Washington: U.S. Department of Commerce, National Bureau of Standards, June 1982.

2. Donna B. Towberman and Thomas J. Towberman, Drug-Related Fires in the United States-A Preliminary Report of Research on the Relationship Between Drug Activity and Arson in Selected U.S. Cities, Project report sponsored by the Bureau of Alcohol, Tobacco and Firearms, Virginia Commonwealth University, Department of Justice and Risk Administration, 1993.

3. Christopher A. Innes, Drug Use and Crime, Washington: Bureau of Justice Statistics, U.S. Department of Justice, July 1988.

4. Allen J. Beck and Bernard E. Shipley, Recidivism of Prisoners Released in 1983, Washington: Bureau of Justice Statistics, U.S. Department of Justice, April 1989.

5. Craig Perkins, National Corrections Reporting Program, 1992, Washington: Bureau of Justice Statistics, U.S. Department of Justice, October 1994.

6. Federal Criminal Case Processing, 1980-87, NCJ-120069, Washington: U.S. Department of Justice, Office of Justice Programs, Bureau of Justice Statistics, May 1990; and Federal Criminal Case Processing, 1980-89, NCJ-130526, October 1991.

Reprinted from NFPA Journal, November/December 1998, p 58-67. Reprinted by permission of NFPA Journal.
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