U.S. Fire Administration/National Fire Data Center

Data Sources and 

Methodology 

Documentation

March 2014
U.S. Fire Administration 

Data Sources and Methodology 

Documentation

DATA SOURCES

The U.S. Fire Administration’s (USFA’s) data analyses are based primarily on the National Fire Incident Reporting System (NFIRS) data, but use other sources as well. Summary numbers for fires, deaths, injuries and dollar 

loss are from the National Fire Protection Association’s (NFPA’s) annual survey of fire departments.1 Other data 

sources used by USFA include 2010 National Center for Health Statistics (NCHS) mortality data2 as compiled 

from data provided by the 57 vital statistics jurisdictions through the Vital Statistics Cooperative Program, 

population estimates from the U.S. Census Bureau, inflation adjustments from the Bureau of Labor Statistics’ 

consumer price index, and state statistics from state fire marshals’ offices or their equivalents are also used. 

Because the NCHS mortality data are based on a census or enumeration of deaths based on death certificates 

rather than an estimate, it is used as the primary source for the computation of fire death rates and relative risk. 

The most current year available for the NCHS mortality data is 2010.3 Please note that for consistency, national 

trend data are based on the NFPA survey estimates, not the NCHS mortality data. 

The USFA gratefully acknowledges the use of the data and information provided by these groups. Data sources 

are cited for each graph and table.

National Fire Incident Reporting System 

The NFIRS was established in 1975 as one of the first programs of the National Fire Prevention and Control 

Administration, which later became the USFA. The basic concept of NFIRS has not changed since the system’s 

inception. All states and all fire departments within them have been invited to participate on a voluntary basis. 

Participating fire departments collect a common core of information on an incident and any casualties that ensue 

by using a common set of definitions. In a very few departments, the data may be written by hand on paper 

forms; however, the majority of the data are collected electronically through third party software, the NFIRS data 

entry tool, or the reporting department’s own system. Local agencies forward the completed NFIRS modules to 

the state agency responsible for NFIRS data. The state agency combines the information with data from other fire 

departments into a statewide database and then transmits the data to the National Fire Data Center at the USFA. 

Data on individual incidents and casualties are preserved incident by incident at local, state and national levels. 

Once limited to fire incidents only, NFIRS now encompasses all incidents to which the fire department responds: 

fire, Emergency Medical Services (EMS), hazardous materials (hazmat), and the like.

1 The NFPA summary numbers are used for the overall U.S. fire losses; fire losses from vehicle, outside and other fires; and as the 

basis for estimates of residential and nonresidential building fires. The alternative approach for these summary numbers is to use 

the relative percentage of fires (or other loss measures) from NFIRS and scale up (multiply by) the NFPA estimate of total fires. The 

results would be somewhat different from those using the NFPA subtotals. These differences are discussed in the section Differences 

Between NFIRS Data and NFPA Survey Data at the end of this document. Better estimates of fire-loss measures from NFIRS will not 

be available until a more robust method of estimation is developed.

2 The NCHS data provide additional detail not available from the NFPA survey: state of fire death occurrence, age, gender and race.

3 The 2011 NCHS data were not available at the time the analyses were undertaken; the 2010 NCHS mortality data were released 

in 2012. As a result, the fire incident and fire injury analyses from NFIRS focus on 2011 while the fire death analyses are from 2010. 

As well, 10-year trends for the NCHS data are from 2001 to 2010 rather than the 2002 to 2011 trend data from NFPA and NFIRS.
Fire in the United States 2

From an initial six states in 1976, NFIRS has grown in both participation and use. Over the life of the system, 

all 50 states, the District of Columbia, and more than 40 major metropolitan areas have reported to NFIRS. As 

well, more than 30,000 fire departments have been assigned participating NFIRS fire department identification 

(FDID) numbers by their states. Approximately 1 million fire incident records and 21 million nonfire incident 

records are added to the database each year. NFIRS is the world’s largest collection of incidents to which fire 

departments respond. 

Between 1985 and 1999, the level of participation remained relatively constant: A few states came in or left the 

system each year, and at least 39 states reported to NFIRS. Most years also included participation from the District of Columbia. The number of fire departments participating within the states remained relatively constant 

as well, with a slight dip in participation during the system migration from version 4.1 to 5.0 in 1999. In 2000, 

the number of states increased to 43, and fire department participation began to bounce back from the version 

5.0 transition low. Since 2000, state and fire department participation has been steadily increasing. In 2003, 

NFIRS reached a milestone with participation by all 50 states. The following year, NFIRS achieved another significant goal: NFIRS not only achieved the national goal of 100 percent state participation, including the District 

of Columbia, but also for the first time, the Native American Tribal Authorities submitted data. 

NFIRS continues to grow and mature. As of 2007, a new level of participation had been achieved: all 50 states, 

the District of Columbia, Native American Tribal Authorities, Northern Mariana Islands, and Puerto Rico all 

participated in NFIRS for a total of 54 state, district, tribal authority, and commonwealth entities (Table 1). 

However, the Mariana Islands and Puerto Rico are no longer reporting incident data to NFIRS. Fire departments 

reporting fire incidents grew to 20,680 in 2011 (Figure 1). Across participating entities, 69 percent of U.S. fire 

departments reported fire incidents to NFIRS in 2011.4

 With over two-thirds of all fire departments nationwide 

reporting fire incidents to NFIRS 5.0, the reporting departments represent a very large dataset that enables USFA 

to make reasonable estimates of various facets of the fire problem. Although some states do require their departments to participate in the state system, participation in NFIRS is voluntary. Additionally, if a fire department is 

a recipient of a Fire Act Grant, participation is required5

.

Table 1. States Reporting Fire Incidents to NFIRS (2002-2011)

State 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

Alabama X X X X X X X X X X

Alaska X X X X X X X X X X

Arizona X X X X X X X X X X

Arkansas X X X X X X X X X X

California X X X X X X X X X X

Colorado X X X X X X X X X X

Connecticut X X X X X X X X X X

Delaware X X X X X X X X X X

District of Columbia X X X X X X

Florida X X X X X X X X X X

Georgia X X X X X X X X X X

Hawaii X X X X X X X X X X

Idaho X X X X X X X X X X

Illinois X X X X X X X X X X

4 For 2011, NFPA estimated that there were 30,145 fire departments in the U.S. Source: NFPA, U.S. Fire Department Profile 

Through 2011, http://www.nfpa.org/assets/files//PDF/OS.FDProfile.pdf, October 2012.

5 From the Assistance to Firefighters Grant Guidance and Application Kit (June 2012), if the applicant is a fire department, the department must agree to provide information, through established reporting channels, to NFIRS for the period covered by the assistance. If 

a fire department does not currently participate in the incident reporting system and does not have the capacity to report at the time of 

the award, the department must agree to provide information to the system for a 12-month period that begins as soon as the department 

develops the capacity to report. See http://www.fema.gov/library/viewRecord.do?id=6007 (fg_2012_afg_program_guidance.pdf).
Fire in the United States 3

Table 1. States Reporting Fire Incidents to NFIRS (2002-2011) - continued

State 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

Indiana X X X X X X X X X X

Iowa X X X X X X X X X X

Kansas X X X X X X X X X X

Kentucky X X X X X X X X X X

Louisiana X X X X X X X X X X

Maine X X X X X X X X X X

Maryland X X X X X X X X X X

Massachusetts X X X X X X X X X X

Michigan X X X X X X X X X X

Minnesota X X X X X X X X X X

Mississippi X X X X X X X X X X

Missouri X X X X X X X X X X

Montana X X X X X X X X X X

Nebraska X X X X X X X X X X

Nevada X X X X X X X X X X

New Hampshire X X X X X X X X X X

New Jersey X X X X X X X X X X

New Mexico X X X X X X X X X X

New York X X X X X X X X X X

North Carolina X X X X X X X X X X

North Dakota X X X X X X X X X X

Ohio X X X X X X X X X X

Oklahoma X X X X X X X X X X

Oregon X X X X X X X X X X

Pennsylvania X X X X X X X X X X

Rhode Island X X X X X X X X

South Carolina X X X X X X X X X X

South Dakota X X X X X X X X X X

Tennessee X X X X X X X X X X

Texas X X X X X X X X X X

Utah X X X X X X X X X X

Vermont X X X X X X X X X X

Virginia X X X X X X X X X X

Washington X X X X X X X X X X

West Virginia X X X X X X X X X X

Wisconsin X X X X X X X X X X

Wyoming X X X X X X X X X X

Native American X X X X X X X X

Northern Mariana Islands X X

Puerto Rico X X X * *

Total 49 50 52 52 53 54 51 52 52 52

Source: NFIRS.

Note:	 Includes fire incidents submitted in both NFIRS versions 4.1 and 5.0 for 2002-2008. Beginning in 2009, includes only fire

incidents submitted in NFIRS version 5.0.

* Puerto Rico submitted fire incident data to NFIRS in 2008-2009, but the data were excluded from all fire data analyses due to data

quality issues.
Fire in the United States 4

Figure 1. NFIRS Fire Department Participation 

(1980-2011, fire incidents only)

0

5,000

10,000

15,000

20,000

25,000

1980

1981

19821983

1984

19851986

1987

198819891990

1991

19921993

1994

19951996

1997

19981999

2000

2001

20022003

2004

20052006

2007

20082009

2010

2011

Number of Participating Fire Departments

Source: NFIRS.

Note:	 1999-2008 includes participation from NFIRS 4.1 and NFIRS 5.0.; 2009 and later includes participation only

from NFIRS 5.0.

Table 2. Fire Departments Reporting Fire Incidents to NFIRS in 2011

State

No. of 

Fire Departments 

in State

No. of Reporting 

Fire Departments 

(NFIRS 5.0)

Percent of Reporting

Fire Departments 

(NFIRS 5.0)

Alabama 1,230 324 26%

Alaska 235 111 47%

Arizona 314 80 25%

Arkansas 976 656 67%

California 1,105 453 41%

Colorado 385 249 65%

Connecticut 260 219 84%

Delaware 61 59 97%

District of Columbia 1 1 100%

Florida 573 437 76%

Georgia 626 311 50%

Hawaii 6 4 67%

Idaho 246 150 61%

Illinois 1,203 1,036 86%

Indiana 829 675 81%

Iowa 848 395 47%

Kansas 577 403 70%

Kentucky 852 552 65%

Louisiana 556 387 70%

Maine 405 163 40%

Maryland 419 263 63%
Fire in the United States 5

Table 2. Fire Departments Reporting Fire Incidents to NFIRS in 2011 - continued

State

No. of 

Fire Departments 

in State

No. of Reporting 

Fire Departments 

(NFIRS 5.0)

Percent of Reporting

Fire Departments 

(NFIRS 5.0)

Massachusetts 366 337 92%

Michigan 1,306 844 65%

Minnesota 784 722 92%

Mississippi 752 709 94%

Missouri 891 465 52%

Montana 392 169 43%

Nebraska 476 177 37%

Nevada 165 42 25%

New Hampshire 232 194 84%

New Jersey 740 653 88%

New Mexico 362 296 82%

New York 1,786 1,128 63%

North Carolina 1,257 1,038 83%

North Dakota 372 151 41%

Ohio 1,208 1,181 98%

Oklahoma 926 385 42%

Oregon 316 231 73%

Pennsylvania 2,287 700 31%

Rhode Island 76 36 47%

South Carolina 435 349 80%

South Dakota 337 191 57%

Tennessee 728 593 81%

Texas 2,025 996 49%

Utah 273 131 48%

Vermont 236 180 76%

Virginia 652 477 73%

Washington 487 323 66%

West Virginia 442 434 98%

Wisconsin 850 550 65%

Wyoming 145 64 44%

Native American 100 6 6%

Total 33,111* 20,680 62%

Sources:	 NFIRS (2011) and state fire marshal’s offices or equivalent organizations (September 2013).

Note:	 Additionally, there are 672 Department of Defense fire departments in the U.S. These departments are not included in the

totals here and do not report their fire incident data to NFIRS.

* This total differs from the 2011 NFPA estimate of 30,145 fire departments. The NFPA estimate is the official estimate used by USFA

as its benchmark for the National Fire Department Census.

Corresponding to increased participation, the numbers of fires, deaths and injuries, as well as estimates of dollar loss reported to NFIRS, also have grown; an estimated 71 percent of all U.S. fires to which fire departments 

responded in 2011 were captured in NFIRS. 
Fire in the United States 6

There are, of course, many problems in assembling a real-world database, and NFIRS is no exception. Although 

NFIRS does not represent 100 percent of incidents reported to fire departments each year, the enormous dataset 

and good efforts by the fire service result in a huge amount of useful information. Because of advances in computer technology and data collection techniques over the past 35 years and improvements suggested by participants, NFIRS has been revised periodically. The newest revision, NFIRS 5.0, became operational in January 1999.

NFIRS 5.0 captures information on all incidents, not just fires, to which a fire department responds. In addition 

to many data coding improvements, version 5.0 provides 11 modules that recognize the increasingly diverse 

activities of fire departments today. These modules, together, contain 567 data elements or fields.

The Basic Module is the main module, which is completed for every incident. The other modules are filled out, 

when appropriate, to provide additional information on an incident. All 11 modules are listed below:

Module Description

Basic Module General information for each incident

Fire Module Fire incident information 

Structure Fire Module Information on structure fires

Civilian Fire Casualty Module Fire-related injuries or deaths to civilians

Fire Service Casualty Module Injuries or deaths to firefighters

EMS Module Medical incidents

Hazardous Materials Module Hazardous materials incidents

Wildland Fire Module Wildland or vegetation fires

Apparatus/Resources Module Apparatus-specific information

Personnel Module Personnel associated with apparatus 

Arson Module Intentionally set fire information

Data from the modules are grouped together each calendar year to create the Public Data Release (PDR) files in 

delimited text (.txt) format that are then released annually into the public domain. For NFIRS data submitted 

prior to 2012, the PDR files were released in dBASE format. The Apparatus/Resources and Personnel Modules 

are excluded from the PDR because they are intended for local fire department use, and the PDR dataset’s main 

utility is intended for national analyses. The PDR files consist of a subset of the data fields contained within the 

NFIRS national production database. For example, data elements with sensitive or identifying information are 

removed as are data elements that are wholly used for maintenance or production purposes. The PDR files’ data 

structure has been considerably simplified from the production database’s schema for ease of use. The PDR files 

from 2004 to the present only include fire and hazmat incidents and their related data tables. Prior to 2004, all 

incidents were included in the PDR files.

In its basic form, the NFIRS PDR files have a relational data structure where data from each incident module 

is represented by a row in a data table. The primary tables (basic incident and incident address) contain most 

of the Basic Module data. There is exactly one record in the basic incident table for every incident reported 

to NFIRS. All other modules, represented by data tables with similar names (fire incident, civilian casualties, 

etc.), have records that are linked to the basic incident table through unique incident identification key fields 

(e.g., STATE, FDID, INC_DATE, INC_NO, and EXP_NO). Some module data are split across several tables (e.g., 

basic incident, incident address, and basic aid tables); one table (fire incident) combines data from two modules 

(i.e., Fire Module and Structure Fire Module). Some tables, such as fire incident, will only have one record for 

each relevant incident in the basic incident table, while tables such as civilian casualty may have several records 

linked to a single incident in the case where multiple injuries and/or deaths occur in the same incident. 

The Basic Module and Fire Module of NFIRS 5.0 collect data in a different fashion than the precursor NFIRS 

systems. The design of NFIRS 5.0 makes the system easier to use than previous NFIRS versions because it captures only the data required to profile the extent of the incident. Some fires, for example, require just basic 

information to be recorded, whereas others require considerably more detail.
Fire in the United States 7

State participation is voluntary, and each state specifies NFIRS reporting requirements for its fire departments. 

States have the flexibility to adapt their state reporting systems to their specific needs. As a result, the design of 

a state’s data collection system varies from state to state. NFIRS 5.0 was designed so that data from state systems 

can be converted to a single format that is used at the national level to aggregate and store NFIRS data.

One of the most important changes is in the data format itself. All data in the system, regardless of the entry 

mechanism, are in NFIRS 5.0 format; non-NFIRS 5.0 data are converted to the 5.0 format. The proportion of 

native 5.0 data has steadily increased since the introduction of NFIRS 5.0 in 1999 (Table 3). This proportion 

rose to 99 percent in the 2008 data. Since Jan. 1, 2009, NFIRS 4.1 data are no longer accepted by the system. 

Prior to 2009, NFIRS 4.1 data in its converted form had been accepted by the system; however, USFA only uses 

native 5.0 data in its NFIRS-based analyses. 

Table 3. NFIRS Fire Incident Data Reporting by Version 

(percent)

Year NFIRS 4.1 

(converted to 5.0 format) Native NFIRS 5.0

1999 92% 8%

2000 77% 23%

2001 48% 52%

2002 31% 69%

2003 19% 81%

2004 11% 89%

2005 5% 95%

2006 5% 95%

2007 2% 98%

2008 1% 99%

2009 0% 100%

Source: NFIRS.

NFIRS Enhancements

Under the USFA Reauthorization Act of 2008, the U.S. Congress authorized and funded USFA to develop enhancements to NFIRS. The upgrades to the system began in October 2008 and included a simplified NFIRS 

Web-based reporting interface and a data warehouse for generating output reports for use in analyses. These 

improvements make reporting and accessing the NFIRS data much easier for fire departments.

In July 2010, USFA completed and deployed the new Web-based data entry tool. The Data Entry Browser Interface (DEBI) is a one-purpose tool for use by the fire service to document incident information within NFIRS. 

While the functionality is the same as the NFIRS client Data Entry Tool that has been available for use for many 

years, DEBI allows entry of incidents using a standard Web browser, eliminating the need to download, install 

and configure client software.

The development of a flexible NFIRS data warehouse with comprehensive data mining capabilities was completed in July 2011. It is scheduled for deployment to national, state and fire department NFIRS users in three 

phases beginning in winter, 2014. The data warehouse will allow NFIRS users to access and report on nationally 

collected data with significantly increased functionality over the current report generation tool. The data have 

been transformed into a custom schema that greatly increases the speed of report generation and data access. 

NFIRS users will be able to generate reports using data from other departments and states, which was not previously possible. More detailed information regarding the NFIRS enhancements is available at http://www.usfa.

fema.gov/fireservice/nfirs/enhancements/.
Fire in the United States 8

NFIRS Training

USFA offers several NFIRS training courses for fire departments that include the “NFIRS Program Management” 

course, “Introduction to NFIRS Self-Study,” and the “Introduction to NFIRS 5.0” course. The “NFIRS Program 

Management” course enables participants to promote, support and manage NFIRS data collection successfully. 

The “Introduction to NFIRS Self-Study” (online) course provides an overview of the data collection system, its 

modules, and data conversion issues. The “Introduction to NFIRS 5.0” course emphasizes how to use standardized forms to achieve uniformity in incident and activity reporting. This training program is designed specifically to support local fire service organizations and assists them in providing data both to management and 

decision-makers, as well as to the state uniform fire reporting system. For more information on NFIRS training 

courses, visit http://www.usfa.fema.gov/fireservice/nfirs/training/. Additionally, USFA’s NFIRS Support Center 

offers a consolidated national help desk to provide technical support to fire departments and NFIRS State Program Managers regarding all aspects of NFIRS. 

Uses of NFIRS

NFIRS data are used extensively at all levels of government for major fire protection decisions. At the local level, 

incident and casualty information is used for setting priorities and targeting resources. The data collected are 

particularly useful for designing fire prevention and educational programs and EMS-related activities specifically 

suited to the real emergency problems local communities face.

At the state level, NFIRS is used in many capacities. One valuable contribution is that some state legislatures use 

these data to justify budgets and to pass important bills on fire-related issues such as sprinklers, fireworks and 

arson. Many federal agencies, in addition to USFA, make use of NFIRS data. NFIRS data are used, for example, 

by the Consumer Product Safety Commission (CPSC) to identify problem products and to monitor corrective 

actions. The Department of Transportation uses NFIRS data to identify fire problems in automobiles, which has 

resulted in mandated recalls. The Department of Housing and Urban Development uses NFIRS to evaluate safety 

of manufactured housing (mobile homes). The USFA uses the data to design prevention programs, to order firefighter safety priorities, to assist in the development of training courses at the National Fire Academy, and for 

a host of other purposes. Thousands of fire departments, scores of states, and hundreds of industries have used 

the data. The potential for even greater use remains. The USFA report, Uses of NFIRS: The Many Uses of the 

National Fire Incident Reporting System, further describes the uses of the data and is available online at http://

www.usfa.fema.gov/downloads/pdf/publications/nfirsuse.pdf.

U.S. Fire Departments

The number of fire departments in each state (Table 2) was provided by each state’s NFIRS Program Manager. 

The USFA also maintains a database of fire departments. The USFA established the National Fire Department 

Census and its subsequent database in the fall of 2001 when the USFA launched a nationwide campaign for 

voluntary registration of fire departments. Over 26,500 fire departments have registered with the census, about 

88 percent of the estimated number of U.S. fire departments. The NFPA estimated that there were 30,145 fire 

departments in the U.S. in 2011.

The census database is intended for use by the fire protection and prevention communities, allied professions, 

the general public, and the USFA. USFA uses the database to conduct special studies, guide program decisionmaking, and improve direct communication with individual fire departments. The database provides a current 

directory of registered fire departments and includes basic information such as addresses, department types, 

website addresses (if applicable), number of fire department personnel, and number of stations. Populationprotected and area-protected data are also collected. However, in previous analyses of the population-protected 

field, it was determined that the fire departments registered with the census reported protecting a population 

two times that of the U.S. population estimated by the U.S. Census Bureau. Similar results were seen for the area 

protected. The National Fire Department Census also collects information on specialized services that is released 

only in summary format. For more information about the National Fire Department Census or to download the 

list of registered fire departments, visit http://apps.usfa.fema.gov/census/.
Fire in the United States 9

METHODOLOGY

An attempt has been made to keep the data presentation and analysis as straightforward as possible. It is also the 

desire of the USFA to make the data analyses widely accessible to many different users, so it avoids unnecessarily complex methodology. The term fire casualties refers to deaths and injuries; the term fire losses collectively 

includes fire casualties and dollar loss.

Analytic Issues and Considerations

There are several longstanding issues regarding how to analyze NFIRS data when it is neither as complete nor as 

accurate as desired. Other analytic issues are the result of changes in definitions and data collection procedures 

from NFIRS 4.1 to NFIRS 5.0. The sections below discuss how the analyses address these and other issues.

National Estimates

National estimates are estimates of the numbers of fire losses (i.e., fires, deaths, injuries and dollar loss) associated with a subset of the fire data. High-level summary national estimates of the numbers for fires, deaths, 

injuries and dollar loss are based on NFPA’s annual Survey of Fire Departments for U.S. Fire Experience.6 With 

the exception of the NFPA estimates for total fires, structure (i.e., residential and nonresidential) fires, vehicle, 

outside and other fires, all other estimates are scaled-up national estimates or percentages, not just the raw totals 

from NFIRS. Because the NFIRS 5.0 data are not based on a statistically selected sample and do not represent a 

“complete” census of fire incidents, the raw counts of NFIRS data must be scaled up to national estimates. These 

estimates are based on a method of apportioning the NFPA estimates for total fires, structure fires, vehicle, outside and other fires.7

 Generally speaking, the national estimates are derived by computing a percentage of fires, 

deaths, injuries or dollar loss in a particular NFIRS category and multiplying it by the corresponding total estimate from the NFPA annual survey.8

 For example, the national estimate for the number of injuries by age group 

used in the calculation for the fire injury rate per million population was computed by taking the percentage 

of NFIRS fire injuries (with known age) and multiplying it by the estimated total number of fire injuries from 

the NFPA survey. This methodology is the accepted practice of national fire data analysts. 

Ideally, one would like to have all of the data come from one consistent data source. Because the “residential 

population protected” is not reported to NFIRS by many fire departments and the reliability of that data element is suspect in many other cases, especially where a county or other jurisdiction is served by several fire 

departments that each report their population protected independently, this data element was not used. Instead, 

extrapolations of the NFIRS sample to national estimates are made using the NFPA survey for the gross totals of 

fires, deaths, injuries and dollar loss.

One problem with this approach is that the proportions of fires and fire losses differ between the large NFIRS 

sample and the NFPA survey sample. Nonetheless, to be consistent with approaches being used by other fire 

data analysts, the NFPA estimates of fires, deaths, injuries and dollar loss are used as a starting point. The details of the fire problem below this level are based on proportions from NFIRS. Because the proportions of fires 

and fire losses differ between NFIRS and the NFPA estimates, from time to time, this approach leads to minor 

inconsistencies. These inconsistencies will remain until all estimates can be derived from NFIRS data alone.

6 For information on NFPA’s survey methodology, please see NFPA’s report on Fire Loss in the United States: http://www.nfpa.

org/~/media/Files/Research/NFPA%20reports/Overall%20Fire%20Statistics/osfireloss.pdf.

7 National estimates are based on “The National Estimates Approach to U.S. Fire Statistics” by Hall and Harwood: http://www.

nfpa.org/assets/files/PDF/Research/Nationalestimates.pdf.

8 The NFPA summary estimates are used for the overall U.S. fire losses; fire losses from structure, vehicle, outside and other fires; and 

as the basis for USFA’s estimates of residential and nonresidential building fires. The alternative approach for these summary numbers is 

to use the relative percentage of fires (or other loss measures) from NFIRS and scale up (multiply by) the NFPA estimate of total fires.
Fire in the United States 10

Structures Versus Buildings

NFIRS 5.0 allows for the differentiation between buildings and nonbuildings. In NFIRS, a structure is a built 

object and can include platforms, tents, connective structures (e.g., bridges, fences), telephone poles, and various other structures in addition to buildings. Analyses of NFIRS structure fires show that, by and large, the 

majority (93 percent) of structure fires occurs in buildings.

The distinction between buildings and nonbuildings is particularly important when determining the effectiveness of nonbehavior-based fire safety mechanisms such as smoke alarms and residential sprinklers. These 

important components of early fire detection apply to buildings and not necessarily to these other types of 

structures. To facilitate analysis of these components and to acknowledge that prevention efforts generally are 

centered on buildings, USFA separates buildings from the rest of the structures. For these reasons, USFA focuses on producing building fire and loss estimates. USFA’s Fire Estimate Summary Series as well as 2003-2011 

national estimates of residential and nonresidential building fires and losses are published at http://www.usfa.

fema.gov/statistics/estimates/index.shtm. For information on USFA’s methodology for computing national estimates of residential and nonresidential building fires and losses, please review USFA’s National Estimates Methodology for Building Fires and Losses (August 2012) at http://www.usfa.fema.gov/downloads/pdf/statistics/

national_estimate_ methodology.pdf.

Unknown Entries

On a fraction of the incident reports or casualty reports sent to NFIRS, the desired information for many data 

items either is not reported or is reported as “unknown.” The total number of blank or unknown entries is often larger than some of the important subcategories. For example, 46 percent of fatal fires in residential buildings reported from 2009-2011 do not have sufficient data recorded in NFIRS to determine fire cause.9

 The lack 

of data, especially for these residential fatal fires, masks the true picture of the fire problem. Many prevention 

and public education programs use NFIRS data to target at-risk groups or to address critical problems, fire officials use the data in decision-making that affects the allocation of firefighting resources, and consumer groups 

and litigators use the data to assess product fire incidence. When the unknowns are large, the credibility of the 

data suffers. In some cases, even after the best attempts by fire investigators, the information is truly unknown. 

In other cases, the information reported as unknown in the initial NFIRS report is not updated after the fire 

investigation is completed. Fire departments need to be more aware of the effect of incomplete data reporting 

and need to update the initial NFIRS report if additional information is available after investigation. 

In making national estimates, the unknowns should not be ignored. The approach taken by USFA in presenting the data is to provide not only the “raw” percentages of each category but also the “adjusted” percentages 

computed using only those incidents for which data were provided. This calculation, in effect, distributes the 

fires for which the data are unknown in the same proportion as the fires for which the data are known, which 

may or may not be approximately right. 

To illustrate, using the cause of residential building fires, cooking was determined as the fire cause for 37.3 

percent of reported residential building fires in 2011; another 18.4 percent of reported fires had cause unknown. 

Thus, the percent of fires that had their cause reported was 100 minus 18.4 equals 81.6 percent. With the unknown causes proportioned like the known causes, the adjusted percent of cooking fires in residential buildings 

can then be computed as 37.3 divided by 81.6 equals 45.7 percent.

Both the reported data and the adjusted data (if unknowns are present) are plotted on bar charts.

9 USFA, Topical Fire Report Series, “Fatal Fires in Residential Buildings (2009-2011),” Volume 14, Issue 3, May 2013 (http://www.

usfa.fema.gov/downloads/pdf/statistics/v14i3.pdf).
Fire in the United States 11

Incomplete Loss Reporting

As troublesome as insufficient data for the various NFIRS data items can be, equally challenging is the apparent 

nonreporting of injuries and property loss associated with many fire incidents. For example, there are many 

reported fires where the flame spread indicates damage but property loss is not reported. It is notoriously difficult to estimate dollar loss, but an approximation is more useful than leaving the data item blank. The degree 

to which there is incomplete reporting of civilian fire deaths is more difficult to identify, as the numbers of 

deaths are relatively small. Incomplete reporting of civilian injuries also is difficult to ascertain, but the injuryper-fire profiles for most departments are within reason.

Representativeness of the Sample

The percentage of fire departments participating in NFIRS varies from state to state, with some states not participating at all in some years. To the best that USFA can determine, the distribution of participants is reasonably 

representative of the entire nation, even though the sample is not random. The dataset is so large — on average 

about 65 percent of all fires — and reasonably distributed geographically and by size of community that it is 

used as input to develop national estimates. 

In a joint study effort, USFA and NFPA examined the biases in NFIRS participation, specifically whether the 

fire experience of NFIRS-reporting departments differed systematically from the fire experience of other nonreporting departments within the same population. Results based on data from 1997 and 2002 indicated that 

there were differences in total fire-loss estimates derived from NFIRS reporting departments and non-NFIRS reporting departments; however, the degree of difference was not great enough to merit adjusting current scaling 

methodologies. Thus, USFA and fire data analysts from other organizations continue to use the long-standing 

methodology of scaling NFIRS estimates with NFPA total fire estimates.

In the fall of 2008, as required by the U.S. Office of Management and Budget (OMB), USFA undertook a study of 

the NFIRS dataset to examine the potential bias in NFIRS due to fire department nonresponse. As a result, USFA 

completed an analysis to identify fire departments that do not participate in NFIRS, characteristics of these departments, and whether their nonresponse impacted the representativeness of NFIRS. Undertaken on a regional 

and county basis, the analysis provided insight into what, if any, adjustments could be made to minimize the 

impact of possible reporting bias on the fire-loss estimates. States of particular concern for nonreporting were located in the Northeast and West regions of the country where the average rates of reporting were approximately 

72 percent for each of these regions. By contrast, the Midwest region had an estimated 87 percent reporting rate.

In 2011, USFA also completed a second NFIRS representativeness study as required by OMB. For this study, USFA 

compared the NFIRS database to NFPA proprietary data to determine the percentage of departments responding to the NFPA survey that also reported fires to NFIRS. It was determined that 87 percent of the 2009 NFPA 

survey respondents also reported fire incidents to NFIRS from 2007 to 2009. In 2009 alone, more than 18,000 

additional departments (i.e., in addition to those responding to the NFPA survey) reported fires to NFIRS. 

It is important to note that USFA along with other federal agencies does not use NFIRS data to derive state-level 

fire estimates. NFIRS data are used to show the fire problem at the national level. Because the findings in USFA’s 

latest NFIRS representativeness study show a very high percentage of the NFPA respondents are also reporting 

fires to NFIRS, fire departments across the country appear to be well-represented in NFIRS.

Additionally, most of the NFIRS data exhibit stability from one year to the next, without radical changes. Results 

based on the full dataset are generally similar to those based on part of the data, another indication of data 

reliability. Although improvements could be made — the individual incident reports could and should be filled 

out more completely and more accurately than they are today (as can be said about most real-world data collections as large as NFIRS), and all participating departments should have the same reporting requirements — the 

overall portrayal is a reasonably accurate description of the fire situation in the U.S.

Unreported Fires

NFIRS only includes fires to which the fire service responded. In some states, fires attended by state fire agencies 

(such as forestry) are included; in other states, they are not.
Fire in the United States 12

Nonreporting to NFIRS

NFIRS includes fires from all states but does not include incidents from all fire departments within participating 

states; the percent of fire departments reporting varies greatly from state to state. However, if the fires from the 

reporting departments are reasonably representative, this omission does not cause a problem in making useful 

national estimates for any but the smallest subcategories of data and for some geographic analyses.

Some fire departments submit information on most, but not all, of their fires. Sometimes the confusion is systematic, as when no-loss cooking fires or chimney fires are not reported. Sometimes it is inadvertent, such as 

when incident reports are lost or accidentally not submitted. The information that is received is assumed to be 

the total for the department and is extrapolated as such. Although there was no measure of the extent of this 

problem in the past, the NFIRS 5.0 provides fire departments with the capability to report this information in 

a simplified, more straightforward manner.

Nonreporting to the Fire Service

A very large number of fires are not reported to the fire service at all. Most are believed to be small fires in the 

home or in industry that go out by themselves or are extinguished by the occupant. Special surveys of homes 

and businesses are needed to estimate the unreported fires. No attempt is made here to estimate them. Studies 

undertaken in the mid-1970s, mid-1980s and again in the mid-2000s on unreported residential fires indicated 

that a substantial number of fires are not reported to local fire departments. The 2004-2005 CPSC study on 

unreported residential fires noted that, of the estimated number of fires in residences, only 3 percent were 

reported to fire departments and 97 percent were not.10 Although the vast majority of fire incidents are unreported because they are small, confined and immediately extinguished, they are still fires. Even the largest fire 

starts small. Hence, all fires, regardless of size, merit prevention attention and analytic investigation.

Computing Trends

A frequently asked question is how much a particular aspect of the fire problem has changed over time. The 

usual response is in terms of a percent change from one year to another. As we are dealing with real-world data 

that fluctuate from year to year, a percent change from one specific year to another can be misleading. This 

is especially true when the beginning and ending data points are extremes, either high or low. For example, 

Table 4 shows that the percent change from 9,125 fire injuries in one- and two-family residential buildings in 

2007 to 8,925 fire injuries in 2011 would be a decrease of 2.2 percent; however, if we were to choose 2009 as 

the beginning data point (8,125 fire injuries), this change would show a substantial 9.8 percent increase. As we 

are interested in trends in the U.S. fire problem, USFA presents the computed best-fit linear trend line (which 

smooths fluctuations in the year-to-year data) and presents the change over time based on this trend line. The 

overall five-year trend is a decrease in injuries of 1.3 percent which, in this example, is relatively close to the 

point-to-point change between the five years. As noted above, trends that incorporate NFIRS data from the 5.0 

system may have subtle changes as a result of the system design and not a true trend change.

Table 4. Comparison of Percent Change Indicators

Year

One- and TwoFamily Residential 

Building Fire Injuries

Best-Fit 

Linear Trend

Change Between 

2007 and 2011

Change Between 

2009 and 2011

2007 9,125 8,675 9,125

2008 8,400 8,648

2009 8,125 8,620 8,125

2010 8,525 8,593

2011 8,925 8,565 8,925 8,925

Percent change -1.3% -2.2% 9.8%

Source:	 USFA national estimates of one- and two-family residential building fire injuries.

10 Michael A. Greene and Craig Andres, Division of Hazard Analysis, Directorate for Epidemiology, U.S. Consumer Product Safety 

Commission, 2004-2005 National Sample Survey of Unreported Residential Fires, July 2009.
Fire in the United States 13

Rounding

Percentages on each chart are rounded to one decimal point. Textual discussions cite these percentages as whole 

numbers. Thus, 13.4 percent is rounded to 13 percent and 13.5 percent is rounded to 14 percent. National 

estimates are rounded as follows: Fires are rounded to the nearest 100 fires, deaths to the nearest five deaths, 

injuries to the nearest 25 injuries, and loss to the nearest million dollars.

Comparing Statistics 

Differences between the current NFIRS and older versions have, or may have, an effect on the analyses of fire 

topics. These differences, the result of both coding changes and data element design changes, required revisions 

to long-standing groupings and analyses. The revisions have caused some challenges when comparing current 

data to past data. 

Data Collection and Reporting Changes

Streamlined reporting for qualified incidents, the collection of smoke alarm and automatic extinguishing system 

(AES) data (formerly called sprinklers), definition changes for some property types, the differentiation between 

buildings and structures, and changes in the cause methodology are among the areas that are approached differently in NFIRS 5.0.11 These revisions have resulted in changes in overall trends, some subtle and some substantial. 

Confined Fires

The limited reporting of confined, low-loss structure fires allows the fire service to capture incidents that either 

might have gone unreported prior to the introduction of NFIRS 5.0 or were reported, but as a nonfire incident, 

as no loss was involved.12 Data from this reporting option for structure fires were investigated in a 2006 USFA 

report, Confined Structure Fires. The addition of these fires results in increased proportions of cooking and 

heating fires in analyses of structure fire cause. In other analyses, the inclusion of confined fires may result in 

larger unknowns, as detailed reporting of fire specifics is not required. In many USFA analyses, the confined 

fires are analyzed separately from the nonconfined fires to account for the fact that detailed reporting is not 

required for the confined fires. In 2011, confined fires accounted for 17 percent of all fires and 45 percent of 

structure fires. Eighty-one percent of confined structure fires were no- or low-loss cooking fires (65 percent) 

and heating fires (16 percent).

Definitional Changes

Property Types

Examples of property type changes include manufacturing and properties that are vacant and under construction. 

Manufacturing properties are no longer assigned a specific property use code based on the type of item manufactured. Instead, these properties are differentiated by an additional data element, “on-site materials.” Vacant and 

under construction now is an attribute of a structure and no longer is considered a separate property type.

Buildings and Structures

NFIRS 5.0 allows for the differentiation between buildings and nonbuildings. In NFIRS 5.0, a structure is a 

built object and can include platforms, tents, connective structures (e.g., bridges), and various other structures 

(e.g., fences, underground work areas). This distinction between buildings and nonbuildings is important when 

determining the effectiveness of engineered fire safety features such as smoke alarms and AES. These important 

components of early fire detection and automatic suppression apply to buildings and not necessarily to other 

types of structures. To facilitate analysis of these components and to acknowledge that prevention efforts generally are focused on buildings, USFA separates the subset of buildings from the rest of the structures.

11 Other changes between NFIRS 4.1 and 5.0, such as mutual aid, do not have as significant an impact on analyses. As such, they 

are not addressed here. The NFIRS 5.0 documentation at http://www.nfirs.fema.gov/documentation/ provides detailed information.

12 Some states routinely reported such nonloss fires as smoke scares. The result, from a reporting viewpoint, is that the incident 

is reported, but not coded as a fire incident.
Fire in the United States 14

Structure fires are defined by the NFIRS incident type. Structure fires are defined as the 110 Incident Type Series 

(structure fires) and the 120 Incident Type Series (fires in mobile property used as a fixed structure).13 These 

incident types are:

•	 111 Building fire.

•	 112 Fires in structure other than in a building.14

•	 113 Cooking fire, confined to container.

•	 114 Chimney or flue fire, confined to chimney or flue.

•	 115 Incinerator overload or malfunction, fire confined.

•	 116 Fuel burner/boiler malfunction, fire confined.

•	 117 Commercial compactor fire, confined to rubbish.

•	 118 Trash or rubbish fire, contained.

•	 120 Fire in mobile property used as a fixed structure, other.

•	 121 Fire in mobile home used as fixed residence.

•	 122 Fire in motor home, camper, recreational vehicle.

•	 123 Fire in portable building, fixed location.

Building fires are a subset of structure fires. They are defined as structure fires where the structure type is an 

enclosed building, a fixed portable, or mobile structure. By definition, this excludes nonbuilding structures. 

Previous USFA analyses demonstrated that confined structure fire incidents with full incident reporting primarily occurred in buildings. To accommodate the confined fire incident types with abbreviated incident reporting, the incident is also assumed to be a building if the structure type is not specified. In terms of NFIRS data, 

building fires are therefore defined as:

•	 NFIRS version 5.0 data.

•	 Aid Types: 

- 1 Mutual aid received.

- 2 Automatic aid received.

- 5 Other aid given.

Note: Mutual aid given and automatic aid given (Aid Types 3 and 4) were excluded to avoid double counting of incidents.

•	 Incident Types 111-123 (excluding Incident Type 112):

- 111 Building fire.

- 113 Cooking fire, confined to container.

- 114 Chimney or flue fire, confined to chimney or flue.

- 115 Incinerator overload or malfunction, fire confined.

- 116 Fuel burner/boiler malfunction, fire confined.

- 117 Commercial compactor fire, confined to rubbish.

- 118 Trash or rubbish fire, contained.

- 120 Fire in mobile property used as a fixed structure, other.

- 121 Fire in mobile home used as fixed residence.

- 122 Fire in motor home, camper, recreational vehicle.

- 123 Fire in portable building, fixed location.

Notes: (1) Incident Types 113-118 do not specify if the structure is a building. (2) Incident Type 112 was 

included in data analyses prior to 2008 as previous analyses showed that Incident Types 111 and 112 were 

used interchangeably. As of 2008, Incident Type 112 is excluded.

13 Note that Incident Type 110 is not included. Incident Type 110 is a conversion code for NFIRS 4.1. Incident Type 110 is not a 

valid code for data collected in NFIRS 5.0. Incidents in the NFIRS 5.0 database with a 110 Incident Type are incidents collected under 

the NFIRS 4.1 system and are converted to NFIRS 5.0 compatible data.

14 Preliminary findings noted that the fires coded as 112 appear to be buildings. A more detailed look at these incident types is 

required to determine whether they were coded correctly.
Fire in the United States 15

•	 Structure type:

- For Incident Types 113-118:

– Enclosed building.

– Fixed portable or mobile structure, and structure type not specified (null entry).

- For Incident Types 111 and 120-123:

– 1 Enclosed building.

– 2 Fixed portable or mobile structure.

Structure Fire Cause Methodology

Since the introduction of NFIRS version 5.0, the implementation of the cause hierarchy has resulted in a steady 

increase in the percentages of unknown fire causes. This increase may be due, in part, to the fact that the 

original cause hierarchy (described in “Fire in the United States 1995-2004,” 14th edition) does not apply as 

well to version 5.0. Causal information now collected as part of NFIRS version 5.0 was not incorporated in the 

old hierarchy. As a result, many incidents were assigned to the unknown cause category. As the hierarchy was 

originally designed for structures, incidents that did not fit well into the structure cause categories were also 

assigned to the unknown category. 

Structure Fires

To capture the wealth of data available in NFIRS 5.0, USFA developed a modified version of the previous cause 

hierarchy for structure fires as shown in Table 5. The revised schema provides three levels of cause descriptions: 

a set of more detailed causes (priority cause description), a set of mid-level causes (cause description), and a set 

of high-level causes (general cause description). The priority cause description and the cause description existed 

previously as part of the original cause hierarchy but have been expanded to capture the new 5.0 data. 

Table 5. Three-Level Structure Fire Cause Hierarchy

Priority Cause Description

(in hierarchical order) Cause Description General Cause Description

Exposure Exposure Exposure

Intentional Intentional Firesetting

Cause under investigation Cause under investigation Unknown

Children playing Playing with heat source Firesetting Other playing

Natural Natural Natural

Fireworks

Other heat

Explosives Flame, heat

Smoking Smoking

Heating Heating

Cooking Cooking Equipment

Air conditioning Appliances

Electrical distribution Electrical malfunction Electrical

Appliances Appliances

Special equipment Equipment Other equipment Processing equipment

Torches Open flame Flame, heat

Service equipment

Vehicle, engine Other equipment Equipment

Unclassified fuel-powered equipment
Fire in the United States 16

Table 5. Three-Level Structure Fire Cause Hierarchy - continued

Priority Cause Description

(in hierarchical order) Cause Description General Cause Description

Unclassified equipment with other or 	 	 	 	 	

unknown fuel source Unknown Unknown

Unclassified electrical malfunction 	 	 Electrical malfunction Electrical

Matches, candles	 Open flame	

Flame, heat	

Open fire	

Other open flame, spark 	 	 	 	 Other heat

Friction, hot material 	 	

Ember, rekindle	 Open flame	

Other hot object	 	 Other heat

Natural condition, other 	 	 Natural Natural

Heat source or product misuse Other unintentional, careless Unknown

Equipment operation deficiency 	 	 Equipment misoperation, failure Equipment Equipment failure, malfunction 	 	

Trash, rubbish	 Unknown

Unknown

Other unintentional Other unintentional, careless

Exposure (fire spread, other) 	 	 	 Exposure Exposure

Unknown Unknown Unknown

Source: USFA.

Note:	 Fires are assigned to a cause category in the hierarchical order shown. For example, if the fire is judged to be intentionally set

and a match was used to ignite it, it is classified as intentional and not open flame because intentional is higher on the list.

The causes of fires are often a complex chain of events. To make it easier to grasp the “big picture,” the 16 midlevel categories of fire causes such as heating, cooking and playing with heat source are used by the USFA. The 

alternative is to present scores of detailed cause categories or scenarios, each of which would have a relatively 

small percentage of fires. For example, heating includes subcategories such as misuse of portable space heaters, 

wood stove chimney fires, and fires involving gas central heating systems. Experience has shown that the larger 

categories are useful for an initial presentation of the fire problem. A more detailed analysis can follow.

Fires are assigned to one of the 16 mid-level cause groupings using a hierarchy of definitions, approximately as 

shown in Table 6.15 A fire is included in the highest category into which it fits on the list. If it does not fit the 

top category, then the second one is considered, and if not that one, the third and so on. (See the note section 

in Table 5 for examples.)

Vehicle, Outside and Other Fires

While these new cause categories have usefulness for the other property types — vehicle, outside and other 

fires — there are limitations. USFA plans to investigate and develop specific cause categories for vehicle, outside 

and other fires. Until then, the causes of fires for these property types are based on the distributions of the 

NFIRS cause of ignition data element. This data element captures a very broad sense of the cause of the fire.

Deaths, Injuries and Dollar Loss

In previous analyses, the cause sections have included the distributions of deaths, injuries and dollar loss by 

fire cause. In principle, it is the cause of the fire which results in deaths, injuries and dollar loss that should be 

analyzed, not numbers of deaths and injuries associated with fire causes. Therefore, analyses of fire cause will 

address fires that cause deaths (fatal fires), fires that cause injuries, and fires that cause dollar loss.

15 The structure fire cause hierarchy and specific definitions in terms of the NFIRS 5.0 codes may be found at http://www.usfa.

fema.gov/fireservice/nfirs/tools/fire_cause_category_matrix.shtm. The hierarchy involves a large number of subcategories that are 

later grouped into the 16 mid-level cause categories, then the eight high-level cause groupings.
Fire in the United States 17

Other Considerations

An additional problem to keep in mind when considering the rank order of causes is that sufficient data to categorize the cause were not reported to NFIRS for all fatal fires in the database. The rank order of causes might 

be different than shown here if the cause profile for the fires where causes were not reported to NFIRS were 

substantially different from the profile for the fires where causes were reported. However, there is no information available to indicate that there is a major difference between the known causes and the unknown causes, 

and so our present best estimate of fire causes is based on the distribution of the fires with known causes.

Table 6. Mid-Level Cause Groupings

Cause Category Definition

Exposure Caused by heat spreading from another hostile fire.

Intentional Cause of ignition is intentional or fire is deliberately set.

Cause under investigation Cause is under investigation and a valid NFIRS Arson Module is present. (This 

category was formerly called “Investigation with Arson Module.”)

Playing with heat source

Includes all fires caused by individuals playing with any materials contained in

the categories below as well as fires where the factors contributing to ignition

include playing with heat source. Children playing with fire are included in this

category.

Natural

Caused by the sun’s heat, spontaneous ignition, chemicals, lightning, static discharge, high winds, storms, high water including floods, earthquakes, volcanic

action and animals.

Other heat Includes fireworks, explosives, flame/torch used for lighting, heat or spark from

friction, molten material, hot material, heat from hot or smoldering objects.

Smoking Cigarettes, cigars, pipes and heat from undetermined smoking materials.

Heating

Includes confined chimney or flue fire, fire confined to fuel burner/boiler malfunction, central heating, fixed and portable local heating units, fireplaces and

chimneys, furnaces, boilers, water heaters as source of heat.

Cooking Includes confined cooking fires, stoves, ovens, fixed and portable warming units,

deep fat fryers, open grills as source of heat.

Appliances 

Includes televisions, radios, video equipment, phonographs, dryers, washing

machines, dishwashers, garbage disposals, vacuum cleaners, hand tools, electric blankets, irons, hairdryers, electric razors, can openers, dehumidifiers, heat

pumps, water cooling devices, air conditioners, freezers and refrigeration equipment as source of heat.

Electrical malfunction

Includes electrical distribution, wiring, transformers, meter boxes, power switching gear, outlets, cords, plugs, surge protectors, electric fences, lighting fixtures,

electrical arcing as source of heat.

Other equipment

Includes special equipment (radar, x-ray, computer, telephone, transmitters,

vending machine, office machine, pumps, printing press, gardening tools, agricultural equipment), processing equipment (furnace, kiln, other industrial machines), service, maintenance equipment (incinerator, elevator), separate motor

or generator, vehicle in a structure, unspecified equipment.

Open flame, spark

(heat from)

Includes torches, candles, matches, lighters, open fire, ember, ash, rekindled

fire, backfire from internal combustion engine as source of heat.

Other unintentional,

careless

Includes misuse of material or product, abandoned or discarded materials or

products, heat source too close to combustibles, other unintentional (mechanical failure/malfunction, backfire).

Equipment misoperation,

failure Includes equipment operation deficiency, equipment malfunction.

Unknown Cause of fire undetermined or not reported.

Source: USFA.
Fire in the United States 18

NFIRS fire causal data can be analyzed in many ways, such as by the heat source, equipment involved in ignition, 

factors contributing to ignition, or many other groupings. The hierarchy of causes used has proven to be useful in 

understanding the fire problem and targeting prevention, but other approaches are useful too. Because the NFIRS 

database stores records fire-by-fire, and not just in summary statistics, a wide variety of analyses is possible.

The cause categories displayed in the graphs of USFA’s NFIRS data-related reports are listed in the same order to 

make comparisons easier from one to another. The y-scale varies from figure to figure depending on the largest 

percentage that is shown; the y-scale on a figure with multiple charts, however, is always the same. 

Differences Between NFIRS Data and NFPA Survey Data

As there are differences between any two analysts using NFIRS data because of the many assumptions and decisions about how to analyze incomplete and imperfect data, there can be inconsistencies between different data 

sources. In particular, there are discrepancies between the NFIRS 5.0 data and the NFPA annual survey data. 

NFIRS 5.0 deaths and injuries per 1,000 fires are lower than those of NFPA. With the exception of 2007, NFIRS 

5.0 dollar loss per fire is lower than that of NFPA.16

NFIRS collects fire incident data from an average of 20,320 fire departments each year. NFPA annual survey of 

fire departments17 collects data from nearly 3,000 fire departments. NFIRS is not a statistically selected sample; 

however, it is a very large set of fire incidents — estimated to be, on average, two-thirds of reported fires. The 

NFPA survey is based on a statistical sample. These two datasets often yield dramatically different fire rates. 

The NFPA survey collects tallied totals, whereas NFIRS collects individual incident reports. During the period 

examined, the proportion of native NFIRS 5.0 fire data rose from 98 percent of all NFIRS fire incidents collected 

in 2007 to 100 percent of all NFIRS fire incidents starting in 2009. It is not surprising, therefore, that there 

are differences between the NFPA annual survey results and the NFIRS results. In the years examined (2007 to 

2011), the common thread was the increase in the ratios of NFIRS data to the NFPA estimates. In general, the 

deaths reported to NFIRS represented a smaller fraction of the NFPA national estimate of deaths than the NFIRS 

number of fires was of the NFPA estimate of fires. Estimates of dollar loss are notoriously inexact; it is not surprising that the NFIRS dollar loss changed from year to year with respect to NFPA totals (Figure 2).

Figure 2. Ratio of Raw NFIRS Sample to NFPA National Estimates

Fires Deaths Injuries Dollar 

Loss

2007 0.63 0.55 0.53 0.64

2008 0.64 0.59 0.57 0.62

2009 0.67 0.61 0.56 0.57

2010 0.73 0.63 0.59 0.61

2011 0.71 0.67 0.60 0.70

Sources: NFPA and NFIRS.

Note:	 The 2007 dollar loss excludes the one-time large

loss of an estimated $1.8 billion associated with

the 2007 California Fire Storm. The 2008 dollar

loss excludes the one-time large loss of an estimated $1.4 billion associated with the 2008

California Wildfires. These losses do not have associated property uses.

Looking at the problem from a different perspective, Figure 3 shows the number of deaths per 1,000 fires, injuries 

per 1,000 fires, and dollar loss per fire from NFIRS and NFPA from 2007 to 2011. In general, deaths and injuries 

per 1,000 fires and dollar loss per fire were lower for NFIRS than for NFPA. This difference may be the result of 

more low-loss fires being reported to NFIRS as a result of the abbreviated reporting option for these fires. 

16 As NFIRS 5.0 now captures a large number of small, low-loss fires (confined fires) thought to be unreported previously, these 

differences in loss rates per fire may not be surprising.

17 “Fire Loss in the United States,” NFPA Journal, generally the September/October issue each year.

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

Fires

Deaths

Injuries

Dollar Loss

2007 2008 2009 2010 2011

Ratio
Fire in the United States 19

Between 2007 and 2011 NFIRS had, on average, a difference of 10 percent fewer fire deaths per 1,000 fires than 

the NFPA survey data. Annually, the NFIRS percentage differences of fire deaths per 1,000 fires ranged from 6 

to 14 percent lower than that of NFPA. In 2011, NFIRS showed only 6 percent fewer fire deaths per 1,000 fires 

than NFPA. 

Injuries per 1,000 fires revealed a much greater disparity between the two datasets. On average, between 2007 

and 2011, NFIRS had a difference of 16 percent fewer fire injuries per 1,000 fires than the NFPA survey.

On average over the five-year period, the NFIRS dollar loss per fire was 7 percent lower than that of the NFPA 

survey. In 2008 and 2011, NFIRS dollar loss was only 3 percent and 2 percent lower, respectively, than the dollar-loss estimates from the NFPA survey but revealed a much greater disparity in 2009 (15 percent) and 2010 (17 

percent). In 2007, more dollar loss was reported to NFIRS per fire than that reflected in the NFPA survey data.

Figure 3. NFIRS Versus NFPA Survey: Losses per Fire

1.6

1.8

2.0

2.2

2.4

2.6

NFPA

NFIRS

2007 2008 2009 2010 2011

Deaths (per 1,000 Fires)

9.0

9.4

9.8

10.2

10.6

11.0

11.4

11.8

12.2

12.6

13.0

13.4

NFPA

NFIRS

2007 2008 2009 2010 2011

Injuries (per 1,000 Fires)

$7,000

$7,500

$8,000

$8,500

$9,000

$9,500

$10,000

$10,500

$11,000

$11,500

NFIRS

NFPA

2007 2008 2009 2010 2011

Dollar Loss (per Fire) Adjusted to 2011 Dollars

Deaths (per 1,000 Fires)

Year NFIRS NFPA

2007 1.92 2.20

2008 2.13 2.29

2009 2.04 2.23

2010 2.02 2.34

2011 2.04 2.16

Injuries (per 1,000 Fires)

Year NFIRS NFPA

2007 9.52 11.35

2008 10.30 11.51

2009 10.65 12.64

2010 10.61 13.31

2011 10.59 12.59

 Dollar Loss (per Fire)* 

* Adjusted to 2011 Dollars

Year NFIRS NFPA

2007 9,092 8,943

2008 9,794 10,133

2009 8,294 9,743

2010 7,480 8,982

2011 8,244 8,391

Sources:	 NFPA, NFIRS and consumer price index.

Note:	 The 2007 dollar loss excludes the one-time large loss of an estimated $1.8 billion associated with the 2007 California Fire

Storm. The 2008 dollar loss excludes the one-time large loss of an estimated $1.4 billion associated with the 2008 California Wildfires. These losses do not have associated property uses.
Fire in the United States 20

Other minor differences appear when reviewing losses by property type as shown in Figure 4. Specifically, the 

distributions of fires across property types between NFIRS and NFPA were quite similar, which is reassuring. 

Over the five-year period, the proportions of structure fires (both residential and nonresidential) and outside 

and other fires were slightly higher in the NFIRS sample while the proportion of vehicle fires was slightly more 

represented in the NFPA estimate. Regardless of the specifics, the distributions were reasonably comparable.

Figure 4. Comparison of NFIRS Data with NFPA Estimates by Incident Type 

(5-year average, 2007-2011)

0.0 10.0 20.0 30.0 40.0 50.0 60.0

NFPA

NFIRS

Outside and

other

Vehicle

Nonresidential

Residential

0.0 20.0 40.0 60.0 80.0 100.0

NFPA

NFIRS

Outside and

other

Vehicle

Nonresidential

Residential

Fires

Percent

Deaths

Percent

0.0 20.0 40.0 60.0 80.0 100.0

NFPA

NFIRS

Outside and

other

Vehicle

Nonresidential

Residential

0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0

NFPA

NFIRS

Outside and

other

Vehicle

Nonresidential

Residential

Injuries

Percent

Dollar Loss (Adjusted to 2011 Dollars)

Percent

28.7

27.7

8.0

7.5

14.0

16.2

49.3

48.6

76.1

84.9

3.8

3.2

15.8

10.3

4.2

1.6

78.0

79.4

7.8

7.8

3.9

8.5

6.3

8.2

60.6

55.6

25.0

24.3

10.6

11.1

8.9

3.9

Sources: NFPA and NFIRS.

The deaths, injuries and dollar losses that result from these fires were consistently more heavily represented in 

residential structures in the NFPA estimates. For the other major property categories (except vehicular fire injuries and dollar loss and nonresidential structure fire injuries), the NFPA percentages of losses are consistently 

less than those resulting from NFIRS data.

One of the more important consequences of these distributions is in the creation of estimates of the various parts 

of the U.S. fire problem. For example, it is noted that the 2011 NFPA residential structure fire estimates reflect 

85 percent of fire deaths (2,550 of 3,005) and 82 percent of fire injuries (14,360 of 17,500). If the 2011 NFIRS 

percentages for deaths (76 percent) and injuries (79 percent) were applied to the overall 2011 NFPA estimates, 

the estimates would yield approximately 2,275 deaths and 13,850 injuries, both of which are substantially less. 
Fire in the United States 21

The reasons for these differences in distributions between NFPA and NFIRS are not known. It may be that some 

departments reporting summary data to NFPA inadvertently undercount their casualties and losses when reporting on the NFPA survey forms. Another possibility is that there are data entry errors in NFIRS, with larger 

numbers of deaths, injuries and dollar loss per incident record creeping into the database despite edit checks at 

state and federal levels. (It appears that at least some of the dollar-loss difference is due to this.) 

A third possibility for the differences is that with the introduction of abbreviated reporting of small, no-loss 

confined fires in NFIRS, the NFPA sample of these fires is not adequately represented. It is known that, prior to 

abbreviated NFIRS reporting, some departments did not fill out NFIRS forms for minor fires such as food on 

stoves or chimney fires. It is not clear whether these fires were or were not included in the department’s report 

to NFPA and whether this reporting has changed. Also unknown is the actual extent of this problem. 

A fourth possibility is that some jurisdictions use NFIRS as a tracking system for fire casualty information without 

providing the related incident data or vice versa. We know that this possibility does indeed occur from time to 

time in NFIRS. Again, we are unsure of how these incidents and their corresponding losses are reported to NFPA. 

Lastly, it could be that techniques used to generate the NFPA estimates unintentionally favor residential buildings or that NFIRS, because it is a voluntary system and not a true statistical sample, may result in fewer residential losses. 

Resolving the differences between the two major sources of fire statistics in the U.S. is important to prevent 

confusion among users of the data.