### 7.14-1 

## SECTION 7.14
STRUCTURE AND AUTOMOBILE FIRES (Updated March 1999)



### METHODS AND SOURCES These categories are used to inventory t he combustion emissions from structure, mobile home, and automobile fires. The Structure firescategory includes residential and commercial structures as well as mob ile home fires. The criteria pollutant emissions for 1996 are presented in Table II ( Structure Fires ) and Table III ( Automobile Fires ). Estimates of building, mobile home, and automobile fires in 1996 were based on data from an annual report generated by the California Fire Incident Reporting System (CFIRS). 1


### STRUCTURE FIRES For structure fires, the average amount of stru cture and content material burned are first estimated. An average percent structural lo ss per fire was calculated by dividing the total monetary damage due to fires by the product of the average value of a residence in California and the number of structure fires. 2 

### The average loss per fire is estimated to be 7.3 percent. This estimate can be applied to structure loss and content loss. Based on census data, the average size of ex isting homes in California is estimated to be 1,649 square feet. 3 

### The average residence has approximately 11,000 board feet of lumber in the structure, according to info rmation provided by the National Association of Home Builders. 4 

### ARB staff assumed an average of one ton of material per 1,000 board feet. Therefore, an average residence has approximately 11 tons of combustible material. Assuming a rate loss of 7.3 percent, the structure lo ss is estimated to be 0.80 tons per fire.

EMISSION INVENTORY SOURCE CATEGORY Miscellaneous Processes/Fires EMISSION INVENTORY CODES (CES CODES) AND DESCRIPTION 660-656-0200-0000 (47324) Structure Fires 660-658-0200-0000 (57307) Automobile Fires

### 7.14-2 Next, the amount of content material burned is estimated. The National Bureau of Standards lists the combustible contents per s quare foot of the functional areas of the average home. 5

### These figures are then multiplied bythe percent of fires estimated to originate within each of these functional areas, 1 

### and the products are then added to obtain the weighted average of 7.91 pounds per square foot. Origin of Combustibles Weighted Average Functional Area fires(%) (lbs/sq. ft.) (lbs/sq. ft.) Bedroom 28.96 10.4 3.012 Sleeping Area 0.20 10.4 0.021 Dining Area 2.20 7.2 0.159 Kitchen 53.92 6.8 3.667 Bathroom 6.32 7.0 0.443 Laundry 8.08 7.2 0.582 Office 0.17 7.9 0.013 Other 0.13 9.6 0.012 7.909 With a 7.3 percent loss rate, an average of 7.91 pounds of combustible contents per square foot, and assuming an average floor s pace of 1649 square feet, the content loss for the average residential fire would be: [(1649) x (0.073) x (7.91)] / 2000 = 0.48 tons/fire Total amount burned per residential fire (fuel loading) = structure loss + content loss = 0.80 + 0.48 = 1.28 tons/fire Structure fire emission factors in pounds per ton of material burned for TOG, CO and PM have been obtained from tests on t he burning of model wood buildings. 6 

### The emission factor for NOx is assumed to be si milar to that listed in AP-42 for municipal refuse. 7 

### These emission factors have been converted to units of pounds per fire using the factor of 1.28 tons/fire.

Emission Factors for Structural Fires TOG CO NOx SOx PM Pounds/Ton 13.9 168.0 4.0 0 10.8 Pounds/Fire 17.8 215.0 5.1 0 13.8 CFIRS structure fires data is available on t he county level. For those instances where an air basin splits a county, emissions estimates are apportioned based on total housing

### 7.14-3 units as estimated by the California Department of Finance (DOF). AUTOMOBILE FIRES The emission factors for automobile fires are taken from AP-42, Sections 2.2.2 and 2.4.2. Table 2.2-1 of AP-42 lists the emission factors for uncontrolled auto body incineration. These are based on automobile s that have been partially stripped (tires, seats, etc. removed). Table 2.4-1 of AP- 42 lists the emission factors for open burning of automobile components. These emission fact ors are for upholstery, belts, hoses, and tires burned in common.
It has been assumed that tires are burned in 60 percent of the automobile fires. Composite emission factors have been calc ulated as a weighted average of the emission factors listed in Table 2.2-1 and 2. 4-1 of AP-42. It has been assumed that the average car body weighs 3,700 pounds and the components weigh 500 pounds. The composite emission factors are listed below. Their derivation is presented in Table I. Emission Factors for Automobile Fires (lbs/fire) TOG CO NOx SOx PM 7.21 21.25 0.7 0 17 For automobile fires, sub-county split s between air basins are based on population estimates from DOF.
ASSUMPTIONS 1. The emission factors that have been derived for structure fires are also valid for mobile home fires. 2. An average residence is constructed wit h approximately 11 tons of combustible material. 3. An average residence covers an area of 1,649 square fee. 4. The tires are burned in 60 percent of the automobile fires. 5. The average car body weighs 3,700 pounds. 6. The components on an average car weigh 500 pounds. 7. The estimates of structural loss rate (7 .3%) and content loss rate (7.91 lb/sq. ft.) continue to be applicable.

### 7.14-4 COMMENTS AND RECOMMENDATIONS Emission factors for mobile home and commerc ial structure fires may be significantly different from those for residential fires. Li ttle data are available; therefore, the emission factors for mobile home fires and commercial structure fires are assumed to be the same as for residential structure fires. The emission factors for oxides of nitrogen, which are actually for open burning of municipal refuse, may not be the best estimate for structure fires. A more accurate estimate of the percentage of cars that burn completely (tires included) needs to be determined, since most em issions are associated with automobile component and tire combustion.

CHANGES IN METHODOLOGY The estimate of the average size of a residence in California has been increased based on census data. This increase resulted in a larger estimate of the amount of material burned per fire (fuel loading). As a resul t, emission factors in pounds of pollutant per fire have also been increased. Emission estimates have been adjusted to acc ount for the newly formed Salton Sea Air Basin.

DIFFERENCES BETWEEN 1995 AND 1996 EMISSION ESTIMATES The differences between the 1995 and 1996 emission estimates for structure fires and automobile fires are primarily due to the di fference in the numbers of fire incidents. Increases in emission factors have also affected emission estimates.

TEMPORAL ACTIVITY For both categories, the annual activity and the weekly activity are uniform. The daily activity occurs primarily during daylight hours.

### 7.14-5 SAMPLE CALCULATIONS To calculate the emissions from Structural Fires(CES 47324), and Automobile Fires (CES 57307) for Sacramento County in the Sacramento Valley air basin: Number of Structural Fires= 1,546 Number of Automobile Fires = 1,877 Emissions = [Process Rate (# of Fi res)] x (Emission Factor) / 2000 lbs/ton

The process rate and emissions for Sacramento County are summarized below: Process Rate Emissions (tons/yr) Type of Fires (# of Fires) TOG CO NOx SOx PM Structural Fires 1,546 13.7 166.2 3.94 0 10.7 Automobile Fires 1,877 6.8 19.9 0.66 0 16.0

### 7.14-6 REFERENCES 1. California State Fire Marshall, Calif ornia Fire Incident Reporting System, 1996. 2. California State Fire Marshall, Calif ornia Fire Incident Reporting System, 1991. 3. Sue Lord, American Housing Survey Branch, Census Bureau, 1999. 4. National Association of Hous e Builders, http://www.nahb.com/mub.html. 5. National Bureau of Standards, Com bustible Contents in Buildings. 6. Butler, C.P. and Darley, E.E. “Fires Dy namics of Model Wood Buildings,” Fire and Flammability, Vol. 3, p. 336 (October 1972). 7. U.S. Environmental Protection Agency, Compilation of Air Pollutant Emission Factors, AP-42, Section 2.2 and 2.4. (April 1973).

UPDATED BY Carolyn Lozo March 1999

### 7.14-7 Table I Derivation of Emission Factors for Automobile Fires The emission factors for uncontrolled auto body incineration (Table 2.6-1 of AP-42, 1/95) are: Emission Factors for Auto Body (lbs/car) TOG CO NOx SOx PM 0.91 2.5 0.1 0 2.0

The emission factors for automobile components (Table 2.5-1 of AP-42), including upholstery, belts, hoses and tires, are listed in terms of lbs/ton of components burned and must be multiplied by the weight of components per car. If the components per car are assumed to be 500 lbs, the emission factors for components in terms of lbs/car can be converted as show below. Weight of components = 500 lbs/car = 0.25 tons/car PM emission factor = (100 lbs/ton components) x (0.25 tons components/car) = 25 lbs/car

Emission Factors for Components (lbs/car) TOG CO NOx SOx PM 10.5 31.25 1.0 0 25

Composite emission factors, assuming that tires are burned in 60% of automobile fires, were calculated as follows: Composite EF = [EF (body) + EF (components)] x 0.6 + [EF (body)] x 0.4 The weighted composite emission factors are listed below: Composite Emission Factors (lbs/fire) TOG CO NOx SOx PM 7.21 21.25 0.7 0 17.0

### 7.14-8 Table II 1996 Area Source Emissions Activity: Unspecified Activities Process: Structure Fires Entrainment: Solid Material Combustion Dimn: CES: 47324 Process Rate Unit: Fires AB County Process Rate TOG Emis. (Tons / Year) CO Emis. (Tons / Year) NOX Emis. (Tons / Year) SOX Emis. (Tons / Year) PM Emis. (Tons / Year) GBV ALPINE 1 0.01 0.16 0.00 0.00 0.01 INYO 2 0.03 0.33 0.01 0.00 0.02 MONO 0 0.00 0.00 0.00 0.00 0.00 LC LAKE 44 0.60 7.21 0.17 0.00 0.46 LT EL DORADO 17 0.23 2.78 0.07 0.00 0.18 PLACER 2 0.03 0.33 0.01 0.00 0.02 MC AMADOR 9 0.12 1.47 0.04 0.00 0.09 CALAVERAS 30 0.41 4.91 0.12 0.00 0.32 EL DORADO 62 0.84 10.16 0.24 0.00 0.65 MARIPOSA 52 0.70 8.52 0.20 0.00 0.55 NEVADA 50 0.68 8.19 0.20 0.00 0.53 PLACER 8 0.11 1.31 0.03 0.00 0.08 PLUMAS 3 0.04 0.49 0.01 0.00 0.03 SIERRA 0 0.00 0.00 0.00 0.00 0.00 TUOLUMNE 90 1.22 14.74 0.35 0.00 0.95 MOJ KERN 92 1.25 15.07 0.36 0.00 0.97 LOS ANGELES 169 2.29 27.68 0.66 0.00 1.78 RIVERSIDE 17 0.23 2.78 0.07 0.00 0.18 SAN BERNARDINO 355 4.81 58.15 1.38 0.00 3.75 NC DEL NORTE 29 0.39 4.75 0.11 0.00 0.31 HUMBOLDT 58 0.79 9.50 0.23 0.00 0.61 MENDOCINO 74 1.00 12.12 0.29 0.00 0.78 SONOMA 173 2.34 28.34 0.67 0.00 1.83 TRINITY 1 0.01 0.16 0.00 0.00 0.01 NCC MONTEREY 197 2.67 32.27 0.77 0.00 2.08 SAN BENITO 25 0.34 4.10 0.10 0.00 0.26 SANTA CRUZ 162 2.20 26.54 0.63 0.00 1.71 NEP LASSEN 13 0.18 2.13 0.05 0.00 0.14 MODOC 2 0.03 0.33 0.01 0.00 0.02 SISKIYOU 8 0.11 1.31 0.03 0.00 0.08 SC LOS ANGELES 5119 69.36 838.49 19.96 0.00 54.01 ORANGE 1470 19.92 240.79 5.73 0.00 15.51 RIVERSIDE 755 10.23 123.67 2.94 0.00 7.97 SAN BERNARDINO 1169 15.84 191.48 4.56 0.00 12.33 SCC SAN LUIS OBISPO 143 1.94 23.42 0.56 0.00 1.51 SANTA BARBARA 152 2.06 24.90 0.59 0.00 1.60 VENTURA 7 0.09 1.15 0.03 0.00 0.07 SD SAN DIEGO 1813 24.57 296.97 7.07 0.00 19.13 SF ALAMEDA 236 3.20 38.66 0.92 0.00 2.49 CONTRA COSTA 961 13.02 157.41 3.75 0.00 10.14 MARIN 201 2.72 32.92 0.78 0.00 2.12 NAPA 205 2.78 33.58 0.80 0.00 2.16 SAN FRANCISCO 408 5.53 66.83 1.59 0.00 4.30 SAN MATEO 346 4.69 56.67 1.35 0.00 3.65 SANTA CLARA 661 8.96 108.27 2.58 0.00 6.97 SOLANO 3 0.04 0.49 0.01 0.00 0.03 SONOMA 152 2.06 24.90 0.59 0.00 1.60 SJV FRESNO 1310 17.75 214.58 5.11 0.00 13.82 KERN 400 5.42 65.52 1.56 0.00 4.22 KINGS 146 1.98 23.91 0.57 0.00 1.54 MADERA 143 1.94 23.42 0.56 0.00 1.51 MERCED 209 2.83 34.23 0.82 0.00 2.20 SAN JOAQUIN 192 2.60 31.45 0.75 0.00 2.03 STANISLAUS 482 6.53 78.95 1.88 0.00 5.09 TULARE 592 8.02 96.97 2.31 0.00 6.25 SS IMPERAIL 82 1.11 13.43 0.32 0.00 0.87 RIVERSIDE 187 2.53 30.63 0.73 0.00 1.97 SV BUTTE 356 4.82 58.31 1.39 0.00 3.76 COLUSA 1 0.01 0.16 0.00 0.00 0.01 GLENN 4 0.05 0.66 0.02 0.00 0.04 PLACER 39 0.53 6.39 0.15 0.00 0.41 SACRAMENTO 1184 16.04 193.94 4.62 0.00 12.49 SHASTA 293 3.97 47.99 1.14 0.00 3.09 SOLANO 2 0.03 0.33 0.01 0.00 0.02 SUTTER 43 0.58 7.04 0.17 0.00 0.45 TEHAMA 102 1.38 16.71 0.40 0.00 1.08 YOLO 124 1.68 20.31 0.48 0.00 1.31 YUBA 29 0.39 4.75 0.11 0.00 0.31 TOTAL 21466 290.86 3516.11 83.72 0.00 226.46

Fraction of Reactive Organic Gases (FROG): .7500 (Reactive Organic Gases (ROG) Emissions = TOG X FROG) Fraction of PM10 (FRPM10): .9800 (PM10 Emissions = PM X FRPM10)

### 7.14-9 Table III 1996 Area Source Emissions Activity: Unspecified Activities Process: Unplanned Fires Entrainment: Solid Material Combustion Dimn: Auto Body CES: 57307 Process Rate Unit: Autos Burned AB County Process Rate TOG Emis. (Tons / Year) CO Emis. (Tons / Year) NOX Emis. (Tons / Year) SOX Emis. (Tons / Year) PM Emis. (Tons / Year) GBV ALPINE 0 0.00 0.00 0.00 0.00 0.00 INYO 7 0.03 0.07 0.00 0.00 0.06 MONO 1 0.00 0.01 0.00 0.00 0.01 LC LAKE 38 0.14 0.40 0.01 0.00 0.32 LT EL DORADO 8 0.03 0.09 0.00 0.00 0.07 PLACER 3 0.01 0.03 0.00 0.00 0.03 MC AMADOR 20 0.07 0.21 0.01 0.00 0.17 CALAVERAS 37 0.13 0.39 0.01 0.00 0.31 EL DORADO 30 0.11 0.32 0.01 0.00 0.26 MARIPOSA 24 0.09 0.26 0.01 0.00 0.20 NEVADA 36 0.13 0.38 0.01 0.00 0.31 PLACER 13 0.05 0.14 0.00 0.00 0.11 PLUMAS 1 0.00 0.01 0.00 0.00 0.01 SIERRA 0 0.00 0.00 0.00 0.00 0.00 TUOLUMNE 87 0.31 0.92 0.03 0.00 0.74 MOJ KERN 83 0.30 0.88 0.03 0.00 0.71 LOS ANGELES 259 0.93 2.75 0.09 0.00 2.20 RIVERSIDE 22 0.08 0.23 0.01 0.00 0.19 SAN BERNARDINO 405 1.46 4.30 0.14 0.00 3.44 NC DEL NORTE 8 0.03 0.09 0.00 0.00 0.07 HUMBOLDT 38 0.14 0.40 0.01 0.00 0.32 MENDOCINO 44 0.16 0.47 0.02 0.00 0.37 SONOMA 13 0.05 0.14 0.00 0.00 0.11 TRINITY 3 0.01 0.03 0.00 0.00 0.03 NCC MONTEREY 181 0.65 1.92 0.06 0.00 1.54 SAN BENITO 28 0.10 0.30 0.01 0.00 0.24 SANTA CRUZ 132 0.48 1.40 0.05 0.00 1.12 NEP LASSEN 6 0.02 0.06 0.00 0.00 0.05 MODOC 1 0.00 0.01 0.00 0.00 0.01 SISKIYOU 17 0.06 0.18 0.01 0.00 0.14 SC LOS ANGELES 7826 28.21 83.15 2.74 0.00 66.52 ORANGE 1645 5.93 17.48 0.58 0.00 13.98 RIVERSIDE 963 3.47 10.23 0.34 0.00 8.19 SAN BERNARDINO 1335 4.81 14.18 0.47 0.00 11.35 SCC SAN LUIS OBISPO 142 0.51 1.51 0.05 0.00 1.21 SANTA BARBARA 104 0.37 1.11 0.04 0.00 0.88 VENTURA 5 0.02 0.05 0.00 0.00 0.04 SD SAN DIEGO 2189 7.89 23.26 0.77 0.00 18.61 SF ALAMEDA 292 1.05 3.10 0.10 0.00 2.48 CONTRA COSTA 872 3.14 9.27 0.31 0.00 7.41 MARIN 112 0.40 1.19 0.04 0.00 0.95 NAPA 153 0.55 1.63 0.05 0.00 1.30 SAN FRANCISCO 196 0.71 2.08 0.07 0.00 1.67 SAN MATEO 245 0.88 2.60 0.09 0.00 2.08 SANTA CLARA 837 3.02 8.89 0.29 0.00 7.11 SOLANO 6 0.02 0.06 0.00 0.00 0.05 SONOMA 93 0.34 0.99 0.03 0.00 0.79 SJV FRESNO 1485 5.35 15.78 0.52 0.00 12.62 KERN 359 1.29 3.81 0.13 0.00 3.05 KINGS 157 0.57 1.67 0.05 0.00 1.33 MADERA 210 0.76 2.23 0.07 0.00 1.79 MERCED 281 1.01 2.99 0.10 0.00 2.39 SAN JOAQUIN 117 0.42 1.24 0.04 0.00 0.99 STANISLAUS 388 1.40 4.12 0.14 0.00 3.30 TULARE 690 2.49 7.33 0.24 0.00 5.87 SS IMPERIAL 63 0.23 0.67 0.02 0.00 0.54 RIVERSIDE 238 0.86 2.53 0.08 0.00 2.02 SV BUTTE 256 0.92 2.72 0.09 0.00 2.18 COLUSA 1 0.00 0.01 0.00 0.00 0.01 GLENN 7 0.03 0.07 0.00 0.00 0.06 PLACER 66 0.24 0.70 0.02 0.00 0.56 SACRAMENTO 1148 4.14 12.20 0.40 0.00 9.76 SHASTA 226 0.81 2.40 0.08 0.00 1.92 SOLANO 3 0.01 0.03 0.00 0.00 0.03 SUTTER 32 0.12 0.34 0.01 0.00 0.27 TEHAMA 106 0.38 1.13 0.04 0.00 0.90 YOLO 129 0.47 1.37 0.05 0.00 1.10 YUBA 24 0.09 0.26 0.01 0.00 0.20 TOTAL 24546 88.48 260.77 8.58 0.00 208.65

Fraction of Reactive Organic Gases (FROG): 0.7500 (Reactive Organic Gases (ROG) Emissions = TOG X FROG) Fraction of PM10 (FRPM10): 0.9970 (PM10 Emissions = PM X FRPM10)