10.5 Accidental Automobile Fires

10.5.1 Emissions

Introduction

Category 753 is an area source category that estimates criteria pollutant (particulate, organic, NOx, SOx, and CO) and greenhouse gas emissions (CO2, CH4, and N2O) from accidental automobile fires. The method used to calculate emissions for this category conforms to the method used by the California Air Resources Board (CARB).

Methodology

The total number of automobile accidental fires in California was acquired from the state fire marshal’s office. Automobile fires were apportioned to the Bay Area based on Bay Area population as compared to California’s total population.

The emission factors for automobile fires were derived from the Environmental Protection Agency’s (EPA’s) document AP-42, Section 2.2.2 and 2.4.2. Table 2.2-1 of AP-42 lists the emission factors for uncontrolled auto body incineration, which are based on automobiles that have been partially stripped (tires, seats, etc. removed). Table 2.4-1 lists the emission factors for open burning of automobile upholstery, belts, hoses, and tires in common.

It is assumed that tires are burned in 60% of the automobile fires. Composite emission factors were calculated as a weighted average of the emission factors listed in Table 2.2-1 and 2.4-1 of AP-42, with the assumption that the average car body weighs 3,700 pounds and the components weigh 500 pounds. The criteria pollutant composite emission factors (Lb/Fire) are listed below:

Table 10.14: Composite emission factors (lb/fire).
category PM TOG NOx CO
#753 Accidental Automobile Fires 17 5.41 0.7 21.25

The emission factors for greenhouse gas inventory were developed using above information and emission coefficient data from the Environmental Protection Agency (EPA), the U.S. Department of Energy’s (DOE’s) Energy Information Administration (EIA) and The California Energy Commission (CEC). The Greenhouse gas composite emission factors (Lb/Fire) are as follow:

Table 10.15: Composite emission factors for GHGs (lb/fire).
category CO2 CH4 N2O
#753 Accidental Automobile Fires 626.8 2 0.135

Temporal Variation

The monthly activity and the weekly activity are uniform. The daily activity occurs primarily during daylight hours.

County Distribution

Automobile fires were apportioned to the Bay Area counties based on population by county. This was used directly in the county distribution except for Solano and Sonoma which were adjusted to include only areas inside the District using household population.

Table 10.16: County fractions.
category ALA CC MAR NAP SF SM SNC SOL SON
#753 Accidental Automobile Fires 21.1% 15.0% 3.5% 1.9% 10.9% 9.9% 24.9% 6.0% 6.8%