11.1 Sector Description and Overview

Structure fires and motor vehicle fires are sources of both gaseous and pollutants [ref 1, ref 2, ref 3]. In previous NEI cycles, only a handful of States/Locals/Tribal (SLT) agencies have submitted estimates for these sources. EPA has removed (“tagged out”) these sources in previous NEIs because of how limited these submittals have been and the overall insignificance of their emissions relative to other sources.

Structure fires result from unintentional actions, arson, or natural events. Most motor vehicle fires are the result of unintentional actions or arson. Structure fires include those from residential, commercial, and industrial sites where a fire incident is reported [ref 4]. Fires that are contained with the structure, such as a trash fire or incinerator or commercial compactor fire with no flame damage to structure, are not included. Similarly, motor vehicle fires include those to all onroad mobile and offroad vehicles including recreational vehicles, campers, trailers, bulldozers, farm equipment, dirt bikes, and heavy equipment, but does not include rail vehicles, water vehicles, and aircraft fires.

For the 2023 NEI, we crafted a national set of emission estimates for both motor vehicle fires and structure fires based on commonly available dataset, with assumptions refined from those available in previous methodology documents [ref 2, ref 3]. All estimates for motor vehicle fires and structure fires are provided in a single, separate SCC for each type.

Here, an introduction to the new methods utilized to estimate motor vehicle fires and structure fires emissions are outlined. While the emissions impact from this addition are minimal at the national and even State level, adding structure fires and motor vehicle fires as an EPA method serves to make the NEI more complete, one of the basic tenets we have with every NEI. Table 11.1 lists the SCCs for these sources. The SCC level 1 and 2 descriptions are “Miscellaneous Area Sources; Other Combustion” for both SCCs. The EIS Sector for both SCCs is “Miscellaneous Non-Industrial NEC”.

Table 11.1: Structure Fires and Motor Vehicle Fires Source Classification Codes

SCC	SCC L3 Description	SCC L4 Description
2810030000	Structure Fires	Unspecified
2810050000	Motor Vehicle Fires	Unspecified