2.7 Deaths, non-fatal injuries, and post-traumatic stress disorder

Caton et al. (2017) discuss experimental and fire-experience evidence quantifying fundamental exposure conditions contributing to ignition and fire spread, especially firebrand production, dimensions, mass, temperature, and fuel bed ignition. They also provide various historical fire statistics for the United States.

Hakes et al. (2017) complement Caton et al.’s review by quantifying the response of various building components and systems such as roofing, gutters, eaves, vents, siding, windows, glazing, decks, porches, patios, fences, mulches, and debris. The data may ultimately contribute to a future physicsbased model of fire transmission, damage, and property loss.

Manzello (2014) describes an experimental program by the US National Institute of Standards and Technology to understand structure vulnerabilities to wind-driven firebrand showers in wildlandurban interface fires. It does not offer quantitative relationships between attributes of the WUI fire and ignition probability or degree of damage.

2.7 Deaths, non-fatal injuries, and post-traumatic stress disorder

Ahrens and Evarts (2020) summarize fire death statistics in the United States in 2019. Their Table 1 shows that the US experienced 264,500 fires in one- and two-family homes, including manufactured homes, resulting in 2,390 civilian deaths and 8,800 non-fatal civil injuries, meaning 0.0090 deaths per house fire and 0.0333 non-fatal injuries per house fire.

CAL FIRE data suggest lower fatality rates in WUI fires. In California’s 20 most destructive wildfires, 207 people died and 51,745 structures were destroyed, suggesting a fatality rate of 0.0040 deaths per destroyed structure. Since destroyed structures represent about 93% of building ignitions, the fatality rate equates with about 0.0037 deaths per ignition. If non-fatal injuries occur in proportion to deaths, these data suggest 0.0138 non-fatal injuries per ignition.

There is some uncertainty about fatality numbers, however. Von Kaenel (2020) suggests that the Camp Fire killed about 140 people, rather than the official tally of 85 (CAL FIRE 2019), and the number may be even higher. Survivors claim that many people died after the fire because of respiratory conditions, stress, and other problems that are hard to directly causally connect to the fire. Prime Clerk (2020) provides a database of claims against Pacific Gas and Electric Company (PG&E) resulting from the Camp Fire (among others). It includes approximately 270 unique names of people in wrongful death claims. Using 140 to 270 deaths as the likely range of actual deaths and 14,343 housing units damaged or destroyed, the fatality rate appears to range between 0.0098 and 0.019 deaths per ignition, or approximately one to two times the nationwide average from all structure fires suggested by Ahrens and Evarts (2020).

Prime Clerk’s (2020) database lists approximately 28,475 personal injury claims against PG&E resulting from the Camp Fire, judging each unique address associated with a personal injury claim from the Camp Fire as one injury. Approximately 52,000 people were evacuated because of the Camp Fire, so 28,000 injuries seem implausible, especially since most of the claimant addresses are in Butte County, as opposed to people in distant downwind counties who might have suffered respiratory problems because of smoke. Still, even if only 10% of injury claims were legitimate, the implication is that WUI fire injuries outnumber deaths by 10 to 1, as opposed to 3 to 1 as suggested by Ahrens and Evarts (2020).