Every year, wildfires burn across the U.S., and a growing number of people are living where wildfires are a real risk. According to the National Fire Protection Association (NFPA), in 2018, more than 58,000 fires burned nearly nine million acres across the U.S. More than 25,000 structures were destroyed, including 18,137 residences and 229 commercial structures.
In recent years, wildfires have only increased in destructive power. For instance, in 2020, five of the six largest fires on record burned in California and Oregon, resulting in historic levels of wildfire spread and damage. Wildfires across the West led to weeks-long periods of unhealthy air quality levels for millions of people. Just last year, a fire in Boulder, Colorado devastated that community.
Climate change has been a key factor in increasing the risk and extent of wildfires in the western U.S. Wildfire risk depends on a number of factors, including temperature, soil moisture, and the presence of trees, shrubs, and other potential fuel. All of these components have strong direct or indirect ties to climate variability and climate change. Climate change enhances the drying of organic matter in forests (the material that burns and spreads wildfires), leading to a doubling of large fires between 1984 and 2015 in the western U.S., according to the Center for Climate and Energy Solutions.
Additional research from the same organization shows recent changes in climate have created warmer, drier conditions. Increased drought and longer fire seasons are elevating wildfire risk. For much of the western U.S., projections show that an average annual one-degree Celsius temperature increase would raise the median burned area per year by as much as 600% in some types of forests. In the southeastern U.S., modeling suggests increased fire risk and longer fire seasons going forward, with at least a 30% increase expected from 2011 in the area burned by lightning-ignited wildfires by 2060.
Building Materials and Techniques
As buildings became larger, building techniques and materials have changed. Lightweight construction has become commonplace. Natural fibers have been replaced with synthetics. These changes have caused fires to burn faster, hotter, and dirtier, resulting in more total losses and potential for injury.
There are a few old adages in the fire service that most of us learned going through fire school: “Put the wet stuff on the red stuff,” and, “The fire service: 200 years of tradition, unimpeded by progress.” Happily, the second is becoming less accurate.
Smoke and fire alarms, carbon monoxide detectors, commercial and residential sprinkler systems, and advances in firefighting apparatus, training, and techniques have largely offset the increase in danger caused by the “modern” approach to buildings. In 2010, there were 3,445 fire deaths (population 309,327,143.) That number remained surprisingly constant despite the increasing population: According to the U.S. Fire Administration, the fire death rate per million population was 11.1 in 2010 and 10.7 in 2019.
Fire Investigations
Virtually all fires need to be investigated. How a fire is classified—whether accidental, natural, incendiary, or undetermined—will determine whether someone can be found criminally or civilly responsible. And, in this arena, advancements in investigative techniques have flourished.
The “bible” of the fire investigative world—NFPA 921 “Guide for Fire and Explosion Investigations”—has been newly revised. The 2021 edition contains some significant edits and updates related to fire patterns, arc mapping, and fire classification.
The chapter on “Fire Effects and Fire Patterns” was completely rewritten. The concept of fire effects was elevated and defined as “observable or measurable changes” to materials. Arc mapping is now categorized as a fire pattern, and there has been a number of changes to the text to reflect that update. There have also been additions to the text on the probabilistic nature of arcing, added emphasis on the importance of a complete arc map, and renewed cautions that arc sites are not necessarily located at the area of origin. Fire classifications that we knew and loved have been removed.
The point of all of this is to focus investigators and make their origin and cause determinations more scientific. Happily for us, there have been significant advances in the technology of fire investigation.
The Increasing Role of Technology
For a number of years, there have been laboratory-based gas chromatography systems. Of late, field portable Gas Chromatography/Mass Spectrometry (GC/MS) systems have been under evaluation. The National Institute for Science and Technology (NIST) has engaged in a multi-year effort to evaluate these systems. The process for collecting fire scene samples aligned with industry standards to include canine alerts, Photoionization Detector (PID) confirmation, evidence collection in fire debris containers, and GC/MS sampling of the area of interest. The findings offer insights into the future of obtaining lab quality GC/MS data from the fire scene.
3D laser scanners have also been appearing more frequently at fire scenes as the cost of the scanning has come down significantly. Back in 2014, over 5,500 acres near Portland, Oregon burned. This was called the 36 Pit Fire. The firefighters used a FARO 3D laser scanner at the scene. The 3D scanner was able to operate in this environment despite the active fire conditions. Before 3D laser scanners, investigators at crime scenes like the 36 Pit Fire origin site could only capture what they thought was important at the time. Whether they used hand measurements or a total station—which required markers to be placed—they could only collect the data they specifically intended to collect.
But as the investigation progressed, they would often find there were other important details they didn’t record. And, days later, it was impossible to get that information from the scene.
The sheer amount of data the 3D laser scanner can collect simply dwarfs more traditional methods, and it was a critical tool in determining the origin of the 36 Pit Fire. According to reports, without 3D laser scanners, fire and criminal investigators would have had to collect around 150 data points over the course of a couple of days on the scene (an area about 200 ft. by 300 ft.) using multiple methods. However, using the 3D laser scanner, investigators were able to capture 12 million point clouds in under an hour. The result of this detailed evaluation of the data exonerated a suspect and established the fire was accidental in nature.
I have used this technology in a multiple-death house fire and a mine explosion case. The scans can be overlaid with photos of the house from the most recent sales listing. This gave us a clear view of the house, the escape routes, and the fire propagation.
There are available thermal scanners designed for detecting hotspots. These can detect hotspots inside structures, walls, ceilings, and floors. There are accelerant detectors, often used in arson investigations but certainly helpful in defending civil suits. Some of these can detect accelerants down to one ppm (part per million). There are gas detectors with ultraviolet LEDs that cause certain accelerants to glow and fluoresce.
Software has been developed to allow investigators to manage, maintain, and track property and evidence from the fire scene to the courthouse, including things as simple as “QR” codes and barcodes.
Even technology we take for granted has greatly improved fire investigation. Once people began using email and websites to communicate, organizations learned that they could hold online conferences where experts can present and share papers, strategies, and theories.
The conference presenters and participants can be anywhere in the world. One recent online conference on natural hazard reduction had 450 participants, largely because it was conducted as a listserv on which comments and papers were delivered directly to those who signed up.
Even casual use of the internet and email can yield incredible amounts of information designed specifically for fire investigators. Just visit the International Association of Arson Investigators homepage and you will see a wealth of information. There is even a a page called ChemFinder that will bring up material safety data sheets that contain information on any chemical name you key in, telling you how to store it and how to fight fires started by that chemical.
Ongoing testing from entities like NIST, UL, and NFPA have examined and debunked many misconceptions about fire behavior. Other perceptions have been examined and proven. The industry as a whole understands the need to bring science to fire investigation, and, luckily for all of us, that is exactly what has been happening.