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Arson Science Rewritten
An anonymous reader handed us a link to an AP story about advances in the science of arson investigation. Many assumptions about fire, long held by investigators, have been overturned in recent years as scientists have come to understand concepts like 'flashover'. The repercussions of these findings is having an effect not unlike the use of DNA in crime-solving; people are being set free, and old cases are being re-examined. From the article: "Significantly, flashover can create very hot and very fast-moving fires. And it can occur within just a few minutes, dashing the concept that only arson fires fueled by accelerants can quickly rage out of control. The studies began to chip away at the old beliefs -- critics call them myths -- but it took years. Through the 1980s, texts at the National Fire Academy in Emmitsburg, Md., still taught the traditional techniques. It wasn't until 1992, when a guide to fire investigations by the National Fire Protection Association -- 'NFPA921: Guide for Fire and Explosion Investigations' -- clearly laid out, in a document relied upon by authorities nationwide, that the earlier beliefs were wrong."
you would be skeptical about the need for "accelerants". If you've ever seen a fire move through a room, it can go from a small area to engulfing the entire thing in less than a minute without any help from gasoline etc. I'm pretty sure that what happens is that the heat from the small fire vaporizes ordinary non-volatile things, like household furnishings or materials, and those vapors then act as the accelerant.
I know there was a case a few years ago where an "arsonist" in TX was executed for having killed his family, and within less than a year it was established that he was innocent.
I'll just say, the idea of someone being executed based on expert testimony from arson investigators, who are not even scientists, is appalling. Experts are only right until some new piece of knowledge comes along and changes the field.
And Jay Leno made jokes about me getting set on fire in prison. And all the inmates were so aglow with inner certainty as I was gang raped to death. Gosh, I guess no harm, no foul.
-signed, dead guy who was obviously guilty
I used to be a volunteer firefighter and also served as a fire investigator. My experience began around 1981 or so; later (late 90s), I worked for a Police Department doing crime scene work and part of that was fire investigation.
From TFA:
Up until the 1990s, this is what fire investigators were taught:
Fires always burn up, not down.
I was NEVER taught that; just the opposite. Fires tend to burn up FASTER than they burn down, but geez, anyone who has ever actually WATCHED a fire burn knows this statement is nonsense.
Fires that burn very fast are fueled by accelerants; "normal" fires burn slowly.
I was NEVER taught that; just the opposite. We were taught that accelerates were ONE WAY a fire MIGHT burn faster than you would expect under similar conditions. We were also taught that is EXTREMELY difficult to gauge how fast a fire "should have" burned. I did my first chemical test on fire debris in 1986 using GC/MS via a very simple headspace analysis on a sample that the state lab sent back as negative (my test was positive for something, perhaps ambient artifacts, but was an educational run, not an 'official' test). With the negative test result, we sure did not try to use evidence of 'how fast that fired burned' to assert the presence of an accelerant.
Arsons fueled by accelerants burn hotter than "normal" fires.
Somebody is oversimplifying the concept of "fire load" here. There are a WHOLE LOT of things than can make a fire burn hotter than 'normal.' In fact, as a common theme I am trying to represent, "normal" is not a well defined term for real-world fires. Rural firefighters and investigators certainly knew this before 1992.
In fact, this statement glosses over another issue about arson - they often, quite often, don't involve 'accelerants' at all.
The clues to arson are clear. Burn holes on the floor indicate multiple points of origin. Finely cracked glass (called "crazed glass") proves a hotter-than-normal fire. So does the collapse of the springs in bedding or furniture, and the appearance of large blisters on charred wood, known as "alligatoring."
The clues to arson are clear?? Man, I clearly remember in the early 1980's being taught exactly the OPPOSITE of what this article says was the "norm" back then. Perhaps it was taught somewhere, but not in RURAL North Carolina. Absolutely NONE of these "clues" are evidence of arson - only of certain fire conditions.
What we were taught in our arson investigation classes, and what I came to learn through experience, is that arson was/is and EXTREMELY difficult crime to prove. That means it is difficult to prove that a fire was arson, much less who did it.
Truthfully, based on my experience, I don't see the point of this article. It asserts 'beliefs' about fire investigation pre-1992 that just are not true.
And finally, the article gives the tragic story of the Lee family that occured in 1989. While presenting NONE of the evidence that was used to convict him, the story creates the straw man that just because it was 1989 and fire investigation changed (around then, according to the article), he must be framed. I don't know of his guilt or innocence, but that's a might big leap of logic.
Computational Chemistry products and services.
Sad thing is, mansonry conducts heat. While some regions might not consider this a problem, try living in a brick house when the temperature drops below 0 farenheight. It can't be fun, so the solution is to build a brick exterior and set up a wooden insulated studwall on the interior.
Besides, what is going to hold up your concrete second floor? Or is it that all houses in your country have no cellars or second floors? The cost of constructing a house made entirely of mortar, brick, and stone is immense. Thus, wooden houses.
In the ideal world, nothing burns. In the real world, even concrete and steel give under fire.
In the ideal world, concrete and metal buildings are as inexpensive as wood. In the real world, this just isn't so.
In Mother Russia, the concrete burns you!
-jbevren
that this thread will turn into a flame war.
My script don't crash! She crashes, you crashed her!
Tried reading the article but my Sony laptop caught on fire.
Pretty much all (Western and Eastern) European home construction is concrete / brick based and this extends through most of Russia and large parts of the rest of the world. Building out of wood is a foreign concept for a large number of people in the world. Many countries don't exactly have huge forests either - nothing like what we enjoy in North America.
;)
Basically Europe is completely deforested. There are forests, sure, but they would be gone pretty quickly if people started building homes out of wood.
As for the engineering aspects - concrete is strong and you can easily drop a concrete slab as the floor on your second story if you use walls of reasonable thickness - or you can use wood flooring suspended on a central beam(s) or one of dozens of other ways that builders use to suspend a floor in a wood house. Very few houses in Europe are only 1 story.
I've seen pre-fabed buildings being put together (and quickly) in Poland and Eastern Europe using both methods - a crane, a few hours and a welder is all it takes to get the structure done since the buildings come on the truck with rebar in place, holes and supports already in the concrete. Pretty cool actually.
Assembling a house out of brick isn't terribly difficult either - many people in Eastern Europe build their own houses, by hand, slowly, after they come back from their day jobs or whatever. Try doing that with wood construction and you'll end up with a crooked house that falls down in a year.
There is also a newer technology under the category of "insulated concrete forms" (ICF) - basically big hollow styrofoam blocks that you assemble like legos and fill with concrete (they have internal structure and rebar holding them together)
A house built with ICF has superior insulating properties (and does a fair job of blocking wifi signals too
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After something like 40 years of this being accepted, someone actually tested it. Result: no freaking correlation at all. The variation in composition of bullets within a given box was the same as variation among bullets from different boxes, purchased years apart. This is a completely worthless forensic technique.
Or consider early DNA testing. Up until at least the mid '90s (I don't know what they do now) a DNA test only looked for matches at a small number of base pairs. For any given DNA sample tested, there would be thousands of people in the world that matches that sample. What this meant was the the scientifically correct way to use DNA testing was to find your suspects using traditional police techniques, and THEN use a DNA test. If you had, say, 3 good suspects, and one of them had a DNA match, then that was very good evidence against that suspect. Unfortunately, sometimes it was used the other way. They'd start with the DNA, match it against whatever samples they had on file, and if they got a match, they'd go after that person. That's bogus.
If you look into the science behind much police investigation, you get this strange feeling you've fallen through some kind of wormhole and gone back to the early 19th century. It's amazing how much in common use has not been rigorously tested and peer reviewed by real scientists.
What is probably the single most annoying thing about fire investigation- from the investigator's perspective- is that arson is a terribly difficult crime to prove. Without a witness or some form of photographic or video evidence where an individual physically lights something on fire, the crime of arson is difficult to prove. As an instructor long ago put it to us: A man walks into a structure, and then walks back out. Later, it catches on fire. Houses burn all the time- bad wiring, gasoline stored near a gas water heater, cigarettes left burning. But causality- that that fire was intentionally set, and was set by that individual- may be difficult to prove.
In that regard, arson can be more difficult to prove than murder. With murder, there is frequently trace evidence with everything from blood droplets to weapons used, that can associate the murderer with the crime. With arson, in many cases there is heavy fire, smoke, and water damage, as well as the difficulty in proving that a fire started intentionally versus accidentally. Trace evidence such as gasoline found on the shoes of the accused arsonist can often be explained by more mundane events, such as spills at a filling station.
Making things worse, the folks who investigate are often poorly- or incorrectly- trained, and sometimes don't even want the job. Things are changing and candidates are frequently better educated than they have been in the past, but it's still a little rough around the edges. There aren't too many investigators in the field with advanced degrees, and a week or two of schooling (Arson I and II) at a state fire academy or the National Fire Academy are considered enough to get to work in many cases. 40 hours of fire investigation training, and you can help in putting people behind bars for what is considered a heinous crime such as arson of a habitable structure.
Sometimes investigation doesn't even start with the fire itself. Financial records are often scrutinized to determine if the accused would benefit financially. Business not doing well? Maybe it was torched. Home being remodeled? Maybe a convenient excuse to collect on insurance because of some major construction issues that existed. Upside down in your auto loan and gas hit $3 a gallon? That Yukon sure burns good!
Put all these together, and it's little wonder that some of the folks accused and convicted of this sort of thing are convicted and jailed. Many are poor, and get lousy lawyers- juries are likely to convict on scant evidence when the alternative is to let a possible firebug out on the streets.
Fortunately, there are improvements, and the standards for training have gone way the heck up in past years. Certification under some standard for training is often required for the job, as well as continuing education to stay on the job. Engineers, chemists, modelers, and physicists tackle some of the more difficult issues with lab tests to back up what's being said in court. It's one thing to say that a steam pipe at X degrees for Y years can eventually cause enough pyrolysis of nearby wood to create open flame; it's another to have some PhD back it up with experiments that prove it, possibly exonerating the accused.
Sometimes folks believe strange things from way the heck back in their training. This is part of the legend behind "spontaneous human combustion." The '921 says in it somewhere in a straightforward (and vaguely comforting) manner that humans do not spontaneously combust. Now only if we can do that with the other bits of legend that investigators have clung to over the ages.
Here is some interesting information from a book on my shelf on Arson:
From: Fire Investigation; DAÉID, NIAMH NIC; CRC Press, Boca Raton, FL, USA, 2004. ISBN: 0-415-24891-4
(Excerpt: Chapter 1)
AIT: Automatic Ignition Temperature (as in 451 Fahrenheit)
In general, if arson investigation used to be like TFA states, then yes, I'd say that it has come a long way baby
In the Netherlands, most houses are concrete/brick based. And they are very energy efficient, because there are two walls, the space between them being filled with insulating foam.
Bert
IMHO, the difference in building materials can mostly be explained by the differences in the buildings.
Americans typically live in small, freestanding, single-family houses. For such small buildings, a wood+drywall construction is probably the most cost-efficient, especially considering North America's plentiful supplies of lumber. On the other hand, Europeans tend to live in apartment buildings, which require the use of stronger materials like brick, cinder block, and reinforced concrete.
Unfortunately, these rational choices of construction materials have become cultural values. Thus wealthy Americans are happy to buy enormous mansions made of toothpicks and cardboard, while some Russians I know are spending their meager resources on building small single-family homes out of concrete.
As was said earlier, it's damn near impossible to get an arrest for arson, much less a conviction. We had a guy admit to trying to torch his car for the insurance. He even wrote a confession and signed it, in front of my father and sheriff's deputies, and the DA let him off.
Arson investigation is grueling, filthy work. Hours on hours of rooting around in the rubble that was someone's home or business; sorting out the evidence from the disaster.
Fellow nerds, even though this shows that fire investigation is still an evolving science, go thank a firefighter or investigator for their service anyway. It'll make their day.
"Slapping lipstick on a pig does NOT make it Natalie Portman. Paris Hilton, maybe, but not Portman." - UncleTogie
Where the most striking case is the appartment block where they used aluminium panelling to cover the outer walls.
Hey, a tinfoil house!Many of you across the pond won't be familiar with this disaster, but it's as good an example of fire spreading quickly without accelerants as you'll ever see. It all started when someone dropped a cigarette, and within a few minutes a hundred-metre long wooden stand was a goner, killing dozens of people. There's a video of it on YouTube, although I should warn you that there's one or two scenes in it which I personally find slightly difficult to watch.
I wonder why my European parents have a wooden house (wooden frame filled with stone wool and covered with wooden planks, built in 1998), why their neighbours save one have also wooden frame houses, the oldest one being from 1654 (yeah, that's more than 350 years ago), why 25% of Germany's area is covered by forests, why Europe is in fact increasing its forest area, why towns like Quedlinburg or Erfurt are declared UNESCO cultural inheritance for their timber frame town centres, where all those pittoresce Black Forest and Bavarian rural houses come from, why we talk about "balconies" (which is just the german word Balken = timber).
Wood is a very common material in residential construction in Germany, and in fact its usage has increased with the larger number of prebuilt houses being built here.
I trained in 1979ish and then they were teaching how to fight flashover. One exercise involved a fully-involved brick "bedroom". Flames were up to the ceiling and spread across the entire room. The test: Put out the fire with a 1-2 second wide spray from a 2 1/2 inch hose. That's about 10-20 gallons of water.
The trick is don't spray the hay, spray the ceiling over the hay - that's where the heat is. This is opposed to the conventional technique of spraying "the base" of the fire.
The near-explosive boiling of water to steam takes away a coupla hundred degrees of temprature, and the sudden increase in humidity reduces the flame potential of aerable fuels like cloth, blankets, hay, etc ("aerable" as opposed to dense fuels like solid wood). The snuff-out is impressive.
I don't think the article is right about this being "new", although it's possible the info spread slowly in different regions.
Pavlov wouldn't be so famous if he'd used a can opener instead of a bell.