Yesterday I wrote about a U.S. Forest Service study that correlates a decrease in cigarette smokers to a decrease in wildfires caused by cigarettes. The study did not claim that the two were connected, but just noted that the trajectory of both–fewer smokers, fewer forest service fires–could be related.
Reader Pete Vanvuren, who is a wildland firefighter, sent me this email in response:
“I would have to say that the two are most likely unrelated. When a fire ignites near a road, people are pretty quick to jump to the assumption that ‘it must have been started by a cigarette tossed out a car window’. It is actually much more likely that such a fire was started by sparks from a lose tow chain dragging on the road, etc. There are very specific conditions of temperature, RH (Relative Humidity), available fuels, etc and then there are the outside variables of altitude, wind conditions, etc. that are required to get a tossed cigarette to actually start a fire…If there is a correlation between the cigarettes and wildland fires, I would suggest it have to do with the more common use of lower ignition propensity cigarettes.”
So, a lot of factors and “etcs.” when it comes to fire ignitions. Pete’s point seems to be that getting a cigarette to start a fire is not as easy as one would suppose.
I set out to answer that–exactly how does a cigarette start a fire? And what on earth is a “lower ignition propensity” cigarette?
For question one, I talked to Sara McAllister, a research mechanical engineer at the U.S. Forest Service Rocky Mountain Station’s Fire Sciences Lab in Missoula, Mont.
“Cigarettes burn in smoldering combustion mode,” McAllister said. “Even though you don’t see flames, it’s still hot.”
Cigarettes burn at about 1,100 degrees Fahrenheit. Dry grass only needs to be about 650 degrees to ignite–so a cigarette could do that easily. But, after a fire lights, how can you guarantee that the fire will spread? It all depends on the day, McAllister said.
“There are a lot of variables– fuel, weather, topography, all of the usual concerns from any ignition source,” she said.
Now, for question two: What is a low ignition propensity cigarette and why would it make a difference when it comes to wildfire/fire ignition?
For that, I spoke with Kristine Van Cleve, the Colorado Division of Fire Safety ‘s Fire Safe Cigarettes and Data Specialist.
Low ignition propensity cigarettes need to be inhaled for them to burn, essentially. If someone is not inhaling, then the cigarette will burn down to a certain point and snuff out.
“It’s kind of a safe guard, if they don’t inhale and it gets to that then it just puts the cigarette out,” Van Cleve explained. All cigarettes in Colorado are officially required to have a low ignition propensity certification, Van Cleve added.
So, if you fall asleep while smoking a low propensity cigarette, in theory it should go out before you come to any harm. In theory as well, if the cigarette gets tossed out a window into a patch of tinder-dry grass, it should snuff out.
McAllister, on the other hand, had never heard of such a cigarette.