More than 33 million U.S. homes put up a natural tree for Christmas but dry trees account for 250 fires annually, resulting in 14 deaths, 26 injuries and more than $13.8 million in property damage, officials say.
The Building and Fire Research Laboratory of the National Institute of Standards and Technology showed what happens when fire touches a dry tree. Within 3 seconds of ignition, a tree is completely ablaze, at 5 seconds, the fire extends up the tree and black smoke with searing gases streaks across the ceiling, while fresh air near the floor feeds the fire.
Sofas, coffee tables and carpet ignite prior to any flame contact and within 40 seconds "flashover" occurs -- an entire room erupts into flames, deadly toxic smoke engulfs the scene.
A well-hydrated tree is a different story.
NIST fire safety engineers selected a newly cut green Scotch pine, made an additional 2-inch cut from the trunk's bottom and watered it daily.
The fire engineers tried and failed to light the tree with a single match. They used an electric current to ignite the entire matchbook, but it failed to ignite the tree. Finally they applied a flame using a propane torch. The branches ignited briefly, but self-extinguished when the researchers removed the torch from the branches, the engineers say.