Pig farming is tough, foul-smelling, and dirty work. Turns out, that's the good part of it. See, since 2009 the American hog farming industry has been struck with an explosive pork poop problem—in that the decomposing porcine waste will go boom under the right conditions.
Since the phenomenon was first described four years ago, a half dozen such explosions have occurred throughout Iowa and Minnesota, stumping scientists as to the cause. The largest explosion killed all 1,500 hogs at the site and seriously burned a farm hand. Another lifted a barn "a couple of feet off the ground," according to University of Minnesota researcher David Schmidt.
Methane is a normal byproduct of pig, cow, and sheep waste and, in well-ventilated areas poses no combustion threat so long as it doesn't exceed a concentration of 20 percent. But for some as-of-yet uncovered reason, the shit pits utilized in industrial hog farming operations—subterranean holes located under the pens and covered by slotted planks that allow poo to fall through, collect, and decompose—have begun developing a thick matte covering of bacterial foam, the consistency of whipped egg whites.
This layer of foam can grow to four feet thick, covering a highly-volatile layer of 60-70 percent concentrate methane gas beneath it. If the foam is agitated, it suddenly releases the combustible gas and, in the presence of an energy source—a heater or lit cigarette—the gas will ignite with terrible results. Researchers suspect it may be bacterial based as the phenomenon grows quickly once established and could be instigated due to dietary or environmental changes. But until then, you're going to want to refrain from smoking in the hog barn. [Mother Jones, Iowa Pork via TreeHugger]