You're not seeing, for instance, the weeks of hard work in even harsher conditions that led up to this rare down day. And you're not seeing the decades of research that helped establish policies requiring rest and relaxation after a long hitch of long days.
“It's not random,” said Brian Sharkey. “There is a considerable amount of science on long work shifts and long assignments.”
Before that, Sharkey was an exercise physiology professor at the University of Montana, where he explored firefighter safety from 1964 until his retirement in 1997. In fact, he said, firefighters were integral to his years at UM. Part of the job description he accepted back in 1964 was to coordinate a cooperative research agreement between the Forest Service and the university.
Since then, he's spent a whole lot of summer months in and around fire camps, strapping all sorts of contraptions to firefighters in hopes of measuring physiological performance under various conditions.
Others, too, have explored human capacity for work, and Sharkey acknowledges “there is a whole literature out there on fatigue, and on how long work shifts affect human performance.”
But not every study is created equal, and Sharkey's are distinguished by their real-world focus on wildland firefighters. His isn't research; it's field study, aimed at implementation on the ground. And it's important, he said, because it gets right at worker productivity, as well as firefighter safety.
In some studies, he said, researchers have asked subjects to track a moving ball across a computer screen with a mouse. After 12 hours, they're categorized as “fatigued.” After 24, they're the equivalent of legally drunk.
Problem is, he said, “it's not real work, and people get bored much faster when the task is meaningless.”
Also, the results of those tests did not emphasize that the fatigue wore off as the day wore on.
“From 2 a.m. to 6 a.m. your body doesn't want to do anything,” he said, adding that other research shows a 24-hour shift can be worked safely if there's a nap during the “drunken” wee hours.
Those sorts of measurements surely show how quickly people become fatigued and distracted, but they aren't much use in real-world situations, he said.
A better fit, Sharkey said, might be the military study that tested recruits completing “military-relevant tasks,” or what Sharkey calls “real work.”
Then, the soldiers were kept awake for four days with just two hours of sleep per day, and were given only half rations.
When tested again, “they performed nearly as well as they did at the beginning.”
The implication, to Sharkey, is clear: “Well-trained, highly-motivated people can work a long shift without any problem.”
And professional firefighters - elite Hotshot crews and smokejumpers, for instance - are surely well trained and highly motivated, moreso perhaps than their less-seasoned counterparts.
“But we wanted specific data on firefighters fighting fire,” he said. “Over the years, we've done it many different ways.”
Temperature changes. Heat stress. Energy use.
Recently, in conjunction with UM, Sharkey and others at the Missoula Technology Development Center looked hard at how prolonged work can suppress the human immune system, a known measure of physiological decline.
Specifically, they looked at what he calls “the first line of defense against upper respiratory infection,” called salivary immunoglobulin A (sIgA, in scientific shorthand.)
It's a good measure, he said, because upper respiratory infections, perhaps not surprisingly, are rather common among firefighters.
Turns out, sIgA declines considerably during a 14-hour shift, but bounces back to normal after a good night's sleep, at least in the Hotshots he studied. That work schedule, he said, “seemed to allow full recovery of the immune system.”
But after a 21-hour shift, it didn't recover. Even if you pulled one 21-hour shift and then went back to 14-hour shifts, it still didn't recover. The longer day, apparently, required a longer rest afterward - up to a full day of rest, in fact.
The results came from a relatively small data set, Sharkey admits, “but our data's better than anyone else's data. What we're trying to do is to put some meaningful numbers on something other people just call fatigue.”
And sure enough, his data have helped drive policy. Today, firefighters (usually initial-attack teams, smokejumpers and heli-attack crews) need multi-level approval to work more than 16 hours straight, and then the longer shift must be followed by adequate rest.
“That's when you see them killing time,” Sharkey said, “just waiting for the next meal. That's the only way the immune system can recover.”
Likewise, the work of Sharkey and others has helped change policy regarding the length of the hitch. Crews used to work up to 21 days in a row before taking a break. Now the limit's 14, with two days off required between each two-week stint.
“There's lots of science on assignment length,” he said, “but that is not necessarily what dictates policy.”
In fact, his observations have convinced him that, from a physiological standpoint, people can indeed work 21 days in a row. After all, for most of the past century fire crews worked three weeks on before taking a break, with no real consequences.
“But there's science and then there's common sense and reality,” Sharkey said. “We have to deal with reality.”
The reality is that social concerns are equally as important as physiological limits.
“Today, people don't want to be away from home for as long,” he said. “There are a lot of other pressures, a lot of single parents.”
There's this standing militia out there, he said, this army of volunteers with the skills needed to fight wildfire. But you can't force them onto the line, “and the likelihood of their making themselves available is probably much better with a two-week hitch than with a three-week hitch.”
He's measured all sorts of variables over the decades, “and our experience has been that these people aren't falling apart after 21 days. But there are other considerations, too.”
One of the considerations that was widely discussed back in 2000 - when the hitch was shortened from 21 days to 14 - was a supposed study indicating that injury rates went up after two straight weeks on the job.
“Well,” Sharkey said, “that may be true. But I could never find the study to back that up. I asked, but no one could produce it.”
Still, when the decision was made, part of the rationale cited was the supposed study measuring injury rates.
The science, then, is only one part of the R&R equation. The other parts are “social realities and pseudo-science.” Still, Sharkey remains a realist, and figures the 14-on, two-off cycle of 16-hour days is appropriate in today's world.
“You can't just work people and work people and expect them to keep coming back,” he said, “regardless of how capable the physiology is.
“There are pressures on us well beyond what the human body can endure.”
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