UNIVERSITY PARK, Pa. — Imagine grains of sand falling from above, slowly creating a pile. Most times, each granule will cling to the growing pile. Rarely, a single falling piece will cause the pile to shift. Even more rarely, a catastrophe will occur, completely reshaping the mound.
That’s how Danish physicist Per Bak in the 1980s explained how complex behaviors in nature can occur from simple origins. The self-organized criticality concept, which follows a power-law distribution, governs nearly everything in nature, from landslides to biology to social sciences. It’s called “self-organized” because the same pattern will form, even if the parameters change. For example, the pile of sand will follow the same pattern, even if the size or flow of the sand grains change.
Power-law distribution refers to how occurrences can be tied to one another. To use the analogy of the falling sand, if every 1,000 drops of sand create ten minor and one massive slide, that would lead to 20 minor and two major slides if 2,000 grains of sand were dropped.
And, according to research by John Mauro, professor of materials science and engineering at Penn State, this concept explains accidents in the workplace and how best to minimize them.
Mauro led a team that analyzed more than 600,000 workplace safety incidents from 28 different labor fields gathered by the U.S. Bureau of Labor Statistics and found self-organized criticality correlations for all categories.
“We found a power-law distribution for every single one of these labor fields even though these are all independent of one another," said Mauro. “We found the same patterns in many labor fields from mining to the entertainment industry so it does indeed follow self-organized criticality regardless of the particular work sector. Accident data does follow that power-law distribution, which also means that all of these accidents have the same underlying cause.”
That means serious workplace safety incidents have the same cause as minor ones, said the researchers. Simply put, if you want to minimize serious workplace disasters, you need to minimize minor offenses and the things that cause them.
Anecdotally, that’s a concept that’s been around for decades. Yet, until this research, researchers haven’t been able to add credence to Herbert William Heinrich’s Safety Triangle, which was created in the 1930s.
“It’s all governed by the base of the triangle,” Mauro said. “How do we improve the culture of safety where workers pay attention to the little things, the things like the housekeeping of the lab and wearing proper protective clothing? Because it’s those little things that lead to more serious accidents. If you can lessen the number of minor accidents, you bring the whole distribution down.”
The team's research appears in the journal Physica A: Statistical Mechanics and its Applications (PHYSICA A).
Mauro said he’s long been interested in how self-organized criticality can be applied to other areas of science but a recent safety talk between colleagues from Penn State and Corning, where he worked until 2017, caused him to take a deeper look.
“I had a hunch that this could also apply to safety because that’s what we really care about,” Mauro said. “We don’t want anyone to get hurt even if it’s a minor incident, but what we really care about are major accidents. That hunch turned out to be correct.”
Mauro is a glass expert but he also wants to bring his industry experiences to Penn State. That’s why he became interested in this research and why he’s taken a seat on Department of Materials Science and Engineering’s safety committee, which for decades has focused on improving laboratory safety and giving students proper safety training.