Key Takeaways

- Serious injuries and fatalities (SIFs) continue to occur despite efforts to reduce overall incident rates.

- SIFs such as combustible dust explosions are often caused by events that are considered to have a low likelihood of occurrence but result in high-severity consequences.

- Combustible dust explosion risks are often underestimated by organizations partly because the occurrence of such events is infrequent, giving a false sense of security.

- This article uses a combustible dust case study to demonstrate how such low-likelihood, high-severity risks can be assessed for their true risk potential.

Often, risk assessment efforts within an organization are targeted based on the organization’s past experiences, incident frequency trends and activities that present obvious dangers. These are all important sources of information that can help identify areas that need assessment and treatment. But what about serious or catastrophic risks that occur less frequently? Organizations have limited resources and can overlook such risks due to their infrequent nature. Unfortunately, low-likelihood, high-severity risks such as fires, environmental releases and natural disasters can result in serious injuries and fatalities (SIFs), and severely impact an organization. To emphasize this point, one can look at recent incident trends. While incident rates have decreased over the past decade, SIFs have experienced a slight increase. According to the U.S. Bureau of Labor Statics (BLS, 2020), 5,333 fatal work injuries were recorded in the U.S. in 2019, a 2% increase from the 5,250 in 2018. This might suggest that risk-reduction efforts have been more concentrated or more effectively applied to higher frequency type risks than those that produce SIFs.

Combustible Dust Risks

As described by OSHA (n.d.), any combustible material can burn rapidly when in a finely divided form. Dust from organic matter (e.g., grain, wood, plant fibers) as well as dust from inorganic materials (e.g., iron, glass, ceramic) will burn in the right conditions. If such a dust is suspended in air in the right concentration, it can become explosible under certain conditions. Even materials that do not burn in larger pieces (e.g., aluminum, iron) can be explosible in dust form given the proper conditions (OSHA, n.d.).

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