by Brianna M. Eiter, Jonathan Hrica, Jennica Bellanca, William Helfrich and Jason Navoyski
Researchers at the National Institute for Occupational Safety and Health
(NIOSH) are studying how stone, sand, and gravel (SSG) mineworkers
identify and understand hazards in their work environment. This is the
last article in a three part series (see the December, 2016, and March,
2017, North American Quarry News issues). In
this article, we discuss risk assessment, which is how an individual
reports how risky a situation is. It is critical to study how
mineworkers assess risk, because research shows that risk assessment
influences safety related decisions on the job (Hunter, 2002).
Understanding how mineworkers assess risk is an important step towards
determining not only how they identify and evaluate hazards, but it is
also critical to understanding how they make decisions about how and
when to mitigate hazards at mine sites.
To study risk assessment, we asked mineworkers and safety
professionals to assess the risks associated with numerous hazards found
at a surface stone mine site. This article presents an overview of our
risk assessment task, how safety professionals and mineworkers used it,
and our suggestions for improving risk assessment at mine sites.
Risk assessment task and measure
The purpose of the risk assessment task was to determine whether
experience affects how mineworkers assess risk. Thirty-five participants
took part in the study; this included 11 new mineworkers (less than two
years of experience), 11 experienced mineworkers (more than two years
of experience), and 13 safety professionals (more than two years of
experience in environmental, health, and safety positions). After
completing the NIOSH hazard recognition task described in part two of
this series, participants reviewed all 102 hazards with researchers
during a debrief. Participants were given feedback on which hazards they
had identified and missed. While going through this feedback, we asked
participants to make a risk assessment for each hazard, regardless of
whether they identified or missed it (see Figure 1).
To measure risk, we used a risk assessment measure previously used in
the construction industry (Perlman et al., 2014). Using this measure,
participants made a decision about the (1) accident severity, (2)
accident probability, and (3) overall risk level for each hazard (see
Figure 2). For each risk assessment, we instructed participants to use a
scale from one to five to rate each component based on what was shown
in the panoramic images. Participants were asked to go with their first
instinct and make their decisions as quickly as possible. They were also
given the following detailed explanation for each of the components:
- Accident Severity: For this component, participants were told that
severity is how severe they thought the likely resulting accident would
be;
- Accident Probability: For this component, participants were told
that probability is the likelihood that an accident would occur; and
- Risk Level: For this component, participants were told that risk level is their overall risk assessment for a hazard.
Risk assessment results
The results of the risk assessment task show that there is a great
deal of variability across ALL levels of mining experience and ALL
components of risk. This was true even for safety professionals who have
more experience and training in assessing risk. This variability is
illustrated using electrical and material handling hazards as examples
and is evident by the long length of the error bars in the graphs in
Figures 3 and 4. Specifically, the two point range for electrical
severity (see Figure 3) indicates that mineworkers’ ratings ranged from a
minor injury with leave to a fatal injury. This variability suggests
that there are differences in how mineworkers assess risk, independent
of experience.
However, experience level was shown to affect risk assessment ratings
for hazards in specific accident classifications. Electrical and
material handling hazards provide a good comparison because of their
differences in severity and accident probability, as represented in the
MSHA fatal and non-fatal days lost (NFDL) data (incidence of
metal/non-metal mining accidents by classification for years 2009-2015).
Injuries attributed to electrical hazards do not happen frequently;
however, when they do happen, they tend to cause fatal or more severe
injuries (see Figure 5). In contrast, injuries attributed to handling
materials hazards happen far more frequently, but typically do not lead
to as-severe injuries.
For electrical hazards (see Figure 3), the relative difference in the
risk assessment components agree with the trends in the MSHA data. On
average, participants at all experience levels rated electrical hazards
higher for accident severity than for probability. However, the severity
and probability ratings for handling material hazards (see Figure 4) do
not align with the MSHA data. While injuries from handling material are
frequent in the MSHA data, participants’ accident probability
assessments do not reflect that they understand just how often these
injuries occur. Accident probability assessments were approximately the
same as accident severity assessments for all participant groups.
Interestingly, when comparing accident probability ratings across
accident classifications, safety professionals rate handling material
hazards higher than electrical hazards. These results indicate that, in
general, ALL participants understand the potential consequences of an
accident. For accident probability assessments, only the safety
professionals are also able to recognize differences in the likelihood
that an accident will occur.
Risk assessment summary
A mineworker’s ability to assess risk is critical for health and
safety at the mine site because this ability has been shown to affect
hazard mitigation, for instance when to use PPE or when to de-energize
and lockout a piece of equipment (Hunter, 2002). The results of the risk
assessment task indicate that not all mineworkers see and understand
hazards in the same way. First, there is a great deal of variability
found within the risk assessment scores, even across experience levels.
One explanation for this finding is that there are differences between
people. These individual differences can be attributed to varying
knowledge of worksite hazards, specific experiences, or differences in
how much risk they tolerate. One way to minimize the effect of
mineworker differences on risk assessment ratings is to standardize the
procedure they use when assessing the risk associated with a hazard.
Whether it is MSHA’s SLAM Risks
(https://arlweb.msha.gov/SLAMRisks/SLAMrisks.asp) or another risk
assessment program, making sure all mineworkers are using the same
procedure and scale should help reduce variability.
The results of the risk assessment task also suggest that, while all
participants understand accident severity (the consequences of the
hazard), only the safety professionals exhibited some understanding of
accident probability (how likely it is that an injury will occur). While
understanding severity is important, especially for hazards that can
lead to fatal injuries, it is also important to recognize how often
injuries can occur. Frequency increases the overall risk, especially for
less severe hazards (e.g., handling material hazards). Increased risk
may prompt workers to immediately mitigate the hazard or stop work as
opposed to just reporting it to be fixed later. Overall, understanding
severity and probability can affect how and when mineworkers mitigate
hazards.
Finally, during the study, we asked participants whether they had
received risk assessment training. Although the majority of the
participants (29 out of 35) reported receiving some type of risk
assessment training, it became evident during the debrief that most
mineworkers did not have a lot of experience making these assessments.
In order for experienced and inexperienced mineworkers to assess risk as
effectively as safety professionals, especially for accident
probability, it is critical for them to practice making risk assessments
and understand how probability and severity affect overall risk.
What can you do now?
- Standardize your risk assessment procedure by using a risk
assessment program such as MSHA’s SLAM Risks or the risk assessment
measures included in this article.
- Make sure all mineworkers understand and use probability and severity to assess risk.
- Use MSHA fatal and NFDL data to talk about how often injuries occur to increase mineworkers’ understanding of probability.
- Have your mineworkers practice making risk assessments using probability and severity.
To practice making risk assessments, choose an accident category
(e.g., slips and falls) and come up with ways that the work environment
can change that would result in changes in accident severity or
probability. For instance, debris on a walking path at ground level may
result in minor injury. However, the probability of that injury
occurring depends on where the debris is located. A mineworker is less
likely to trip over debris if it is in a brightly lit walkway than if it
is immediately behind a doorway they are entering.
Upcoming NIOSH work
NIOSH is using research related to hazard recognition and risk
perception among stone, sand, and gravel mineworkers to develop a
workplace examination training and assessment tool. This tool will be a
Microsoft Windows® application that can help mine operators evaluate
mineworkers’ ability to perform workplace exams as well as provide a
platform to practice recognizing hazards and performing risk
assessments. This training tool will be available to all stakeholders
through the NIOSH website in the upcoming months. We will begin testing
the training tool soon. If you are interested in evaluating the training
tool, or if you have any questions, please contact Brianna Eiter
(BEiter@cdc.gov). To learn about other ongoing NIOSH research studies,
visit our website at www.cdc.gov/niosh/mining .
Disclaimer: The findings and conclusions in this article are those of
the authors and do not necessarily represent the views of NIOSH.