Don’t Get Blinded by Your Injury Numbers

Injury Numbers

What we are measuring is not safety but unsafety” Craig Marriott in Challenging the Safety Quo.

Many companies…continue to measure their systemic safety by the lost time frequency rate…Unfortunately this reflection of personal injury rates provides little or no indication of a systems liability to a major hazard disaster.” James Reason in The Human Contribution: Unsafe Acts, Accidents and Historic Recoveries.

Managers who don’t know how to measure what they want settle for wanting what they can measure.”  Ackoff, Addison and Carey in Systems Thinking for Curious Managers.

The Numbers Game

We in safety, and in management as well, are often consumed by our injury numbers and rates.  The lower the better.  So low in fact that zero injuries/harm has become the goal of many organizations.  Often our bonuses, and even our jobs, depend on keeping those injury numbers low.

In some ways our focus on driving down injury rates has been a stunning success.  The Total Recordable Injury Rate (TRIR) in the US is at an all-time low.  Very many large organizations now go for long periods of time, sometimes years, without recording a lost-time injury.  Before we break out the pizza and party hats, however, we need to consider the disturbing fact that workplace fatalities are actually increasing.  The over 5,300 work related deaths in 2019 were the most in a dozen years and the fifth time in the last six years that we have seen an increase in the fatality numbers.

Are we over emphasizing personal injury incident rates at the expense of less frequent but more serious incidents?  Is the relentless quest for ever lower injury numbers and zero goals suppressing incident reporting and leading us to manage the numbers rather than the holistic management of safety?  Are we fudging the injury numbers to keep them lower than they really are?  I have come to believe that the answer to all these questions is yes.  But are low TRIRs indicative of low risk for serious incidents and fatalities?  There is now considerable evidence that the answer is no.  Perhaps a few notorious examples will help illustrate my point.

They Thought They Were Safe

Texas City: Immediately prior to the 2005 Texas City refinery explosion that killed 15 and seriously injured nearly 200 others, therefinery’s reportable incident rate was at an all-time low and was just one third of that for the industry as a whole.  The refinery had received numerous safety awards and increased bonus pay because of their low injury numbers and rates.  Ironically and sadly, many of the workers killed in the explosion had just returned to their workstation after attending a luncheon celebrating their “excellent” safety record.

Subsequent incident investigations, however, found widespread and longstanding safety weaknesses including unworkable and unfollowed procedures, deferred maintenance on safety critical equipment, a tolerance for production to trump safety and a culture of “blindness to major risk.”  The incident resulted in record OSHA fines and the termination of six workers and four facility managers.

Deepwater Horizon: Before the Deepwater Horizon explosion that killed 11 and triggered the largest accidental oil spill in history, the platform had experienced seven years without a lost-time injury.  The platform had also received at least 15 awards for their low incident rates.  As was the case for Texas City, the Deepwater Horizon was holding a safety celebration the day of the explosion.

The final incident investigation found nothing to celebrate, however.  “These failures …. appear to be deeply rooted in a multidecade history of organizational misfunction.”  The associated fines and compensation will likely run over $50 billion.

Laporte Texas: DuPont has long been noted and praised for its exceedingly low incident rates.  In 2013, the company was awarded the National Safety Council’s top safety award and praised for its commitment to safety.

In 2014, four DuPont employees at the company’s Laporte Texas plant were killed via chemical exposure.  The subsequent incident investigation landed DuPont in OSHA’s severe violator enforcement program and prompted this quote from OSHA head, David Michaels: “The four preventable deaths and the very serious hazards we uncovered at this facility are evidence of a failed safety program” and “a broken safety culture.”


The point of this article is not to say that your incident rates are not important.  They are.  But we need to understand their limitations.  Just to mention a few:

  1. TRIRs are often not reliable, especially when low rates are used as organizational goals.  It is simply too easy to fudge these injury numbers.  OSHA estimates that 50% of reportable incidents go unrecorded.
  2. Incident rates are subject to normal statistical variation, especially for smaller organizations and for infrequent events such as lost times.  Action should not be based on statistical anomalies.
  3. Low TRIRs can lead organizations to develop a false sense of security (see examples above).
  4. Luck (good or bad) can skew your rates, especially when safety data sets are relatively small.
  5. TRIRs are very poor predictors of serious injury and fatality risk. There is scant evidence of correlation between low incident rates and low rates of severe incidents and fatalities. And lastly,
  6. Incident rates do not measure safety.  They measure the absence of safety.  Measuring what you are proactively doing to create safety (leading indicators) are far better measures of safety performance.

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Jim Loud

Mr. Loud’s over 40 years of safety experience includes 15 years with the Tennessee Valley Authority (TVA) where he served as the supervisor of Safety and Loss Control for a large commercial nuclear facility and later as manager of the corporate nuclear safety oversight body for all three of TVA’s nuclear sites. At Los Alamos National Laboratory he headed the independent assessment organization responsible for safety, health, environmental protection, and security oversight of all Laboratory operations.

Mr. Loud is a regular presenter at national and international safety conferences. He is the author of numerous papers and articles. Mr. Loud is a Certified Safety Professional (CSP), and a retired Certified Hazardous Materials Manager (CHMM). He holds a BBA from the University of Memphis, an MS in Environmental Science from the University of Oklahoma and an MPH in Occupational Health and Safety from the University of Tennessee.


Ackoff, R. L., Addison, H. J., Carey, A., & Gharajedaghi, J. (2010). Systems Thinking for Curious Managers. Amsterdam University Press.

Marriott, C. (2017). Challenging the Safety Quo (1st ed.). Routledge.

Reason, J. (2008). The Human Contribution: Unsafe Acts, Accidents and Heroic Recoveries (1st ed.). CRC Press.

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