The Severity Index and what it means for your safety helmet

June 7, 2022

Though not a traditionally used metric in the safety industry, the Severity Index is a strong performance indicator that’s widely used in the sports industry for helmet safety, selection, and improvement.

So why might this specific metric be important to know when it comes to your industrial safety helmet?

For us, it’s simple – the Severity Index is another way to measure safety performance, especially when it comes to protecting one of your biggest assets, your head.

Because we are constantly innovating and pushing our PPE technology to the next level, we tested our all-new technology, the Kinetix™ suspension system within our Ceros® XA250 safety helmet, against the Severity Index and found some amazing results.

But first, here’s what you need to know about this head safety performance method.

Head injuries in the workplace

To understand how the Severity Index (SI) is related to head protection in general, we need to first talk about traumatic brain injuries, or TBIs on the job.

Despite safety helmet standards on most worksites, there are still incidents of TBIs that send workers to the hospital each year. And depending on the severity of the injury, TBI-related health problems can last a few days or the rest of the injured person’s life – or worse. Between 2003 and 2010, there were 2,200 fatalities from TBIs in construction alone.

Because TBIs are so significant with workers, we dove into learning more about mitigating these kinds of head injuries with alternative head protection standards like the SI.

That’s because the SI was developed as a method to predict the possibility of traumatic brain injury in sport helmets by the National Operating Committee on Standards for Athletic Equipment (NOCSAE), a leading source for concussion-specific research funding in sports medicine and science for more than 20 years.

Here’s how the Severity Index works

More specifically, the SI measures a helmet’s ability to reduce impact forces to the head – and has been proven to help lower traumatic brain injuries resulting from impacts on the field of play, in sport specifically.

It does this by contemplating two factors:

  1. Accelerations
  2. How much these accelerations last during an impact event

Or simply put, it looks at the force and time of an impact to assess head injury risk that can be replicated across laboratories and under different impact scenarios. The result is expressed simply as a number with no units of measurement, and lower scores are a better indicator of reducing trauma.

The SI value tends to vary from impact to impact because it places more emphasis on the duration of the impact than the peak acceleration force. In general, head injury tolerance improves as the duration of the impact increases.

How HexArmor® uses the Severity Index

In terms of the safety world, we have found that the SI is a helpful metric to predict safety helmet performance in conjunction with ANSI/ISEA standards, as it contemplates impact accelerations and decelerations during an event, or time in general. Plus, we have noticed differences between our technology and others on the market.

So far, we’ve used the SI methodology as additional validation to analyze impacts on our Ceros® XA250 industrial safety helmet with Kinetix™ suspension technology.

Here's how we compare to market leaders:


Please note: The performance criteria for head protection as provided in the ANSI/ISEA Z89.1 standard is still our number one goal to achieve with all of our safety helmets, and the SI has only been used as an additional metric to showcase safety helmet suspension performance in select safety helmet models. The SI is not a mandated performance indicator for industrial safety helmets.

HexArmor® can help

Our patented, innovative Kinetix™ suspension system was found to drastically excel beyond the competition by delivering a staggering average performance improvement up to 120% when tested against hot temperatures.

How? Kinetix™ acts like a simple machine to not only dissipate peak impact force but also lengthen the time of the event, thus reducing the severity of the impact.

What’s more, Kinetix™ tested twice as safe as the ANSI/ISEA impact protection requirement for Type 1 safety helmets relative to force transmission, making this suspension system truly one of a kind, delivering some of the highest levels of protection in its class.

Let us know if you have questions or would like to start a trial - our Solution Specialists are ready to work with you. Call 1-877-MY ARMOR or send us a message.

Learn more about Kinetix™ technology

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