Professional development

Math for safety pros

How can it make you more effective? Let us count the ways


Photo: gorodenkoff/iStockphoto

Wherever safety professionals turn, math is a needed skill.

“I use it constantly. Every day. Everything I do is data driven,” said Todd William Loushine, an associate professor in the University of Wisconsin-Whitewater’s Department of Occupational and Environmental Safety and Health. “It’s essential to problem-solving.”

Colin Brown, director of business advancement for the Board of Certified Safety Professionals, said safety pros “need to use various math concepts for managing risk; analyzing data and metrics; ensuring regulatory compliance; and applying technical knowledge in areas such as fall protection, industrial hygiene and ergonomics.”

Math skills also can help tell a story, make a case for budget increases and demonstrate the effectiveness of safety efforts.

Where safety meets math

“What are the duties of a safety professional? Evaluate, anticipate and audit.” Loushine said. “It requires you to understand and collect data and be able to analyze it.”

Knowing how to calculate your organization’s DART (days away, restricted or transferred) rate or TRIR (total recordable incident rate) is an important first step. (See “How math meets safety” below.)

The specific industry you work in will determine what other calculations are necessary.

“Some industries, such as manufacturing and construction, will require knowledge of complex or advanced math and science principles,” said Angela Giotto, director of research and product development for BCSP. “For example, storage capacity, rigging and load calculations, ventilation and system design, noise hazards, heat and cold stress, and fall protection.”

Other important math calculations, according to Loushine and BCSP experts, can involve:

  • Slips, trips and falls
  • Velocity and acceleration
  • Lift plans
  • Confined space entry
  • Ladder and lift equipment selection
  • Personal protective equipment decisions
  • Braking systems for robots
  • Arc flash calculations
  • Dispersion of airborne contaminants

“Every company, industry or job has different hazards,” Giotto said. “It’s our job as safety professionals to determine how to mitigate the hazards.”

When working with students, Loushine makes sure math assignments have context.

“If we have to do some calculations, it’s either a case study or a lab assignment,” he said. “Every calculation needs to have a story either before it or embedded in it.”

How math meets safety

Here are five common math calculations that safety professionals use on the job:

Total recordable incident rate

TRIR =(Number of cases multiplied by 200,000) divided by (total number of employee hours worked by all employees in the given population)

According to the National Safety Council, the 200,000 factor remains constant even if rates are calculated for only part of the year, such as monthly or quarterly.

Days away, restricted or transferred rate

DART rate =(Number of recordable injuries and illnesses resulting in days away, restricted or transferred multiplied by 200,000) divided by (total hours worked by all employees)

This calculation, which is mandated by OSHA, helps employers know how many workplace injuries and illnesses have caused workers to miss days on the job, perform restricted activities or transfer to another job annually.

Time-weighted average

TWA =(Sum of portion of each time period multiplied by levels of substance/agent present during time period) divided by (hours in the workday – usually 8)

Workers are often exposed to varying concentrations of noise or a contaminant throughout their workday, according to NSC, rather than a steady, uniform concentration.

NIOSH lifting equation

Recommended weight limit (RWL) =LC (weight of the object lifted) multiplied by HM (horizontal distance of hands from midpoint between the ankles) multiplied by VM (vertical distance of the hands from the floor) multiplied by DM (vertical travel distance between the origin and the destination of the lift) multiplied by AM (angle of asymmetry – angular displacement of the load from the sagittal plane) multiplied by FM (average frequency rate of lifting measured in lifts per minute) multiplied by CM (a value derived from lifting frequency and vertical displacement of the lift)

For many safety pros, the best way to calculate RWL is by using NIOSH’s lifting equation mobile app, known as NLE Calc. Learn more at the NIOSH website.

Cost-benefit analysis

This calculation compares costs by dollar (direct, indirect, intangible and opportunity) with benefits (direct, indirect, intangible and competitive).

Speaking the language of the C-suite, especially on how dollars spent positively impact safety, is an invaluable tool.

Not sure you got it right?

The data is in hand. The calculations are done. But don’t stop there, advises Giotto.

“The key to any new skill is to practice, and math is no different,” she said. “It’s important to build the foundation and understand the fundamentals of math before moving on to more complex problems.”

If you’re still not sure you’ve “done the math” right, don’t fret. Resources are available to help.

“Reach out to peers, supervisors, corporate resources or even consultants,” Giotto said. “Beyond access to academic resources, building a network of safety practitioners is an invaluable tool to have when you encounter situations where you might not be an expert.”

If you’re developing reports for regulatory agencies and are concerned about calculations, Giotto recommends you put your network of resources to good use.

Resources to master math

Keeping your math skills strong can be accomplished with just a few clicks of the mouse or a visit to a safety and health conference.

Available resources include, where anybody with workplace safety responsibilities “can access BCSP certification exam blueprints and references created by credentialed subject matter experts,” Brown said. “These blueprints and references reflect the most current knowledge and skills required to keep people safe.”

Additionally, the National Safety Council’s “Accident Prevention Manual – Administration & Programs” contains various calculations that can be used by anyone with safety responsibilities.

NSC also conducts live events that feature math activities. The 2023 NSC Safety Congress & Expo – set for October in New Orleans – includes certification courses that will focus on math needed for the exams.

At work and off the job, math is always present for Loushine.

“I drive a hybrid vehicle and I’m constantly watching the braking percent,” he said. “It’s really nerdy, but I’m always doing some form of calculation.”

Sometimes that’s using his phone or a calculator that’s almost always by his side.

“Having a means to collect data and then analyze it allows you to improve,” Loushine said. “You’re identifying what can be improved next in order to get gain.”

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