Every time an at-risk behavior occurs, someone is exposed to potential injury. The more often this behavior occurs and the more people performing it, the greater the exposure. For example, lifting a load greater than 40 pounds might not be very risky if done once, but multiply this risk by numerous employees making several lifts per day and you gain a different perspective.
Duration also contributes to risk exposure. The longer one carries a 40-pound load, the greater the exposure. The longer one resists using PPE, the greater the exposure. Conversely, one brief instance of donning certain PPE, from a hard hat to a vehicle safety belt, reduces risk exposure for the entire duration of usage.
What’s the probability that a behavior will result in an injury? Consider the act of lifting. By counting people and daily opportunities to lift per person, you can get a good estimate of exposure. But how probable is it that lifting a load greater than 40 pounds will cause a back injury or any severity? Many factors come into play – the age and physical strength of the lifter and various behavioral aspects of the lift. When lifters hold the load close and bend their knees, the probability of a back injury is greatly reduced.