From The Ergoweb® Learning Center

User Anthropometry Not Always Considered in Crash Safety Testing

Heavier people are more likely to be killed or seriously injured in car accidents than lighter people.

While this certainly adds to the arguments for maintaining a health body mass index (BMI), a measure that takes height and weight into account, the purpose of this article is to illustrate that the actual user population is not accurately represented in crash safety testing.

According to a study published in Accident Analysis and Prevention, people weighing between 100 and 119 kg (220-262 lbs) are almost two-and-a-half times as likely to die in a crash as people weighing less than 60 kg (132 lbs). The study included more than 26,000 people who had been involved in car crashes.

Also an important finding was that the same trend held up when BMI was looked at, concluding that it’s not just total weight, but obesity that is dangerous. A BMI of under 25 is considered normal, while 25 to 29.9 is deemed overweight and 30 or more is obese. The study found that people with a BMI of 35 to 39 are over twice as likely to die in a crash compared with people with BMIs of about 20. You can calculate your BMI on the Centers for Disease Control (CDC) website listed below.

So how does this relate to anthropometry? Some suggest it shows that crash tests do not accurately reflect the people who may be driving the car. For instance, US car manufacturers have already had to redesign air bags so they inflate to lower pressures decreasing injury risk to smaller women and children. However, car manufacturers do not test safety devices for obese passengers.

In fact, a Harris Poll conducted in March of 2002 showed that 80 percent of people older than 25 are overweight based on the body mass index (BMI). However, crash tests normally use dummies that anthropometrically represent a “standard-sized” male weighing about 78 kg (172 lbs). Thus, some researchers suggest that safety testing authorities recognize that they are testing for only a small percentage of the population and utilize heavier and larger dummies in crash safety testing.

Others speculate that the higher death rate in obese people may be that car interiors are not be suitably designed for heavy people. Again, this is the responsibility of the manufacturer to determine the anthropometry of their user population. Some believe that obese people, with health problems such as high blood pressure or diabetes, could be finding it tougher to recover from injury. Still others think the link might be due to poor seat belt restraint during a crash. One researcher suggested that a large amount of fat tissue between the restraint system and the bony thorax introduces “slack” into the restraint system decreasing its performance.

For more information on the study see: Accident Analysis and Prevention (vol 34, p 221).

For more information and to calculate your body mass index (BMI) visit the Centers for Disease Control (CDC) website