Obesity may increase the chances of survival in road crashes

February 10, 2010

(PhysOrg.com) -- Overweight men have a better chance of surviving a crash, but only if they're wearing a safety belt, according to the University of Michigan Transportation Research Institute.

In a new study in the current issue of the journal Traffic , UMTRI researchers Michael Sivak, Brandon Schoettle and Jonathan Rupp found that belted male drivers who are obese (those with a between 35 and 50) have a 22 percent lower probability of being killed if involved in a fatal crash than belted male drivers who are underweight (those with a BMI between 15 and 18.4).

However, the opposite is true for unbelted males, they say. The probability of being killed is 10 percent higher for unbelted male drivers with a BMI between 35 and 50, compared to those with a BMI between 15 and 18.4.

The UMTRI researchers analyzed data from the National Highway Traffic Safety Administration for nearly 300,000 drivers involved in fatal crashes in the United States from 1998 to 2008—about 51 percent of whom were killed. They found that, overall, drivers who fail to wear safety belts are 2.1 times as likely to die in a fatal crash as those who are belted.

Further, their results indicate that female drivers are 1.1 times as likely to dies as male drivers. However, for women who wear safety belts, a normal BMI leads to the lowest risk of death, while both higher and lower BMIs increase the risk.

Belted female drivers with a BMI between 35 and 50 have a 10 percent higher probability of being killed in a crash than those with a normal BMI between 18.5 and 24.9. Likewise, the probability of being killed is 8 percent higher for those with a BMI between 15 and 18.4, compared to those with a BMI between 18.5 and 24.9.

The researchers found no statistically significant differences among the BMI categories for unbelted women drivers.

"Our findings suggest that for increasing BMI, the optimal balance between the positive effects of extra cushioning and negative effects of extra mass and momentum depends on the gender of the driver and the use of safety belts," said Sivak, research professor and head of UMTRI's Human Factors Division.

"At a similar BMI, men are generally heavier than women because of height differences. Therefore, a man is more likely to overload the airbag, resulting in the increase in risk with increasing BMI for unbelted men. The decrease in risk with increasing BMI for belted men is likely because the safety belt tends to prevent this overloading."

Overall, Sivak and colleagues say their findings suggest that the designs of airbags, safety belts, knee restraints, seats and other components of occupant-restraint systems may need to be improved to better protect and their passengers at both extremes of BMI.

"Doing this will likely require new tools that can be used to evaluate the ability of restraint systems to mitigate injury potential, such as new crash-test dummies and finite-element models, because current dummies and models represent normal BMI occupants," Sivak said.

Related Stories

Recommended for you

Moderate coffee drinking 'more likely to benefit health than to harm it', say experts

November 22, 2017
Drinking coffee is "more likely to benefit health than to harm it" for a range of health outcomes, say researchers in The BMJ today.

When traveling on public transport, you may want to cover your ears

November 22, 2017
The noise levels commuters are exposed to while using public transport or while biking, could induce hearing loss if experienced repeatedly and over long periods of time, according to a study published in the open access ...

Different types of alcohol elicit different emotional responses

November 22, 2017
Different types of alcohol elicit different emotional responses, but spirits are most frequently associated with feelings of aggression, suggests research published in the online journal BMJ Open.

Air pollution linked to poorer quality sperm

November 22, 2017
Air pollution, particularly levels of fine particulate matter (PM2.5), is associated with poorer quality sperm, suggests research published online in Occupational & Environmental Medicine.

Sunrise and sunset guide daily activities of city-dwellers

November 21, 2017
Despite artificial lightning and social conventions, the dynamics of daylight still influence the daily activities of people living in modern, urban environments, according to new research published in PLOS Computational ...

Older men need more protein to maintain muscles

November 21, 2017
The amount of protein recommended by international guidelines is not sufficient to maintain muscle size and strength in older men, according to a new study.


Adjust slider to filter visible comments by rank

Display comments: newest first

not rated yet Feb 10, 2010
A possible factor may be seating position: Larger people tend to set their seat further back from controls, increasing the available crush-zone...

Of course, this only applies to the moderately obese. Beyond that, the available space may diminish again...
5 / 5 (1) Feb 11, 2010
I certainly hope no one spent alot of money to figure out people with extra padding do better in crashes where they're strapped in.
not rated yet Feb 11, 2010
Dude. They bounce.
not rated yet Mar 10, 2010
I agree with "froqz" I laughed when I saw this article headline.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.