The big risks of obesity and driving

JOANNE WILL

SPECIAL TO THE GLOBE AND MAIL

PUBLISHED OCTOBER 25, 2012UPDATED MAY 9, 2018

My dad is morbidly obese. We've been trying to get him to lose weight for years to improve his health, but it's come to the point where I'm afraid to be a passenger in his car or send my kids with him because I know he's at high risk of things like a heart attack or stroke. Am I being overcautious or do I have grounds to broach this with him? – Annetta in Orleans, Ont.

Population figures aside, it's no secret that our society is increasing in size. With this growth (in girth) comes a range of issues; some are related to health and others to safety.

The assumed average weight per passenger used by the U.S. Coast Guard in capacity calculations was increased this year – 25 pounds more than the figure used in the previous half century. Safety campaigners continue to call for heavier crash test dummies, while some airplane, bus, and even toilet seats are being adjusted.

So what does this have to do with driving a car, and your concerns for your dad? When examining the factors in fatal frontal crashes for post-2000 models, the U.S. Insurance Institute for Highway Safety and the National Highway Traffic Safety Administration found that more than half of the people who died were in exceedingly severe crashes or had physical conditions that may have raised their injury risk. Being elderly or obese were among the common factors.

"There are lots of medical issues that go with obesity. It's either increasing the risk of cardiac attack or illnesses like that which are more spontaneous, but also afflictions like diabetic neuropathy and sleep apnea that can affect your health and your driving skills," says Martin Lavalliere, co-author of a study, conducted by medical researchers at the University of Laval, that examined the association between obesity and motor vehicle crashes.

The study, Obesity, Where Is It Driving Us?, was published in the Journal of Transportation Safety and Security, and calls for obesity to be examined as a risk factor much the same as aging and distracted driving.

Lavalliere adds that there is more than the increased health risks to consider. Vehicles are designed around an "average" size passenger with a weight of 163 pounds, which many exceed. In some of the literature examined by the study, poor car-to-person fit is thought to be the leading cause of the increased risk of injury and fatality in car crashes for obese or overweight persons.

"There is what we call the anthro-mechanics. It's to do with the design of the car and how the person who is obese fits the car," says Lavalliere.

"One factor might be, if the seatbelt isn't long enough, the person is not going to wear it, which is an increased risk if ever they get involved in an accident.

"There's also a difference in the injury pattern that obese people sustain when they get involved in an accident. Because the seatbelt is holding them slightly differently, it might not apply restriction the same way on the hips and shoulders as it does for a normal weight individual," says Lavalliere.