One of the fastest slapshots in hockey was clocked at 175 km/h, at the 2020 AHL All-Star Weekend. Good thing then, that hockey players wear pads and helmets to protect themselves from such projectiles. Now, can you imagine getting hit by something clocking in at nearly twice that speed? Believe it or not, most airbags explode – or “deploy”, if you prefer – at a velocity of up to 322 km/h.

Airbags are standard safety equipment in modern vehicles. They deploy in a split second to cushion your head and body in case of a collision. And they work as intended – provided you’re seated correctly. Putting your feet on the dashboard may be comfortable, but that won’t help an airbag protect your life – it may even endanger it.

Safety equipment can’t be dangerous, can it?

“Although airbags are part of the vehicle’s overall safety system, they deploy with significant force, and may be triggered even in a minor collision,” said Lee Alderson, Senior Issues Advisor at the Ontario Ministry of Transportation.

“Drivers and passengers who put their feet on the dashboard while the vehicle is in operation expose themselves to potentially very serious injuries, especially if the airbags should deploy,” said Alderson.

The Insurance Institute for Highway Safety (IIHS) puts it plainly: “Arms and legs should never be resting against an airbag because the forces of a deploying airbag and the hot gases exhausted by the airbag may cause injury.”

What’s the worst that can happen?

An airbag is literally a fabric sack wrapped around an explosive. If an airbag deploys and there is a leg resting on the dashboard, that leg may be propelled backwards towards its owner at an extremely high speed. The resulting injuries have been described as “traumatic” and “life-changing.”

Beyond the damage done to the leg and foot – dislocation, breakage, or amputation – there’s also everything else the leg is connected to – such as the pelvis and thereby the spine – and that it comes into contact with – the face, the jaw, the forehead, and so on.

And since an airbag is usually triggered by the vehicle’s collision with something else, that means the passenger’s body is also in motion. Maybe that leg doesn’t get pushed back, but is only deflected by the airbag and instead goes upwards through the windshield or even the roof.

Whichever way the passenger’s body is going, it’s not going in the way the engineers intended when they designed the vehicle and its safety systems. If you watch any IIHS crash test video, you’ll see that the movement of the crash test dummies is very carefully measured, and most vehicles are pretty precise in how and where the dummy connects with the vehicle interior and airbags.

Considering injuries can happen in a collision even if everyone is in place and properly seated, you can imagine the damage if a passenger is out of position, contorted unnaturally, and moving haphazardly.

Is there an alternative?

So, putting your feet on the dashboard is clearly a bad idea. What if you just recline the seat all the way down?

Not so fast. “Seats and seatbelts aren’t designed for people to be slouched down in a reclined position,” Alderson says. He also points out that airbags don’t replace seat belts – the two operate in tandem to keep passengers from serious injury. “[Airbags] are designed for the driver and passengers sitting upright, with their backs and feet in the proper place, and the seatbelt positioned low on the waist and across the shoulder.” The IIHS is even more specific, recommending that passengers sit in the centre of the seat with their feet on the floor.

Keeping feet out of mouths

Vehicles on the road today are safer than ever, engineered to survive a wide variety of possible worst-case scenarios. But they can’t account for all scenarios, including when your passenger decides to darken your dash with their soles.

Next time someone throws their feet up on the dashboard to be more comfortable, be sure to ask them if that short-term comfort is worth the risk. Yes, a foot or leg injury may heal in time, but amputation, paralysis, and death are more difficult to walk off.

If the threat of injury and possible death is too vague, maybe remind them that an airbag explodes from its compartment at a rate of 322 km/h and ask whether they want any part of their anatomy to be at the origin of that explosion.