Air bags are restraints designed to work in combination with safety belts. If all front seat occupants are properly positioned, with safety belts correctly in place, air bags should reduce the risk of head and upper body injury. But, there are calculated risks with the use of air bag systems. The force of deployment may cause abrasions, burns or, in some cases, serious or even fatal injuries.
Let’s examine the frontal crash air bag system. Most of these systems are comprised of an air bag module, crash sensors and a diagnostic unit. There are some frontal crash air bag systems that have an additional on/off switch.
The air bag module, located in the steering wheel and passenger side dashboard, contains an inflator unit and fabric air bag. To be effective, air bags must inflate very rapidly, generally at a speed over 100 mph. Due to this considerable force, the National Highway Traffic Safety Administration (NHTSA) recommends at least a 10 inch distance between the air bag module cover and the driver’s breastbone and passengers should adjust their seat as far back as possible.
Due to the force of the air bag deployment, children 12 and under should not ride in the front, nor should a rear facing infant restraint be used in the front seat. The rear facing infant restraint puts the baby’s head in close proximity to the air bag module, which could lead to serious head injuries or death if the air bag were to deploy and a child under 12 may be hit in the head with the air bag (rather than the chest).
The air bag crash sensors are located in the front of the vehicle. They measure deceleration and are activated by significant forces involved with frontal crashes or extreme avoidance maneuvers.
In a crash, the sensors send a signal to the inflator unit within the module. The igniter starts a reaction, which produces a gas to fill the air bag. As the bag fills, it dislodges the module cover and expands to full capacity in a fraction of a second. Deployment is usually accompanied with a cloud of dust combined with cornstarch or talcum powder, substances used to lubricate the air bag. After deployment, the air bag immediately starts to deflate as the gas escapes through the vented fabric.
The diagnostic unit is critical. It is activated when the vehicle ignition is engaged and monitors the functionality of the air bag system. If the diagnostic unit detects a problem, a warning light is activated. If the warning light comes on, the vehicle owner should get the unit inspected and fixed.
The additional on/off switch system allows vehicle operators to manually deactivate the air bag system. Deactivation may be necessary to accommodate a medical condition that places an occupant at specific risk, in cases where the driver cannot adjust their position to keep at least 10 inches from the steering wheel and when the owner cannot avoid situations that require a child 12 or under to ride in the front seat.
In a crash, air bags may reduce the severity of injuries and save lives, but they present a unique range of dangers as well. The dangers include:
• Acute respiratory distress from inhaling talcum powder at time of air bag deployment
• Abrasions or burns from air bag deployment
• Ear injuries, including tinnitus and benign paroxysmal positional vertigo (BPPV)
• Eye injuries, including anisocoria, hyphema and detached retina
• Head injuries if the occupant is not positioned correctly at the time of the crash
• Air bag deployment in a minor auto accident
• Failure to deploy in a serious motor vehicle accident
Yes, air bag systems have proven to be valuable, but almost too multi purpose. Fortunately, advanced technologies are being developed to tailor air bag deployment to the severity of the crash, the size and posture of the vehicle occupant, belt usage and how close that person is to the air bag module. The hope is to create a system that will use multi stage inflators so that the air bag is deployed at either a high force level, a less forceful level or not at all.