IIHS estimates that injury risk has been reduced by only a quarter of 1%.
An airbag can help to prevent injuries from a car accident. However, injuries can still be caused by any explosive device that is triggered close to an individual. These devices can also be dangerous, as demonstrated by the Takata recall. The Insurance Institute for Highwaz Safety examined knee airbags more closely than ever to determine if they were causing more harm than good.
Safety first
IIHS recently examined data from 400 front crash tests it had conducted as part of its vehicle rating program. According to the IIHS report, knee airbags did not have an effect on injuries in front impact collisions with moderate overlap drivers. However, in small overlap impacts, airbags did not cause an increase to injury to the lower legs. Although the reason for this isn’t clear, we believe that a high-velocity bag slamming into one’s legs could be responsible.
IIHS also examined real-world crash data in order to evaluate knee-airbag effectiveness. The IIHS collected information from 14 states and this data supports their internal testing. The analysis revealed a slight reduction in injury risk from knee airbags, specifically by half a percentage point. IIHS claims that the number isn’t statistically significant. This matches their findings regarding moderate overlap front impacts. However, the very slight decrease in overlap impacts is offset by a slight increase.
Safety is paramount
IIHS points out that knee bags can also affect legs and knees. Inflated knee airbags may be used to limit lower body movement in a crash. This can reduce the impact forces that are felt higher up in your chest. Curiously, IIHS states that while the risk of injury to the leg was higher for small overlap impacts, the head injury rate was slightly lower. Although we don’t know why, it is possible that the limited movement of the lower body may be a contributing factor.
It seems that knee airbags do not reduce injury risk. Why are they in cars? According to the report, knee airbags may have a greater effect on those who are not wearing seat belts. However, IIHS does not test on unbelted dummies and so cannot confirm this.