An Air-Bag Wrinkle to Consider

In the SuperFreakonomics chapter on cheap and simple solutions, we wrote:

And seat belts, at about $25 a pop, are one of the most cost-effective lifesaving devices ever invented. In a given year, it costs roughly $500 million to put them in every U.S. vehicle, which yields a rough estimate of $30,000 for every life saved. How does this compare with a far more complex safety feature like air bags? At an annual U.S. price of more than $4 billion, air bags cost about $1.8 million per life saved.*

A reader named Rich Merrill writes in with an interesting comment:

In the early 70’s I was employed at Ford, doing bumpers and air-bag (safety car) testing.? There is another factor that may need to be considered to get an accurate picture of air-bag effectiveness. In order to work well, the occupants must be belted into place.? The air bag doesn’t keep people in place, it just cushions them when they are flailing around at the peak of the impact. And, of course, there are secondary impacts that occur after the air bag has deflated, so belts are?also important for that “post-bag” event.

So, if the current seat belt usage is about 80%, there are 20% of the people riding around with less than optimal air-bag protection.? I’m not sure how you’d measure it, but this would raise the air bag statistics a bit.

Something you might want to put in future editions?

Note: I’m not a big air bag fan and I have no dog in this fight.? I’m a retired engineer (5 years) and left the auto business in 1975.? I agree completely with your comparative “dollars-per-life” analysis.? Simple solutions are just plain hard to “sell.”? Maybe because nobody is making a profit on them? (Pat-downs vs. $canners at airports?)

*See Levitt and Porter, “Sample Selection in the Estimation of Air Bag and Seat Belt Effectiveness,” The Review of Economics and Statistics 83, no. 4 (November 2001).


Well, if it's more complex and mandated by the government, it has to be better, right? Right?

Drill-Baby-Drill drill Team

I have a million dollar idea for safety: An exploding foam grenade.

A portable canister placed centrally in a compartment that automatically deploys with rapid deceleration. On triggering it fills the passenger compartment with quick-expanding rapidly-hardening foam. You unpack the passengers like Christmas fruit from Harry and David. It can travel with you and be easily redeployed or retrofitted to any old vehicle.

David L

Unless you think there is a way to cost-effectively get those last 20% of drivers to wear their seatbelts, this information does not change the economic analysis. The cost per life saved under "ideal" circumstances (i.e., everyone buckles up; everyone stops at red lights; nobody texts while driving) have no bearing on reality.

Another thing to consider: when it comes to airbags and seatbelts, the net cost per life saved is probably higher: there are a number of studies (including, I believe, at least one referenced in this blog) showing evidence that seatbelts and airbags decrease fatalities but increase risky driving behavior.


Does this analysis take into account health care costs for reduced injuries when airbags deploy in non-fatal accidents?

Eric M. Jones

I've read the Levitt and Porter paper. I don't see where the $4 billion figure comes from, and --let me take a wild guess-- the figure is wrong.

Dollar values of this sort need a paper by themselves to support them.

Regarding crash injuries. I was in a crash where the airbag probably helped. But I wasn't transported to a Level 1 Trauma Center. So how do you collect the data if nobody dies?

Seatbelts are correlated with a higher risk of lower leg injury in a crash, because nobody would look at your lower legs if you were dead because your head was smashed.

Me? I wanna to be thrown clear...


@drill-baby-drill drill team

Some hollywood types beat you to this idea by almost 20 years. Just such a feature can be seen in the movie Demolition Man circa 1993.


Air bags are intended to save vehicular occupants who aren't wearing seat belts, and are thus an atrociously expensive "idiot-proofing" feature of your current automobile. Having driven a Subaru into a tree, or rather having desperately tried, and failed, to direct said Subaru around the tree in question, I can tell you that air bags deploy as advertised. Being an EMT who has seen things none of you want to see, you can bet your life that I was wearing my seat belt. Amazingly, the car only suffered moderate damage, and the insurance company elected to repair it. The replacement of the air bag cost four times as much as my first car, a 1965 Beetle.


The data source cited is ten years old. I would question the accuracy of the cost numbers ("annual US price of more than $ 4 billion") for airbag systems and components for that reason.

The cost of technology in general has come down over the last ten years.

Mike B

Isn't the government calculated value of a life for Regulatory purposes something around 2 million dollars? Just saying that something costs 1.8 million per life saved doesn't allow a comparison unless you state the value of a human life. Last I recall this value was in the neighborhood of 1.5 to 2 million dollars so therefore air bags are right in line with what our government believes is a justified regulatory expenditure.

Compared with the new advanced train protection technology mandated in a 2008 law that threatens to cost hundreds of millions of dollars per life saved airbags are a downright bargain. Perhaps you should look into that instead.


I've always wondered why auto insurance rates didn't go down when primary seat belt laws were enacted.

Funny how that worked...


wouldn't this actually raise the seat belt stats as air-bags alone aren't actually useful? I guess it depends on how you compute the lives saved by airbags, and which marginal you are going on.

Ted Benson

If my life, or that of any of my family or friends, is saved, it is well worth the cost.


Do airbags reduce injuries and deaths among seatbelt-wearers? I'd like to see the numbers.

I regard airbags as a protective measure for people too stupid to wear a seatbelt. As such, airbags might well be a net financial loss to society even if they were a dollar each - but no-one, anywhere, ever got funding for a study of the economic benefits of culling the stupid.

I would relish being contradicted on this point.


I have never experienced the pleasure of having an airbag deploy, but I did once flip my pickup truck over on its side while driving on an icy road. Fortunately I had my safety belt on and was completely uninjured. A couple of passing motorists helped me push the vehicle back over. The impact had caused one tire to lose pressure, and there was a large dent in right front panel, but after changing the tire, I was able to continue my journey . I doubt I could have done that if there had been an airbag.


The purpose of an airbag is not actually to save vehicular occupants, but rather lessen any impact on them during the crash. So much trial and error, as well as chemical engineering goes into it that I am able to believe the large sum it must cost to produce. Effective or not, I ask myself, can this airbag and seatbelt "save" you from a crash coming from your side? Side crashes are very common especially in highways, and therefore, I am very concerned. Sometimes, the airbags have malfunctions and don't open, how can the car companies prevent that? And finally, how effective are these security devices?
I often wonder, how much is an individual willing and able to pay for a sense of security.


-By actual observation, the severity and fataility rate goes up dramatically when passenger/drivers are "thrown clear".

-By actual observation, seatbelt and airbag deployment together prevent many injuries and deaths from occurring.

-By actual observation widows/widowers/orphans and surviving family members of the disabled, along with the disabled themselves, face horrible burdens, emotional AND economic.

Once again the economists prove conclusively to know the cost of everything and the value of nothing.

Plac Ebo

Steve Landsburg in his book "The Armchair Economist" talks of a suggestion by Armen Alchian to reduce the accident rate: "... Require every car to have a spear mounted on the steering wheel, ..."


I don't know where Nile and Harry get the idea that airbags are protective only to those who don't wear seatbelts. My understanding is that they enhance survival in major crashes regardless of seatbelt wearing, but can be more dangerous in minor crashes if you're not wearing a seatbelt.


There would hane been no need for airbags if seat belt use had not first been voluntary in the weird american belief that being a danger on road used by others is a part of freedom instead of licence.

Jacques René Giguere


To # 3
Yes there could be more risky driving behavior ( what we economist call an income ) but experimentally that effect is small.

Jacques René Giguere