Inflation can save your life


CONSUMER DESK/Airbags: Airbags have been around since the early 1980s, after nearly 30 years of experimentation and research. Concerns bout their safety have given rise to today's "intelligent" airbag system, says Brian Byrne

It's not the kind of thing any of us want to experience. And, even if it does happen, it's quite likely we won't remember the actual event itself. An airbag inflating and then deflating again as we impact with it happens in around 1/25th of a second. In that short instant, it may well have saved your life.

With any safety system, there are always loud naysayers: we've all heard the people who knew someone who "would be dead if they'd been strapped in" in relation to seatbelts. The fact is, though, vastly more people are saved than are killed because of such systems.

In the decade or so during which the technology became commonly available, it is believed that some 7,000 lives were saved in the US by airbags. The current estimate of 500 lives being saved by the technology each year is expected to increase dramatically as cars without bags leave the system.

The airbag is perceived by many to be a 1990s technology and in terms of general availability this is so. However, some Chevrolets in the US were equipped with airbags in a public test fleet in the early 1970s. GM and Ford had been conducting research in the area since the 1950s, while Mercedes-Benz began serious development of such systems in 1966 and was the first European manufacturer to offer the option of an airbag, in 1981.

Airbag systems evolved more rapidly in the US because drivers there resolutely refused to comply with seatbelt-wearing advice and, later, laws. In Europe, which adopted seatbelt use to a much greater extent, airbags came rather later and have been of different design to those traditonally used in the US. The "SRS" you see on the dashboard and steering wheel centre means "supplementary restraint system", and the bags are designed to be used in conjunction with belt systems.

Still, though their success was being acknowledged, and progressive manufacturers were developing and providing side and "curtain" systems to enhance further occupant safety, it became apparent that there was an alarming incidence of death and injury from airbags, especially among smaller passengers and children. The peak year was 1997, with 52 confirmed airbag-related deaths in the US, 27 of them children not in car seats, and four of them children in car seats.

A combination of public education and technology development brought those figures down to nine adults and four unseated children in 2000, and last year there were no reported airbag-related deaths.

One problem was that short drivers were sitting too close to the airbag, which inflates explosively at some 200 mph in around 20 milliseconds. Children sitting up front were also receiving a disproportionate impact, particularly as ordinary seatbelts are not suitable for youngsters under seven. There were also instances of bags going off at very minor impact speeds and causing varying degrees of injuries.

Manufacturers responded by developing a "dual inflation rate" or "intelligent" airbag system which use sensors to detect the weight of the passenger sitting behind the wheel, and also the impact speed, and provides a less aggressive inflation for more minor thumps. Ironically, the test fleet of Chevy Impalas in 1973 actually included such a system, but when airbags came back into favour in 1988 this feature had disappeared.

Today, airbag systems have become very sophisticated, and pretty well all occupants have some significant degree of airbag protection in even mid-range cars. The latest Peugeot 307 SW leisure vehicle, for instance, has a "curtain" system that extends side-impact head protection right along three rows of seats.

WITH increased numbers of airbags, care also has to be taken that the correct ones inflate in particular kinds of crashes, and this writer has seen in a real accident how a serious roll-over did in fact only deploy the relevant curtain systems.

Some people worry about whether airbags will become dangerous as cars get older. The manufacturers say modern bags have a useful life of 15 years before they must be replaced. Given that a not-uncommon number of eight airbags could cost around €4,000 to replace, it is likely that a 15-year-old car simply won't be worth the cost when that time comes around.

In the meantime, if you have a potentially fatal accident and walk away without any more than a few small bruises, some contact burns and maybe black eyes, you'll probably consider any cost to have been worth it.