The file on the tragedy of Jennifer Reichardt - given an 'accidental death' verdict by a coroner last week - is being examined by the Department of Transport. Reichardt, 47, from Merseyside, died last year when her Rover crashed into another car whose driver walked away almost unhurt. Her airbag had inflated.

The question all motorists will want the DoT's engineers to answer is this: are airbags safe? The circumstances surrounding Reichardt's death may be unique to a British Coroner's court, but more than 100 fatalities have been attributed to airbags in the US. And, last year, a UK mechanic was killed when he accidentally triggered the device's explosive mechanism.

Originally termed the 'Auto-ceptor safety pillow', the airbag concept was first explored in 1957 by Ford and was later developed in Michigan by Eaton Yale and Towne. In 1971, the device was displayed to the media in Britain - with disastrous results. One reporter described the test crash: ' ... the dummy driver pushed the bag up against the screen, which flew out; and the dummy hit his head on top of the screen aperture with such force that a human would undoubtedly have broken his neck'. Later it emerged that the bag had also fractured the seat's anchorage.

By now, though, the US had signalled its intent to make the airbag compulsory within two years. As a safety solution, it was born out of laziness. Most Americans were unwilling to put up with the 'hassle' of seat belts. UK reaction was sceptical. Ironically, given that Reichardt was driving a Rover 414, one of the device's chief opponents in 1971 was Peter Wilks, technical director of the then Rover Company.

'Lap and shoulder harnesses already in use are better in many ways,' he said.

Nevertheless, in the US, the 50-litre bag became the norm. Once airbags and seat belts were seen as complementary, European cars followed. A smaller, 30-litre bag became the EU standard.

Devices vary, but for an airbag to be triggered, a sensor must detect deceleration by more than around 4gs (roughly four times the weight of your car) for more than a set period. Sensing the 'crash', the sensor sends a pulse which activates an explosive charge. This unleashes a gas which fills the airbag in a few milliseconds. Modern systems go from detection to deflation in less time than it takes to blink.

The RAC says it will await Rover's findings on the Merseyside coroner's report before considering its position, but technical service engineer John Clayton urges drivers to follow precisely what the manufacturer says: 'Most makers recommend that the driver's head should be no closer than around 33 centimetres to the steering wheel. The head restraint is vital, too. It should be at a height which positions its centre directly in line with the back of the driver's head. Drivers tend to set them too low, which can result in severe whiplash after impact, or a broken neck.'

The Royal Society for the Prevention of Accidents (RoSPA) has more specific advice. 'Modern car design standards permit the steering wheel to move forward in an impact by up to six inches,' says road safety advisor David Rogers. 'The safe deployment zone for an airbag - the distance at which your head contacts with the airbag on impact - is at least 10 inches. If you're sitting just 10 inches from the wheel and it moves forward six inches, the airbag will deploy four inches from your face - far too close.'

He says drivers should sit at least 16 inches, or 41cm, from the wheel. Rogers also criticises car makers: 'I am sure that every car maker has data at hand which shows the deployment zone for their airbags. Why the hell don't they tell their dealers?'

Car companies in the UK say they are getting closer to introducing the 'smart' airbag. For Ford, Visteon Automotive Systems says it has a design which detects impact speed, stature of front seat occupants and whether they are wearing belts. Because each bag has two gas generators, the speed and degree of inflation can be varied. In a lower-speed impact, the bag will go off more gently. Nevertheless, RoSPA says the car industry has been 'playing with smart airbags for five years' and is dragging its feet.

Meanwhile, TVR, the UK's biggest British-owned car maker, continues to refuse to fit airbags to its sports cars. Managing director Peter Wheeler says he habitually disconnects the mechanism from any car his family drives. 'I am not prepared to fit something to TVR cars that could damage somebody. In the long run, I think it's more likely that airbags will be banned before they become statutory. If they were ever fitted as a government requirement, it will open the government up to litigation from airbag victims and their families.'

While he is reading the file on Reichardt's death, there is little doubt that the same thought will cross Prescott's mind.