Passenger air bag deactivation switches are often misused, needlessly endangering children and depriving adults of life-saving protection, a US National Highway Traffic Safety Administration (NHTSA) survey has found.

"Airbags can be real lifesavers if used properly but pose grave risk to small children," said NHTSA administrator Jeffrey Runge. "We must redouble our education efforts to help consumers understand what constitutes proper use."

More than 12 million pickup trucks and a smaller number of passenger cars and cargo vans without rear seats are equipped with air bag on-off switches. Proper use of the switches requires drivers to turn the air bag off for children 12 and under but activate it when the passenger seat is occupied by an adult.

The NHTSA survey found that drivers with children in rear-facing child safety seats achieved the highest rate of correct use of the air bag switch - 86%.

But, on average, 48% of air bag switches were incorrectly left on for child passengers, aged 12 and under and air bag switches were incorrectly turned off for 17% of teenage and adult passengers.

On-off switches were first permitted in limited circumstances in May 1995 as an interim device pending the development of advanced air bag systems after a number of children and small adults were killed by bags activated by vehicle crashes.

The use of deactivation switches will be eliminated as advanced 'smart' air bag systems are put into vehicles. The phase-out will end by model year 2013.

The NHTSA surveyed the air bag switch status in 3,182 pickup trucks between July 1 and Nov. 22, 2000 at sites in California, Georgia, Michigan and Texas.