Air bags may encourage some drivers to become more reckless than drivers of vehicles without the safety devices, a study says.

The study of 206 Virginia crashes in 1993 concludes that drivers with air bags were disproportionately responsible for multicar accidents and placed their passengers at greater risk than did other drivers."What it suggests is that air bag drivers are driving in such a manner as to offset the effectiveness of the air bag," said one of the study's authors, George Hoffer, an economist at Virginia Commonwealth University. "They think technology will bail them out."

The study, based on data from the Department of Motor Vehicles, analyzed fatal accidents involving 1990-1993 model cars, 43 percent of which contain air bags.

In crashes involving an air bag-equipped car and one with no air bag, the driver of the car with the air bag was responsible 73 percent of the time, Hoffer said. Of 13 single-car accidents in which passengers but not the driver died, nine of the drivers had air bags.

Central to the study is the theory of "offsetting behavior," which suggests that people adapt to safety improvements by taking more chances. The theory was pioneered 20 years ago by University of Chicago professor Sam Peltzman.