National Transportation Safety Board Chairman Deborah Hersman said Tuesday she's adopting the policy because she wants her agency to follow the same safety practices it recommends for others.

Officials at the board said they were unaware of another federal agency with a similar policy.

Hersman told several hundred employees and guests at a ceremony at which she was sworn in as chairman that she was as hooked on her BlackBerry as the next person.

Nevertheless, she said the "risk of catastrophic consequences is too great" to use wireless devices while driving.

Hersman has been a member of the board for five years and was nominated for the chairmanship by President Barack Obama.

The NTSB's 400 employees will no longer be able to text or talk on cell phones while driving during work hours nor while driving during their off-hours if they're using a government-issued wireless device. The policy will apply to board members as well.

The board three years ago recommended that the Federal Motor Carrier Safety Administration prohibit cell phone use by motorcoach and school bus drivers. The motor carrier agency is still working on implementing the recommendation, according to NTSB's Web site. Officials for the motor carrier administration didn't return a phone call Tuesday seeking comment.

And in 2003, it recommended that states enact laws prohibiting drivers with learner's permits and intermediate licenses from using cell phones or other texting devices while driving. Nineteen states have adopted the prohibitions and six states and the District of Columbia have partial prohibitions.

There are no states that completely ban cell phone use by drivers.

Transportation Secretary Ray LaHood is scheduled to hold a summit on Sept. 30 of experts to figure out what to do about driver cell phone use and texting, practices that studies - and a growing number of accidents - show can be deadly.

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