The National Transportation Safety Board (NTSB) made a recommendation this week that states ban hands-free, as well as hand-held, cell phone use while driving.

The board doesn’t have the power to force states to impose the ban, but its recommendations carry significant weight and they’ve already started a national conversation on the subject.

PhoneGuard, a provider of safe driving mobile applications, offers features such as text block, custom auto-reply, override, speed control, speed violation alert and emergency calls. It responded to the NTSB’s proposal.

“We applaud the NTSB’s proposal,” said Keith St. Clair, chairman of PhoneGuard. “Phoneguard has been at the forefront of building corporate awareness of the growing problem of distracted driving. We are strongly in favor of responsible texting and believe our product suite is uniquely positioned to make a real difference in the epidemic which is currently sweeping our society.”

NTSB has been swamped with calls, emails and tweets from drivers both praising and condemning the action.

“There is a large body of evidence showing that talking on a phone, whether hand-held or hands-free, impairs driving and increases your risk of having a crash,” Anne McCartt, senior vice president for research at the Insurance Institute for Highway Safety, said.

Nine states, D.C. and the Virgin Islands prohibit all drivers from using handheld cell phones while driving. Except for Maryland, all laws are primary enforcement: an officer may cite a driver for using a handheld cell phone without any other traffic offense taking place.

No state bans all cell phone use (handheld and hands-free) for all drivers, but many prohibit all cell phone use by certain drivers, such as novice and school bus drivers.

Jim Hedlund, a safety consultant and former National Highway Traffic Safety Administration official, recently examined 300 cell phone studies for the Governors Highway Safety Association. He couldn’t recall a single study that showed drivers talking on a headset or hands-free phone were at any less risk of an accident than drivers with one hand on the wheel and a phone in the other.

The government of Sweden recently came to the same conclusion: “There is no evidence suggesting that hands-free mobile phone use is less risky than handheld use.”

A growing shift in focus from the roadway to a multitude of other tasks impairs the ability of modern drivers. Drivers have been known to text-message, talk on a cell phone, watch a movie, write a grocery list, nurse a baby or put in contact lenses behind the wheel.

Of 6,000 drivers surveyed by the highway administration, 40 percent said they don’t consider it unsafe for drivers to talk on a hands-free cell phone. Less than 12 percent said that about a hand-held phone.

Marcel Just, director of Carnegie Mellon University’s Center for Cognitive Brain Imaging, said, “When someone is speaking your native language, you can’t will yourself to not hear and process it. It just goes in.”

Accident investigators have seen cases of drivers talking on hands-free phones whose minds are so engrossed in their conversations that they ran into something plainly visible.

“There is a standard code for crash investigations called roughly ‘look, but didn’t see.’ In other words, I was looking in the right place, but I didn’t register what was there,” Hedlund said.

Lawmakers in Pennsylvania don’t think the total cell phone ban would pass in their state. State Rep. Ron Miller once drove behind a swerving vehicle on Interstate 83.

“I sped up to see why this guy was swerving,” Miller said. “He wasn’t on a cell phone. He was reading a newspaper. I’ve seen [drivers] eating a hamburger and drinking soda at the same time.”

“When you’re dealing with [driving issues] you can’t just focus on one thing being a distraction,” he said.