The most recent "National Occupant Protection Use Survey (NOPUS)" on cell phone use for the first time reveals a decline in the number of drivers using cell phones behind the wheel.

The survey, sponsored by the National Highway Traffic Safety Administration, catalogues a decrease from 2006 to 2007 in handheld cell phone conversations from 6 percent to 5 percent, including a decrease in use by male drivers from 5 percent to 4 percent and in female drivers from 8 percent to 6 percent.

The use of cell phone headsets also decreased slightly from 2006 to 2007, from 0.7 percent to 0.6 percent, but the rate of handheld-device use increased slightly, from 0.2 percent to 0.4 percent. (The survey makes a distinction between handheld cell phone conversation, the most significant figure, and use of other handheld devices, such as text messaging or e-mailing.)

Young people are more likely to use cell phones while driving according to the study, with the age 16 to 24 demographic garnering the highest grade — 8 percent of drivers aged 16 to 24 are using cell phones at any given moment. Younger drivers are also more likely to use a phone headset while driving.

Most factors, such as race and road conditions, do not have appreciable effects on the rate of cell phone use of any kind. The only other notable split was the comparison of drivers carrying passengers to those driving alone. Drivers who are alone and drivers carrying passengers all under the age of 8 are much more likely to talk on a cell phone than drivers carrying older passengers, whether on a handheld or hands-free device. Drivers with no passengers had a 6 percent chance of driving while talking on a handheld cell phone, compared to a 1 percent chance for drivers with passengers all over the age of 8.

The disparity makes sense, since drivers who have someone to talk to in the car are less likely to seek conversation outside the car.

Cell phones akin to drunkeness

In 2006, University of Utah researchers published a study, "A Comparison of the Cell Phone Driver and the Drunk Driver," examining how profoundly a cell phone conversation might impair a driver’s concentration and performance. They found that cell phone use, whether with a handheld or hands-free device, impairs drivers similarly to being drunk to the legal limit.

According to the study, drivers talking on any kind of cell phone drove more slowly, were slower to hit the brakes and were more accident-prone at a similar rate to drivers whose blood alcohol content measured .08, the legal limit.

State laws

In response to the dangers of using a cell phone while driving, some states have passed laws restricting cell phone use, which may help explain the current decline in cell phone usage.

Currently California, Connecticut, Washington, D.C., New Jersey, New York, Utah and Washington have passed bans on hand-held cell phones while driving, while other states have elected to make the question a local option. Most states have not passed laws on cell phone use while driving.