Take a deep breath. You may need it to start your car, if you’ve been convicted of driving under the influence and want to continue driving.

A new state law went into effect this month that permits people who have been arrested for DUI to apply for an ignition interlock device. If you get one, you can continue to drive legally.

Washington State Patrol Trooper Norm Larsen, who is based in Oak Harbor and covers the highways of Island County and parts of Skagit County, said it’s too early to say if the new law will have an effect locally.

“It’s a brand-new law,” he said. “It takes awhile to put it into place, and for citations to work their way through the courts.”

He said the devices have been around for at least five years, and that he runs into them occasionally during traffic stops.

“When we stop a person who has that restriction on their driver’s license, we have them turn off the engine and blow into the device to see if it’s hooked up and functioning correctly,” Larsen said.

“We run into them occasionally,” he continued. “You might find two in a week, then never see another one for three or four months.

“I’ve run into people who are required by the Department of Transportation to have one and don’t,” he added.

An alcohol ignition interlock device is like a breathalyzer installed in your car’s dashboard. Before the car can be started, the driver must breathe into it.

If a reading is higher than the programmed blood alcohol concentration, usually .02 percent to

.04 percent, your car won’t start.

At random times after the engine has started running, the device will require another breath sample, to prevent another person from doing the breathing for the driver.

If the additional breath samples aren’t provided, or they exceed the preset blood-alcohol level, the device will log the event, warn the driver and then start a racket.

Your lights may start flashing or your horn may start honking, and they won’t stop until the engine is turned off.

The device doesn’t turn off the engine if alcohol is detected while the vehicle is running; that could create an unsafe driving situation — and expose the makers of the device to a lot of liability, officials said.

Most ignition interlock devices use an ethanol-specific fuel cell for a sensor.

The alcohol undergoes a chemical oxidation reaction to generate an electric current. This current is then measured and converted to an alcohol-equivalent reading.

Although fuel-cell technology is not as accurate or reliable as the infrared spectroscopy technology used in breathalyzers, it is cheaper and tends to be more specific for alcohol, officials say.

The device keeps a record of activity and the vehicle’s electrical system. This log is printed out or downloaded each time the device’s sensors are calibrated by the vendor, commonly at 30, 60, or 90-day intervals.

Authorities may require periodic review of the log. If violations are detected, then additional sanctions can be implemented.

The devices aren’t new. Courts have required them on occasion for several years. Proponents hope the new law will make their use more number of convicted persons who continue to drive under the influence.

As of Jan. 1, people convicted of DUI who want to continue to drive legally, for example, someone who drives for a living, can apply to the state Department of Licensing for a $100 interlock license.

Proof of insurance is required.

You can’t get a device if you’ve been charged with vehicular homicide or assault, or if you’ve been convicted of those crimes in the past seven years.

If you were cited for driving under the influence of drugs other than alcohol, you aren’t eligible.

If you are granted an ignition interlock license, you must lease a device from one of several authorized vendors. A device costs about $75, plus a $20 monthly fee to the state.

Washington’s new law is similar to one in New Mexico, where statistics have shown a reduction in DUI deaths since the law was implemented.

Drunken driving remains the greatest cause of traffic fatalities in the state, although traffic fatalities are on the decline generally, the State Patrol said.

As of September 2008, there were 319 traffic fatalities, compared to 364 for the same period a year ago and 378 in 2006, the patrol reported.