Fell refers to passive sensors as an extension of a police officer's nose, held up to 10 inches from a suspected alcohol source. He says passive sensors are quick (alcohol level is displayed in seconds) and objective. While they are legal and constitutional, they are not preliminary breath tests or evidential tests. They can detect low levels of alcohol, down to 0.01 percent breath alcohol concentration.
Passive sensors, available since 1995, increase detection of DUI by about 50 percent at checkpoints and 10 percent on routine patrol, Fell says. Yet, he notes, only about 4,000 units have been sold in the past five years. At best, he says only 2,000 or fewer are in use, penetration is very low, .4 percent out of 500,000 traffic law enforcement officers.
If all traffic enforcement officers used passive sensors, he says up to 700,000 more drunk drivers could be detected and 400 to 800 more lives could be saved per year.
"The general deterrent effect of their widespread use could be substantial," he says.
Continuous monitoring for offenders
Continuous transdermal alcohol monitoring detects alcohol consumption not by breath testing but through transdermal alcohol testing. This science monitors "insensible perspiration," the constant, otherwise unnoticeable excretion of sweat through skin. Specifically, continuous transdermal monitoring measures ethanol, a by-product of alcohol consumption, in insensible perspiration. The monitor locks to the ankle of an offender and information is uploaded to a remote server.
Currently, there are remote monitoring programs in 36 states and more than 22,000 offenders have been monitored since 2003. Typically, continuous transdermal alcohol monitoring is used on repeat DUI offenders. Although less common, first-time DUI offender programs also use this monitoring to evaluate an alcohol problem and try to prevent a first-time offender from becoming a second- or third-time offender.
Potentially, if worn by all repeat offenders convicted of DUI — assuming continuous transdermal alcohol monitors effectively prevent offenders from drinking — 100 to 200 lives per year could be saved, Fell says.
The estimates of lives saved given by Fell are based on "best case" scenarios. Adding them, their sum is not 13,000. To realize a nation without drunk driving, more must be done.
Emerging in-vehicle technologies
New technologies are being developed that could one day be found in every vehicle. Among them is an alcohol detection device which uses transdermal technology not worn on the body, but instead located on the steering wheel.
Before a vehicle equipped with this technology will start, a driver will need to touch a steering wheel sensor, which measures the driver's alcohol level. If the alcohol level exceeds a preset limit, the vehicle will not start and results are recorded along with date and time. If the driver passes the test, testing also will be done periodically. If an unsafe alcohol level is detected while the vehicle is being driven, the vehicle's horn will sound and emergency flashers go off.
Commercial vehicles and vehicles driven by teens are expected to be the first to have the technology. Within about a year, this technology will be available as a retrofit or built-in device for all types of vehicle steering wheels, or it could be installed off the steering wheel in another location convenient for the driver, such as the door or dashboard.
Another technology being developed is touch-based alcohol testing that uses optical technology. Two types of optical technology include NIR (near infrared) spectroscopy and multispectral imaging to look beneath the fingerprint.
Touch-based alcohol testing is non-invasive (no biohazards associated with blood, breath, urine, saliva or sweat); rapid (done in 30 seconds or less — no waiting for mouth alcohol to clear); accurate (equivalent to evidentiary breath measurements); and only requires passive contact from the individual being tested.
In simplest terms, NIR spectroscopy is like a flashlight held against the palm of a hand. Light penetrates the tissue and the reflected light contains unique information about the tissue structure and chemistry. Alcohol has a unique optical signature different from all other chemicals, and the signature can be used to determine alcohol concentration levels.
NIR spectroscopy technology for corrections, workplace and transportation applications could be ready as soon as 2007 and later for evidence collection.