Background: Breath testing today requires cooperation, significant physical effort, and is time-consuming. In order to reach an increased acceptance for general breath testing among drivers and professionals whose sobriety is of importance for a safe work environment, a less obtrusive breath testing procedure is desirable.

Aim: The aim has been to develop a breath alcohol analyser enabling fast, simple contact free breath testing with less physical effort. The sensor should meet the automotive industry’s requirements of long-time stability, and short start-up and response time, regardless of the ambient temperature. The long term goal is extensive implementation of an in-vehicle integrated unobtrusive alcohol detection system.

Results: The physiological rationale of the use of CO2 as a tracer gas has been investigated, and a new non-dispersive infrared gas senor enabling measurements of both breath alcohol and expired CO2 have been developed. The gas sensor has been evaluated with excellent results in sensitivity, cross-sensitivity. In a controlled drinking study a strong correlation (r=0.95) was found between reference tests and tests performed from a distance of a few centimetres with the new sensor. As proof-of-principle of unobtrusive breath testing we have now shown detection of normal human mouth and nose breathing, and artificial gas pulses containing alcohol from a distance over 60 cm in a vehicle compartment.

Future: To improve sampling of the driver’s breath, future work focuses on optimised signal acquisition and selection of positions within the vehicle compartment. Present challenges and important input to this work will be the influence from external air flows (ventilation), difference in breathing pattern (mouth/nose), passengers, and e.g. wind shield fluid. The sensor also provides possibilities to other applications, e.g. for access and passage control.

Objective: To review the effectiveness of current countermeasures in alcohol-impaired driving.

Method: This article provides an overview of the contributors to the alcohol-impaired driving problem in the United States and reviews the effectiveness of alcohol-impaired driving countermeasures.

Results: Many effective countermeasures have been used during the past few decades both to deter drivers from driving when they are over the legal limit for alcohol and to discourage driving while intoxicated (DWI) offenders from reoffending once they have been caught and convicted. In recent years, greater attention has been given to the problem of “hardcore” drinking drivers, a term coined to refer to those who repeatedly drive with high blood alcohol concentrations and are resistant to changing their behavior. Although such individuals are a legitimate target for attention, focusing predominantly on this group will result in missed opportunities to address a large portion of alcohol-impaired driving crashes. This article provides a review of the primary countermeasures that have been used to reduce alcohol-impaired driving and summarizes evidence for their effectiveness. It asks the question of where, in an environment of limited resources, attention should be focused.

Conclusions: General deterrent approaches, such as frequent and highly publicized sobriety checkpoints, have the greatest potential to save lives and should be the mainstay of state and local efforts. Specific deterrent approaches, aimed at deterring DWI offenders from reoffending, such as alcohol ignition interlocks, should be applied to all apprehended drivers, whatever their drinking history. Evidence suggests that they could benefit from them. In the future, advanced in-vehicle technologies that would prevent vehicles from being driven when their drivers are over the legal limit may hold the key to drastically reducing the alcohol-impaired driving problem.

Learn More >

Previous works investigated a spectroscopic technique that offered a promising alternative to blood and breath assays for determining in vivo alcohol concentration. Although these prior works measured the dorsal forearm, we report the results of a 26-subject clinical study designed to evaluate the spectroscopic technique at a finger measurement site through comparison to contemporaneous forearm spectroscopic, venous blood, and breath measurements. Through both Monte Carlo simulation and experimental data, it is shown that tissue optical probe design has a substantial impact on the effective path-length of photons through the skin and the signal-to-noise ratio of the spectroscopic measurements. Comparison of the breath, blood, and tissue assays demonstrated significant differences in alcohol concentration that are attributable to both assay accuracy and alcohol pharmacokinetics. Similar to past works, a first order kinetic model is used to estimate the fraction of concentration variance explained by alcohol pharmacokinetics (72.6-86.7%). A significant outcome of this work was significantly improved pharmacokinetic agreement with breath (arterial) alcohol of the finger measurement (mean k(Art-Fin) = 0.111 min(-1)) relative to the forearm measurement (mean k(Art-For) = 0.019 min(-1)) that is likely due to the increased blood perfusion of the finger.

Learn More >

The Driver Alcohol Detection System for Safety Program is a research partnership between the National Highway Traffic Safety Administration and the Automotive Coalition for Traffic Safety. The cooperative agreement seeks to assess the current state of detection technologies that are capable of measuring blood alcohol concentration, and to support the development and testing of prototypes and subsequent hardware that could be installed in vehicles. Three Phase I proof-of-principle prototype sensors now have been developed. Two of the sensors are designed to remotely measure alcohol concentration in drivers’ breath from the ambient air in the vehicle cabin, and the third is designed to measure alcohol in the drivers’ finger tissue through placement of a finger on the sensor. To validate the performance of the prototypes, unique standard calibration devices have been developed for both the breath- and touch-based systems that exceed current alcohol-testing specifications. A testing program was undertaken to provide an understanding of whether the devices ultimately can meet the performance specifications needed for non-invasive alcohol testing. Bench testing determined the prototypes’ accuracy, precision, and speed of measurement and established what additional development will be needed in Phase II. Limited human subject testing permitted an understanding of the in vivo relationship among the various measures of blood alcohol as provided by blood, breath, and the prototype devices. This paper provides the results of prototype testing and outlines further development needed.

Learn More >

Alcolocks and alcohol screening devices are becoming commonplace, and their use is expected to grow rapidly with cost reduction and improved usability. A new breath analyzer prototype is demonstrated, with the prospects of eliminating the mouthpiece, reducing expiration time and volume, improving long-term stability, and reducing life cycle cost. Simultaneous CO2 measurements compensate for the sample dilution and unsaturated expiration. Infrared transmission spectroscopy is used for both the alcohol and CO2 measurement, yet the entire system is contained within a small handheld unit. Experimental results are reported on the device sensitivity, linearity, resolution, and influence from varying measuring distance. The correlation between early and full-time sampling was established in 60 subjects. Basic concept verification was obtained, whereas resolution and selectivity still needs to be improved. Further improvements are expected by system optimization and integration.

Learn More >

State-of-the-art breath analysers require a prolonged expiration into a mouthpiece to obtain the accuracy required for evidential testing and screening of the alcohol concentration. This requirement is unsuitable for breath analysers used as alcolock owing to their frequent use and the fact that the majority of users are sober drivers; as well as for breath testing in uncooperative persons.

This thesis presents a method by which breath alcohol analysis can be improved, using carbon dioxide (CO2) as the tracer gas, offering quality control of the breath sample, enabling the mouthpiece to be eliminated, and bringing about a significant reduction in the time and effort required for a breath alcohol screening test. With simultaneous measurement of the ethanol and the CO2 concentrations in the expired breath, the end-expiratory breath alcohol concentration (BrAC) can be estimated from an early measurement, without risk of underestimation.

Comparison of CO2 and water as possible tracer gases has shown that the larger intra- and interindividual variations in the (end-expiratory) concentration is a drawback for CO2 whereas the advantages are a low risk of underestimation of the BrAC, and the limited influence from ambient conditions on the measured CO2 concentration. The latter is considered to be of importance because the applications likely imply that the breath tests will be conducted in an uncontrolled environment, e.g., in a vehicle or ambulance. In emergency care, the measurement of the expired CO2 concentration also provides the physicians with information about the patient’s respiratory function.

My hope and belief, is that with a more simple, reliable and, user-friendly test procedure, enabled with the simultaneous measurement of the CO2 in the breath sample, the screening for breath alcohol will increase. An increased number of breath alcohol analysers installed as alcolocks and more breath alcohol tests conducted in emergency care, is likely to save lives and diminish the number and severity of injuries.

Learn More >