Even at the time of its establishment on 1 January 1889, the foundations for the Dräger company's success were already closely linked to the consumption of alcohol. Together with an associate, Heinrich Dräger founded a small shop-cum-workshop named "Dräger und Gerling“, which soon devoted its attention to carbonic acid pressure reduction valves for beer taps. Carbonic acid is used to expel the beer from the tap, and the valve was designed to bring the highly pressurized carbonic acid in a gas cylinder down to the pressure required in the beer barrel, allowing the beer to bubble gently out of the tap. Local pub landlords frequently came to the workshop to complain about "faulty" pressure reduction valves, claiming that the flow of beer from the tap would regularly peter out. In the workshop, however, the valves were found to have nothing wrong with them. Closer inspection revealed that the inside of the valve was being cooled down by the expanding carbon dioxide to such an extent that the carbonic acid was freezing inside the valve, thus blocking it. Once the valve had been removed and warmed up, however, the beer was able to flow freely again and the valve was fully functional. As a result of these findings, a reduction valve was designed in which sufficient warmth was supplied from the ambient air to the critical point, preventing the carbonic acid from freezing. The patented design of this invention, known as the "Lubeca valve“, soon proved to be superior to rival devices. For the first time, it was possible to tap the carbonic acid stored in compressed gas cylinders safely and without risk, on a continuous basis and at an even and controllable pressure, ensuring a constant supply of beer in pubs and restaurants. Soon after, in 1891, the company was therefore renamed "Lübecker Bierdruckapparate- und Armaturenfabrik Heinr. Dräger“ (Lübeck beer pressure apparatus and accessories factory Heinr. Dräger).
Over the following years, the company, which in 1902 was renamed Drägerwerk, began to broaden its focus to include other applications for compressed gas technology. For instance, among other things respiratory protective devices with a supply of compressed air were manufactured, as were protective masks which were used, for example, by miners. In these masks, toxic carbon monoxide was removed by means of catalytic oxidation (combustion) of the carbon monoxide, turning it into perfectly safe carbon dioxide. During development of filters, it was discovered that the oxidation of carbon monoxide generates considerable heat. This led to the idea that this heat could be measured as a way of determining the concentration of carbon monoxide . By the end of the 1920s, this development resulted in the first Dräger carbon monoxide measuring instruments. The principle of measurement used in these instruments is still widely used today, for example to measure the concentration of combustible gases for explosion protection in many Dräger instruments. Building on these early beginnings with the first instruments for the measurement of gas concentrations, Dräger has evolved to become one of the world's largest manufacturers of gas detection technology for professional applications, where concentrations of explosive and toxic gases, oxygen and indeed alcohol need to be measured.
Even long before the invention of motorized vehicles, the effects of alcohol on people's perception and performance led to serious accidents. This resulted in 1872 in the issue of the British Licensing Act, which states that it is an “offence to be drunk while in charge on any highway or other public place of any carriage, horse, cattle, or steam engine”. When motorization began, the number of road accidents involving drivers under the influence of alcohol rose. In a magazine published in 1904 , for example, 25 serious accidents involving automobiles are reported in which there were 23 fatalities and 14 serious casualties. 19 of the automobile drivers were under the influence of alcohol. As a result, the British Licensing Act extended its definition of an offence in 1925 to cover "any mechanically propelled vehicle“.
Road traffic accidents caused by excessive alcohol consumption very soon showed that it was necessary to eliminate the risk situations resulting from alcohol-impaired driving. One of the most important and efficient methods of combating alcohol on the roads are frequent traffic checks. For this purpose, breath alcohol measurement is a much quicker and simpler method than blood sampling and analysis. Initial fundamental research into the correlation between blood and breath alcohol concentrations was conducted as early as the end of the 1920s. In the work “Über die Ausscheidung des Alkohols mit der Expirationsluft” (On the expulsion of alcohol in exhaled air), Swedish scientists Liljestrand and Linde published the first simultaneously measured concentration curves for breath and blood alcohol in 1930. This paved the way for a quick and easy method of determining the extent to which a car driver was under the influence of alcohol by measuring the breath alcohol concentration. On the basis of this and other studies, the first breath alcohol measurement device, known as the "Drunkometer", was developed over the following years. This instrument used a wet chemical analysis procedure and was thus more reminiscent of a portable laboratory than an easy to use instrument.
Although it was possible to determine a driver's breath alcohol concentration using the methods which had been developed, the procedures were not particularly practicable and, more importantly, were more or less impossible to use on site. Following World War II, there was a pressing need to carry out more frequent road traffic checks to combat the sharp rise in alcohol-related traffic accidents due to increasing volumes of traffic. Consequently, when the "blow tube" developed by Dräger in 1953 was launched with its sampling bag to determine the breath alcohol concentration of road traffic users, the police immediately responded with great enthusiasm. This tube made it possible to conduct an objective on-site measurement which could be used to enforce further actions to secure evidence. The fact that the tubes were easy and safe to use made them well-known all over the world and popular among law enforcement officers and test subjects alike. The "Alcotest®" brand name, which was coined at the time and protected for Dräger, has now become synonymous worldwide with breath alcohol measurement. What prompted the development of this breath alcohol test is described in an anecdote. One morning after a party in Dräger's test tube department, the chemists all accused each other of smelling most strongly of alcohol. To put an end to the debate, an objective and accurate method of measurement was needed - and this was how the Alcotest test tube came about, based on the many years of Dräger experience in the development of methods to measure gas concentrations.
In the USA, Robert F. Borkenstein also presented his "Breathalyzer" in 1953: the first "easy to use" breath alcohol measurement instrument. This was a chemical laboratory instrument whose result was analysed electrically. The instrument was even recognized in the USA as a substitute for the blood sample, and continues to be used today - in somewhat modified form - in some states of the USA and Canada. In the 1980s, Dräger took over production and sale of the Breathalyzer from the original manufacturer Smith & Wesson, and the instrument continued to be manufactured by Dräger until just a few years ago.
Over the years, the requirements for accuracy, speed and test frequency, as well as effective and economical use, have increased considerably. Thanks to the huge advances in sensor technology, the chemical processes have been replaced by small, reliable sensors, making possible the development of reliable and easy to use breath alcohol measuring instruments. The first outcome of these developments was the launch in 1980 of an electronic handheld instrument which used a so-called semiconductor sensor (based on tin dioxide) to determine the breath alcohol concentration. The instrument, called the Alcotest 7310, was the first to display a measured value within several seconds to show the alcohol concentration. With its digital display of results, the instrument allowed easy, objective assessment, making it much easier to carry out - and boosting the acceptance of - alcohol checks. Because of the semiconductor sensor used in the Alcotest 7310, with the limited longterm stability typical of such sensors, the instruments had to be calibrated within four weeks at the latest.
In the area of sensor technologies, the development of electrochemical gas sensors in particular was dramatic in the 1980s, enabling a level of sensitivity, accuracy and, above all, long-term stability to be achieved which had previously been thought impossible. Within just a few years, electrochemical gas sensors completely replaced semiconductor gas sensors in most professional applications, for example the measurement of hazardous gases. This also resulted in a new generation of handheld detectors for breath alcohol instruments measurements. The first member of the Alcotest 7410 family, one of the most successful handheld instruments in the world to date, was launched by Dräger in 1988. It achieved its extraordinary measurement accuracy, reliability and its calibration interval of six months by using an electrochemical DrägerSensor. In its different designs (Alcotest 7410 Plus, Alcotest 7410 Plus RS, Alcotest 7410 Plus com, Alcotest 7410 med), the Alcotest 7410 family is still the international standard for professional breath alcohol testing by the police and in industry and hospitals. In 1996, the Alcotest 7410 Plus RS saw the dawn of the computer era in handheld instruments for breath alcohol measurement. Thanks to the RS-232 interface, the stored measurement results can be sent to a PC, where they can be analysed according to various criteria such as number of tests, measured concentrations or time of test. In the year 2001 the family was enlarged to include the Alcotest 7410 Plus com, which set new standards in handheld instruments. The instrument combines the sturdiness and measurement accuracy of all Alcotest 7410 devices with complete text on a graphic display. Information for the user and tested person is no longer given in coded form but in plain text, greatly facilitating user-guidance and intuitive device use and making the instrument extremely convenient to use and operate. Texts can be viewed in a huge number of different languages and alphabets, including for example Vietnamese and Chinese. Of course, development did not stop there. In 2003, for instance, an Alcotest measuring system has been presented which (the respective legal regulations permitting) will allow a handheld instrument to produce measurements which are admissible as evidence in courts.
As use of breath alcohol measurement became more widespread, many countries demanded improved measurement results to allow them to be used as evidence in courts and, as such, to be recognized as equivalent to a blood sample. This prompted the development of infrared optical DrägerSensors. The first trials with this technology were carried out back in 1978 with a prototype known as the Alcytron. This led in 1982 to the stationary Alcotest 7010 breath alcohol measuring instrument. The infrared optical DrägerSensor located in the handset used a light wavelength in the range of 3.4 micrometres . The disadvantages of the device, which was state-of-the-art at the time, were the size and weight of the handset containing the infrared optical sensor, the instrument's limited ability to distinguish alcohol from other substances possibly being exhaled by the tested person, and the high level of power consumption which meant that the instrument could only be used on a mains power supply.
In 1985, when the first generation of the Alcotest 7110 was introduced, the foundation stone was laid for a new family of stationary breath alcohol measuring instruments which were also suitable for mobile use. The integrated infrared optical Dräger- Sensor allowed residual alcohol in the mouth to be detected, and the light wavelength in the 9.5 micrometre range meant that highly selective determination of the breath alcohol concentration could be achieved. An integrated printer also allowed measurement results to be printed out immediately on site. The further development of the Alcotest 7110 over the course of several generations, offering among other things much more powerful electronics and software, peaked in the Alcotest 7110 Evidential which since 1998 has marked a milestone in breath alcohol measurement. The instrument, which can be used in mobile and stationary applications, boasts a dual sensor system (infrared optical and electrochemical), breath temperature measurement, integrated printer, and pressure and volume sensors - its measurement results meet the strictest requirements worldwide and have set the standard in many countries. In Germany, the Road Traffic Act and a judgement by the Federal Supreme Court have deemed the instrument's measurements equivalent in court to the results of a blood sample.
Frequent police checks are an important and efficient method of reducing the number of road accidents caused by excessive alcohol consumption. A further step is only to allow a vehicle to be started once a breath sample has been submitted. This is where alcohol ignition interlock devices, so-called alcohol interlocks, come in. Once installed in a vehicle, the engine can only be started if a breath sample containing no alcohol is given. Nowadays, such instruments are in widespread use, mainly in North America. Dräger has applied its many years of experience in the development and production of breath alcohol measuring instruments to this area, too, resulting in 1995 in the launch of the first Dräger Interlock. This device is the successful outcome of Dräger's investment of its decades of experience in this new area of application for breath alcohol measurement. 50 years of Alcotest In developing and launching Alcotest products, the Dräger company has returned to alcohol, to the beer tap, and therefore to the very roots of its more than 110-year history. In 2003 Dräger was celebrating 50 years of Alcotest products. The company boasts a 50-year history in the development, production and sale of products for breath alcohol measurement. Today, Dräger Alcotest instruments are in use in every conceivable design worldwide. What started with the Alcotest tube has now evolved to include computer-controlled measuring instruments which prevent external influence and tampering during determination of the breath alcohol concentration. As such, Dräger Alcotest instruments help improve safety on our roads. The technology has changed over the years, and the quality of the results and the ease of use have improved continuously - proud testimony to 50 years of the name Alcotest.
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Alcohol, loved by some and cursed by others, is appreciated by most people as a means of stimulation and relaxation. We all know that consumption of alcohol has a negative impact on our perception and impairs our performance. However, this change in state does not necessarily need to be unpleasant, and it is not without reason that alcohol plays an important "supporting role" in our social life. Alcohol stimulates, inspires, liberates and exhilarates. It removes inhibitions and makes establishing contact easier. Alcohol is missing at no celebration, at no reception, at no banquet. Alcohol is a firm fixture of our everyday life, and has been for many centuries. Over the centuries, however, the requirements placed upon us in our social lives have changed considerably. Today we live in a modern world in which speed and technology define our daily life. Alcohol can be pleasant and fun, but the consumption of alcohol also holds many dangers.
When a person's consciousness is clouded by alcohol, this exposes us to many risks. Nowadays, we often encounter situations which demand our concentration and swift reactions. Who can tell how much alcohol is in his or her blood after two glasses of wine? Only our conscience can help us decide how much "too much" is, yet it is precisely our conscience which becomes increasingly unable to function with each sip of alcohol. In Germany, for example, 70,000 road accidents involving people under the influence of alcohol are recorded each year. The proportion of people killed and seriously injured in these accidents is particularly high, and for more than 10,000 people in the European Union, and more than 15,000 people in the USA, the accident proves fatal. Every single accident which occurs due to excessive consumption of alcohol is one accident too many! Such accidents show us where the limits are, making it clear what the difference between moderate and excessive can mean. Our sense of responsibility towards ourselves and others decides how we answer the question "alcohol, yes or no?". We all have a duty to accept this responsibility to prevent risk situations and dangers from occurring in the first place. However, only accurate, unmistakable proof of alcohol can show where the limits are, and this accurate proof can be obtained only by means of technical apparatus.
After drinking, the alcohol, or to give it its more accurate chemical name, ethyl alcohol or ethanol, is taken up by the blood in the gastro-intestinal tract and transported, via the heart and the lung, to the arteries of the brain. From the heart the blood is circulated around the rest of the body, into the arteries of the arms for example. From there it is distributed throughout the tissue and, finally, flows back through the veins.
Once alcohol reaches the arteries of the brain, it affects our speed of reaction and, in sufficient quantities, instantly provokes unusual, alcohol-related (driving) behaviour. The extent to which the speed of reaction is affected determines whether a person can still safely drive a car or whether there is an increased risk of accident. To judge whether or not a person is fit to drive would require a method of directly measuring this reduction in reaction speed at the roadside, but this is too expensive to be a viable option. To obtain nevertheless a useable procedure, "auxiliary variables" are used which permit an indirect conclusion to be drawn about a person's speed of reaction: a sample of air from the lungs or a sample of venous blood from the inside of the elbow is taken and its alcohol concentration determined.
The alcohol concentration is measured using air from the lungs or venous blood. In accordance with Henry's law, diffusion processes, which are also what causes oxygen to be taken up in the lungs, achieve a balance between the alcohol concentration in the blood in the lungs and the alcohol concentration in the air in the lungs. The breath-alcohol measurement involves directly determining this concentration. From the heart, the blood is circulated around the rest of the body, into the arteries of the arms for example. From there the blood is distributed throughout the tissue and, finally, flows back through the veins. A sample of this venous blood is taken from the inside of the elbow and used to determine the blood alcohol concentration indirectly by means of a further multistage procedure.
When determining a person's breath-alcohol concentration, a distinction is made between a preliminary screening test and an evidential analysis. A screening test is used by the police officer at the roadside to help decide objectively whether, if a particular limit is exceeded, an evidential breath-alcohol analysis needs to be carried out afterwards or whether a blood sample will be taken. Alcohol screening tests are performed using Alcotest tubes, in which chemicals are discoloured by the alcohol in the breath, or using electronic hand-held instruments. The familiar Alcotest tube with the sample bag is probably the oldest method of obtaining proof of alcohol in a screening test. However, requirements with regard to accuracy, speed, test frequency and effec- tive and economic use rose considerably over the years. A screening test must be able to be performed swiftly and supply accurate results, and today mainly electronic devices are used.
After a positive screening test an evidential alcohol analysis must be performed. Lawmakers in different countries have set appropriate limit values for the two procedures, i.e. breath and blood alcohol analysis. The breath-alcohol concentration (BrAC), a gas concentration, is expressed for example in milligrams of ethanol per litre exhaled air (mg/l). The blood alcohol concentration (BAC), a liquid concentration, is expressed in per mille (‰) and refers to the amount of ethanol in grams in each litre of blood. In many countries the lowest limit value which constitutes an offence is a blood alcohol concentration of 0.5 per mille (‰), the corresponding limit for breath-alcohol concentration being 0.25 milligrams per litre (mg/l) of exhaled air.
Even though the limit values for both procedures may be equivalent from a legal viewpoint, the breath-alcohol concentration nevertheless offers a more direct measure of actual impairment of driving ability. This is because of the path that alcohol takes through the body. From the place where the breath sample is taken from the lung, the blood transports the alcohol via the heart directly to the arteries of the brain, where the rapid increase in alcohol concentration impairs speed of reaction. Before the blood sample can be collected from the venous blood inside the elbow, however, the blood containing the alcohol is first distributed in tissue throughout the body. A further advantage of the breath-alcohol analysis is that the alcohol content can be determined directly and documented immediately, even on site, for instance at the roadside.
Modern breath-alcoholmeasuring instruments usually determine the breath-alcohol concentration using two different measuring systems: an infrared sensor or an electro- chemical sensor. Screening devices like the Dräger Alcotest 6510 use the electrochemical system of measurement. In evidential analysers like the Dräger Alcotest 7110, both systems are used at the same time. By using two measuring systems with different analytical specificity, the device is able to reliably detect any interfering substances which may be present in the exhaled air and which might influence the result in any way, such as petrol, paint or solvent vapours.
The sampling system in an electrochemical measuring system conveys a sample of air with an exact volume to the electrochemical sensor. The sensor selectively and highly accurately analyses the breath sample for the presence of ethanol. The sensor contains a membrane which is soaked in electrolyte and carries the measurement electrode and the counterelectrode. The electrolyte and the electrode material are chosen such that the alcohol to be analysed will be electrochemically oxidized on the catalyst layer of the measurement electrode. The electrons released by the reaction at the electrode cause a current to pass through the connection wires to the device's electronics. When the sensor current is analysed, the entire electrical charge released by the electrochemical reaction is determined, as this depends on the alcohol content in the sample chamber. This coulometric measurement method gives the sensor its particular long-term stability. The electrochemical sensor only reacts with this high level of specificity to alcohol. This means that acetone, for instance, which is sometimes to be found in the air exhaled by diabetics or persons on a starvation diet, cannot distort the measurement result, as ketones do not react at the electrodes. This prevents any false-positive measurement results.
In an infrared optical sensor, a light source emits light at different wavelengths (colours) in the infrared range of the spectrum (i.e. not visible to the human eye). In the schematic diagram, the colours of visible light are used rather than the invisible infrared spectrum. The light passes through two windows and an interference filter which only allows penetration of certain wavelengths (the green light in the diagram). A detector measures the intensity of the incoming light and transmits a corresponding signal to the device's electronics system. If a gas (ethanol, for example) which absorbs part of the light at a particular wavelength (the green light in the diagram) is present between the two windows, the light intensity measured by the detector will drop, as will its electrical output signal. The higher the alcohol concentration, the more the signal will be reduced, which is thus a measure for the alcohol concentration.
The alcohol concentration in the exhaled air (BrAC) increases as the body temperature and exhalation air temperature rise, due to the fact that an increased body temperature causes more alcohol in the lungs to evaporate out of the arterial blood in the lungs into the lung air. This takes place in accordance with a fixed physical principle known as Henry's law. Furthermore, as the body temperature rises, the exhalation air in the upper airways loses less of its alcohol concentration. For this reason, some countries (Germany, for example) require measurement of the breath temperature when a sample of breath is given for evidential measurements. When calculating the measurement result, breath temperature sensors are used to always relate the breath-alcohol concentration to a fixed exhalation temperature of 34 °C, ensuring that persons with for example a higher than normal body temperature are not disadvantaged by a higher measurement result.
How the test subject breathes directly before giving the breath sample, and the ambient temperature, also have an influence on the measurement of the breath-alcohol concentration at the end of the exhalation. For instance, if the test subject hyperventilates (breathes excessively) or if ambient temperatures are low, the area of the mouth and throat and the windpipe are cooled to below normal levels. This causes the temperature of the exhaled air to fall and, consequently, the uncorrected breath-alcohol concentration is lower. Likewise, hypoventilation (shallow breathing) or high ambient temperatures can increase the temperature of the breath and thus result in a higher uncorrected breath-alcohol concentration. If on the other hand the actual measured breath temperature is used to correct the final result and relate it to an exhalation temperature of 34°C, the way the test subject breathes and the ambient temperature will not affect the result of the measurement.
If shortly before the breath-alcohol concentration is measured the test subject consumes a substance containing alcohol (liqueur-filled chocolates, for example, or a breath freshener containing alcohol), the exhaled air absorbs alcohol not only from the lungs, but also from these substances in the upper part of the mouth and throat. As a result, the alcohol concentration detected in the exhaled air will be higher than the concentration in the lung air. However, within a few minutes this effect is completely cancelled out as the remaining alcohol in the mouth is taken up by the saliva or absorbed into the body. Waiting for at least 10 minutes before the measurement is performed and, possibly, comparing the results of the two individual measurements at intervals of two to five minutes can exclude the possibility of residual alcohol in the mouth influencing the final result.
The various measuring systems now available to determine the breath-alcohol concentration have reached a very high level of technological advancement, guaranteeing reliability even under difficult conditions. Precision instruments allow the exact and unmistakable detection of alcohol, neutralizing risk situations and preventing danger.
Every year, more than a million people worldwide lose their driving licence as a result of driving under the influence of alcohol. In Germany, for example, there are 70,000 road accidents a year involving people who are alcohol-impaired. For more than 10,000 people in the European Union and more than 15,000 people in the USA, these alcohol-related accidents prove fatal. In view of the statistics regarding road traffic accidents and fatalities attributable to alcohol consumption, which remain worryingly high worldwide, attempts have been made in recent years to find ways to reduce the figures. In North America, for instance, large numbers of so-called alcohol interlocks (breath alcohol ignition interlock devices, BAIID) are used to prevent alcohol-impaired drivers from starting and driving their vehicles. In most US states, interlocks have been a legal requirement for offenders who have been prosecuted for driving under the influence of alcohol, and today some 70,000 interlocks from different manufacturers are in use. Some Canadian provinces have also chosen to use interlocks in drink-driving offender programmes, while Australia and a number of European countries - Sweden and Finland, for example - have already introduced such programmes or have plans to do so. The European Commission and the Council of the European Union are also looking into the question of how to raise safety standards on Europe's roads and, in particular, how to reduce the number of accidents caused by alcohol. The Council of the European Union, for instance, has decided to investigate the "scope for using devices which prevent the engine from starting if the maximum bloodalcohol level authorised at national level has been exceeded“. The worldwide experience of interlocks to date and recommendations for countries looking at introducing this system are described in considerable detail in a position paper published by the International Council on Alcohol, Drugs and Traffic Safety (ICADTS). Furthermore, the European Commission has ordered a feasibility study to be carried out to investigate the introduction of alcohol interlocks.
An interlock is a breath alcohol measuring instrument with vehicle immobilizer which can be easily installed in a motor vehicle. Before the vehicle can be started, a breath sample has to be given. Once the breath alcohol measurement has been performed, the interlock prevents alcohol impaired drivers from starting the engine. An interlock comprises two main components: the breath alcohol measuring instrument with the measuring system and with the display, which is situated inside the vehicle, and the central unit which is generally installed under the dashboard and allows or prevents current being supplied to the vehicle's starter system. When the ignition is switched on, the interlock requests a breath sample from the driver. The result of the breath alcohol concentration measurement determines whether the vehicle's starter is released and the engine can be started.
The Dräger Interlock XT was developed on the basis of Dräger's 50 years of experience in the area of breath alcohol concentration measurement. The device meets all worldwide interlock requirements, offers the greatest possible convenience for the user and is even tamper-proof - thus setting new standards for alcohol interlocks. Measuring the alcohol concentration A reliable interlock these days uses an electrochemical sensor to determine the breath alcohol concentration. The sampling system conveys a breath sample of a precisely defined volume to the electrochemical sensor similar to the one used in the screening devices and evidential instruments of the Alcotest family. The sensor determines the ethanol content of the breath sample selectively and with a high degree of accuracy. The sensor contains an electrolyte-soaked membrane which carries the measurement electrode and the counter-electrode. The electrolyte and the electrode material are chosen such that the alcohol to be analysed is oxidized electrochemically on the catalyst layer of the measurement electrode. The electrons released from the reaction at the electrode dissipate as current through the connecting wires to the instrument's electronics. When the sensor current is analysed the entire electric charge generated during the electrochemical reaction is determined. This coulometric measurement method gives the sensor its particular long-term stability. The electrochemical sensor only reacts with high specificity to alcohol. As a result, acetone, for example, which can be found in the breath of diabetics and those on starvation diets, cannot distort the measurement result because the ketone group does not react at the electrodes. This prevents any false-positive measurement results. During development of an interlock, particular attention must be paid to ensuring that the instrument will be ready for use quickly, as car drivers find long waits after switching on the ignition particularly annoying. At normal or high ambient temperatures, the Dräger Interlock XT is ready for use within just 10 seconds. To allow a quick and reliable measurement at low temperatures too, the sensor and parts of the sampling system are heated. And because the interlock even works perfectly at -40°C (during the Scandinavian winter, for example) and at 85°C (in blazing sunlight, for example), it was given the name "XT", for "eXtended Temperature".
Besides interlocks with electrochemical sensors like the Dräger Interlock, devices equipped with semiconductor sensors are also available. Essentially, the semiconductor sensors have two disadvantages. Because of their lack of selectivity, other substances such as cigarette smoke, exhaust gases, petrol or acetone can produce a measurement result and, possibly, cause the starter to be blocked. Indeed, it has already been pointed out in many papers that interlock devices fitted with semiconductor sensors are extremely susceptible to interference. The second disadvantage concerns the long-term stability of the sensors. Devices with semiconductor sensors tend to require monthly calibration, while devices with an electrochemical measurement system can easily be used for six months before needing to be calibrated. The lack of reliability of interlock devices with semiconductor sensors was one of the main reasons why use of the devices in the USA initially took a long time to become widespread, despite the necessary legal framework already being in place. The ICADTS report therefore expressly recommends the use of electrochemical sensors.
If any residual alcohol or other substances in the mouth cause the starting motor to be blocked, a repeat breath sample can be given after a few minutes. During this period the driver must not smoke, drink or eat anything. After this time, it is certain that any residual substances will have been completely removed from the mouth and throat, so the test result can no longer be affected.
In Europe, an interlock must be approved in accordance with the EC Directive on the suppression of radio interference in motor vehicles, which has been a condition for the installation of electrical devices in motor vehicles since 2002. In addition, as an independent "alcohol ignition interlock device", it also requires a "general type-approval" from the German Federal Bureau of Motor Vehicles and Drivers. Requirements and standards for interlock devices are to be found worldwide: there is a European Standard, the requirements of the National Highway Traffic Safety Administration (NHTSA) in the USA, the Alberta requirements in Canada - introduced on account of the Province's extreme climatic conditions - and the respective Australian standard.
To install the interlock, the voltage supply between the vehicle's ignition switch (position starter relay) and the starter relay is interrupted. This means that no voltage is supplied initially to the starter relay when the key is turned to the starter position, so no voltage is available to start the starter motor . The interlock is fitted into the interrupted lead with a relay that only releases the voltage supply to the starter system when a breath sample with a sufficiently low breath alcohol concentration has been given. This installation procedure ensures that an interlock can only ever intervene in the engine starting process but can never influence a running engine, i.e. while the vehicle is moving. This is an important argument for the operational safety of the interlock.
In the Dräger Interlock XT, authorized service centres can set a number of parameters using special software. The set values for the parameters, for example, can be defined by the authorities if the interlock is to be used in the area of driver licensing law. In its default setting, the instrument does not display the measured breath alcohol concentration, but states merely whether the measured concentration is above or below the set limit value. This is designed to prevent a driver from using the interlock to drink up to (but not exceed) the concentration limit. For several minutes after the engine has been switched off, the vehicle can be started again without the need for a repeat breath sample. This is in the interests of road safety, allowing the vehicle to be started again immediately if the engine stalls in a critical situation or after brief stops. To ensure that the driver remains under the legal limit even during longer journeys, interlocks can be set to request repeat breath samples at random intervals. Even if the breath sample is not successful, however, the running engine will not be stopped. Instead, the interlock's data log records that a breath sample has been refused or that the alcohol concentration measured was too high. This allows the data to be analysed subsequently and such incidents detected.
While the vehicle is in use, all relevant incidents are recorded in the interlock's data log. The data recorded are the date, time, submission of or refusal to submit a breath sample, measured alcohol concentration, engine starts and stops, electrical bypassing of the interlock and any other attempts to tamper with the device. If so desired, an authorized service centre, using special software, can download the data, compile a data record and then print it out. When the interlock is used in drinkdriving offender programmes, this record can be sent to the driver vehicle licensing authority or other supervisory body for analysis, allowing proper use of the vehicle fitted with the interlock to be monitored.
When interlocks are introduced in a particular country, it is not only the device itself and its technical specifications which are important: how the devices are to be installed and regularly calibrated also needs to be clarified. A sufficiently dense network of service stations is necessary to allow calibration and, possibly, parameter setting, to ensure that a driver can reach a service station in a reasonable period of time. The stored data may also be downloaded at the service station and, if necessary, passed on to the supervisory authority.
There are two distinct areas in which interlocks may be used: as a preventive measure or as ordered by a court as part of a drinkdriving offender programme. Installing an interlock as a preventive measure in transport vehicles such as hazardous goods transporters, lorries, coaches and taxis can reduce accident damage and downtime, improve the image of the transport company, and make customers feel safer. In private vehicles driven by persons with a possible or recognized alcohol problem, the voluntary installation of an interlock as a preventive measure can help the person to overcome their problem and can give considerable reassurance to partners or to parents, for example, whose children also drive a car. The second area in which interlocks are used is when a court or other authority orders an interlock to be installed in the vehicles of drivers who have a history of offences due to driving under the influence of alcohol. Discussions about this type of use have recently started in Europe, too, and in some European countries preparations are currently underway to change the laws accordingly - in Sweden and Finland this has already happened.
Any discussion regarding interlocks should also take into account some of the arguments against their use. These include the costs of an interlock and, more importantly, the scope for tampering with and circumventing an interlock. The costs of purchasing or renting and installing an interlock can initially be seen as an obstacle to deciding to use an interlock. This is without doubt a justified objection, especially in the case of people who are less well off. However, if we look at the costs of using an interlock, we soon realize that the sum is roughly equivalent to the cost of one or two glasses of schnapps per day. Indeed, if the interlock prompts a person who habitually drinks alcohol to reduce their consumption, it may even turn out to cost no extra. The use of tools to circumvent the interlock, e.g. a pump or filter, will be detected by the Dräger Interlock XT and the engine prevented from starting. Any attempt to start the vehicle without first having given an acceptable breath sample is also recognized as tampering and recorded in the data log. A commonly cited argument against interlocks is the possibility of a sober person providing a breath sample on behalf of a drunk driver. Because of the specific way the breath sample has to be delivered, however, this person would have first had to practice how to do this. What is more, at least one sober person would have to be in the vehicle throughout the journey to provide acceptable breath samples whenever the repeat tests are activated. Finally, it is extremely unlikely that a sober person would knowingly provide a breath sample to enable a drunk driver to drive a vehicle. The simplest way to get around using the interlock is to drive a different vehicle in which no interlock is installed. However, if a person has been ordered to use an interlock as a condition for being permitted to drive, this is exactly the same as driving a vehicle without a driving licence. Obviously, as this is always possible even if a person has been banned from driving completely, an interlock cannot prevent it from happening. Experience of interlocks, however, especially in the US, where interlocks have been used in large numbers for several years now, indicates that tampering is very rare and that it is given far more weight in theoretical discussions about interlocks than it actually happens in practice.
Today, state-of-the-art interlock devices like the Dräger Interlock XT are available: such devices are quickly ready for use even under extreme temperature conditions, prevent tampering and, thanks to the use of electrochemical sensors, offer long calibration intervals. Installing an alcohol interlock is a reliable means of avoiding accidents caused by alcohol, as it can immediately separate alcohol consumption from driving. What is more, the interlock can support long-term behavioural changes with relation to alcohol consumption, thereby making an important contribution to improving road safety.
Worldwide, around one million people dieevery year as a result of traffic accidents,and another ten million are injured. OnEurope's roads alone, more than 40,000people are killed every year and 1.7 millionare injured, some of them remaining disabled for the rest of their lives. The estimateddirect and indirect financial costs inEurope total more than 160 billion euros ayear.Because of the severity of the accidents itcauses, driving under the influence of alcoholand/or drugs is one of the biggest problemson our roads. However, road users underthe influence of "other intoxicating substances",i.e. illicit drugs or medication, arenot easily detected by routine roadsidepolice checks, and are therefore only reflectedin the accident statistics to a limitedextent. All the same, the number of registeredtraffic accidents involving a driverwho has been proven to be under the influenceof drugs or medication has risenconstantly during the course of recentyears. In Germany, for example, 1,457 accidentsinvolving personal injury and a driverunder the influence of "other intoxicatingsubstances" were registered in 2004, and51 accidents resulted in fatalities. In addition, 842 serious accidents involving damage toproperty were recorded. What is more,there is also thought to be a very high numberof unrecorded cases, as drug detectionis subject to a complex and sophisticatedclassification process. Research into thereal number of cases indicates that onlyone in at least 1,000 drivers under the influenceof drugs is caught. It is not aseasy to tell whether someone is under theinfluence of drugs as is the case with alcohol(e.g. from the typical smell of alcohol).
Laws relating to "medical and illegal drugson the roads" differ from country to country.Generally speaking, proof of a person's unfitnessto drive is required in all countriesto allow them to be prosecuted for drivingunder the influence of alcohol or "otherintoxicating substances" ("impairment law").In addition, some countries (such as Germany,Belgium, Sweden France and Finland)have adopted other laws which do not dependon proof of influence; mere toxicologicalevidence of an intoxicating substanceis sufficient to impose a legal penalty("zero tolerance"). In June 2003, the European Legal Databaseon Drugs (ELDD) published a comparativestudy of the legal situation relating to"Drugs and Driving" in 16 countries. It wasfound that although driving under the influenceof drugs constitutes an offence in allcountries, there are considerable differencesregarding the rights of the police to testdrivers, the substances consumed and theapplicable legal penalties.The legislative and executive situation in anumber of countries (in alphabetical order)is described below.
Under the Austrian Road Traffic Act (StVO)of 1960, "drivers impaired by narcoticdrugs“ who are not able to drive a vehiclesafely are not permitted to drive or start amotor vehicle. An official doctor determineswhether the driver is impaired, and in thecase of a positive test result arranges fora blood sample.In the case of impairment which is notobviously due to drugs, oral fluid-based screening test devices can be used underthe 21st amendment of the StVO. Theamendment came into force on 1 July 2005and states explicitly that no screening testsmay be performed where there is a clearsuspicion of drug influence; in such casesthe driver must be presented to an officialdoctor. If an oral fluid test shows a positiveresult, a medical examination is conductedwhose result will determine what happensnext.The Interior Minister determines by decreewhich oral fluid screening tests can beused. At the present time, various methodsare being investigated by a study commissionedby the Federal Transport Minister.
Laws which make driving under the influenceof drugs an offence have been inplace in Belgium for many years.In response to the results of the "BelgianToxicology and Trauma Study", whichfound evidence of drugs in 19 percent ofinjured drivers, the law in Belgium waschanged in March 1999. As a result, it isnow forbidden to drive a motor vehicle iftoxicological evidence of intoxicating substancescan be found in the driver's blood. Although an initial suspicion is needed, thelaw takes effect even without any concreteevidence of the influence. The followingsubstances and detection limits (in theblood plasma) are covered by the law:amphetamine (50 ng/ml), the designerdrugs MDMA, MDEA, MBDB (50 ng/mleach), THC (2 ng/ml), cocaine or benzoylecgonine(50 ng/ml), and free morphine(20 ng/ml).Roadside drug testing takes place in threestages:- observation of external signs whicharouse suspicion that the driver is underthe influence of one of the definedsubstances (standardized recognitionprocedure),- taking of a urine sample which is checkedusing a urine screening test for drugs,- medical examination and blood sample.The use of oral fluid as a screening testmaterial is currently being tested as partof the ROSITA-2 project. An internalsurvey of police officers indicates that oralfluid is given clear preference over urineas sample material.
Under the revised version of Chapter 23 ofthe Penal Code, any driver of a motor vehilce whose blood is found to contain "anactive narcotic substance or its metabolite"will be charged with drinking while intoxicated,except in such cases where thesubstances were prescribed by a doctor.If, however, it can be proven that a person'sfitness to drive is impaired, the driver willbe charged with drinking while intoxicatedregardless of whether the substance wasprescribed by a doctor or not.FranceIn 1999, an article was incorporated into theexisting legislation in France to demand asystematic search for drugs as the possiblecause of fatal road traffic accidents.Since it proved insufficient to restrict thesearch to fatal accidents, the law was extendedto generally include "driving underthe influence of substances or plants classedas narcotics“ (law no. 2003-7 of 3 Feb.2003). Now, if evidence of consciousnesschangingsubstances is found in the blood,this automatically constitutes an offencewhich will have legal consequences. Thereare no specified limits.According to the law, all drivers involved ina fatal road traffic accident must now betested, as must drivers involved in a roadtraffic accident involving personal damage where there are reasonable grounds tosuspect the consumption of drugs. Furthermore,facultative testing can be carried outfollowing general road traffic accidents orother offences.Drug screening tests can be used by medicallytrained personnel as an additional aid.A urine sample can only be taken in hospitals,emergency wards or the surgery of thedoctor asked to take the sample. By theend of 2005, the police should have beensupplied with the first oral fluid-based drugscreening tests. If a person tests positively,a medical examination and blood sampleare necessary.
Driving under the influence of alcohol and"other intoxicating substances" is treated asan offence in Germany and is punishableunder § 316 of the German Criminal Code,StGB, or under § 315c StGB ("endangeringroad traffic"). No specific endangering ofroad traffic or erratic driving is necessaryfor a punishment to be imposed in accordancewith § 316 StGB, though a person'sunfitness to drive must be proved. Sincetoo little data is available (as yet) regardingthe link between the concentrations of activesubstances and a person's ability to drive, no specified limits exist for the "otherintoxicating substances" which, if exceeded,would constitute evidence of a person'scomplete unfitness to drive - in contrast toalcohol, for which the limit is 1.1 ‰. As aresult, besides relevant analytical evidence,the driver must be found to exhibit behaviouraldisorders caused by drugs. Impairmentcan be determined on the basis ofvegetative symptoms (e.g. size and reactionof pupils), coordination problems (includingdifficulties with walking and other tests ofcoordination) or noticeable psychologicaleffects (e.g. a mental slowness or inabilityto concentrate, with thoughts wandering).Several such symptoms must be in evidenceto prove a person's unfitness to drive, althoughone single but very pronouncedsymptom can also suffice. A laboratoryreading alone, regardless of how high thedetected concentration(s) may be, is notenough to prove a person's unfitness todrive.The blood sample taken is examined for thepresence of "other intoxicating substances"and a toxicological report is compiled. If thisshows evidence of impairment, and a courtcomes to the same conclusion in view ofthe documented behavioural disorders, theoffender's driving licence will be withdrawn An application for a new licence cannot bemade until the driving ban has elapsed(usually 6 to 12 months).Under § 315c StGB, the punishment willbe more severe if a person who is unfit todrive due to the consumption of "otherintoxicating substances" has actually causeddanger to life, limb or property of significantvalue.
The lack of specified thresholds to describetotal unfitness to drive makes it relativelydifficult to successfully prosecute drugdrivingin practice.Sanctioning of driving under the influenceof drugs became considerably easierfollowing amendment of § 24a of the RoadTraffic Code, StVG, as of 1 August 1998,which serves as an important complementto the existing criminal laws. Under Subsection2, a person driving a motor vehicleon a public road under the influence of anintoxicating substance is now guilty of anadministrative offence. This is assumed tobe the case if analytical evidence of theactive substance or its decompositionproduct is found in the person's blood.The intoxicating substances to which thisprovision applies are not specified in thelaw, but are listed in a separate annex, which can be extended by executive orderto include further substances if currentscientific knowledge deems this necessaryfor the sake of road traffic safety and ifreliable toxicological evidence can beprovided.
The substances listed can only be detectedin the blood for a short period of time afterconsumption, so police officers need towatch for symptoms such as red eyes, slowpupil reactions etc. which are indicative ofrecent consumption. These initial observationscan then be corroborated using drugscreening tests. A blood sample is orderedand analysed for confirmation purposes in alaboratory. If the blood sample tests positivefor one of the substances listed in the annexto § 24a StVG, a driving ban of up to onemonth and a fine can be imposed.Since at the present time analytical evidencein the blood is the only thing that constitutesan offence, § 24a (2) StVG redresses theproblem of there being a lack of penaltiesfor instances of drug-driving without consequences- in other words, situations inwhich it is not possible to prove conclusivelythat a person is unfit to drive within themeaning of §§ 316/315c StGB. As such,the administrative regulation can be seen as a "catch-all element" which complementsthe criminal law regulations with correspondinglylower legal consequences. The introductionof analytical thresholds to ensuresome degree of correspondence betweenthe duration of effect and detection iscurrently under discussion.
Under Article 187 of law 285/1992 in Italy,it is "… prohibited to drive a vehicle in analtered physical or mental condition resultingfrom the use of narcotic or psychotropicsubstances“. If road traffic police officerssuspect a driver to be under the influence,they have the right under Article 12, Sections1 and 2 to accompany the person in questionto a mobile or fixed sanitary facility for thepurposes of conducting a screening test ortaking a blood sample.
According to Article 8 of the Dutch RoadTraffic Law, drivers are not permitted todrive a motor vehicle under the influence"of a substance whose use - either on itsown or in combination with another substance- they know or should reasonablyknow to be capable of impairing a person'sability to drive". No analytical limits arespecified by the law.Legal proof that the driver is under theinfluence of intoxicating substances otherthan alcohol must be provided by detectinga substance potentially able to influencedriving ability in the blood or urine, byproving intention, and by demonstrating alink between the detected substance andthe effect which was actually brought about.At the present time, the inclusion of specifiedlimit values for "other intoxicating substances"in the existing legislation is underdiscussion. This would require the use ofreliable screening test equipment, preferablybased on an oral fluid sample obtainedon site.
Police in Spain can conduct drug testing atany time, even without any initial suspicion.Like in the German laws, analytical evidenceof drugs in the driver's blood is enough toconstitute an administrative offence. Nospecific limits exist, as the "zero tolerance"principle applies.For a person to be guilty of an offence,Article 379 of the Spanish Criminal Coderequires evidence of influence.
On 1 July 1999, a new provision for drivingunder the influence "of other intoxicatingsubstances" was included in the SwedishRoad Traffic Offences Act. Drivers areprosecuted who are found to have toxicologicalevidence of narcotics and benzodiazepinesexceeding specified limits intheir blood.
As of 1 January 2005, a zero limit cameinto force for certain drugs in Switzerland.Under Article 2, Subsection 2 of the RoadTraffic Ordinance (VRV), a person isdeemed unfit to drive when certain substancesare found in their blood. Althoughthe police still cannot conduct drug testingwithout any reason - unlike with alcohol -a road user can be subjected to a drugscreening test if he or she is found to beimpaired due to the influence of narcoticsand/or pharmaceuticals. If the result of thetest is positive, a blood sample, a medicalexamination and a chemical toxicologicalanalysis are ordered.According to ASTRA, the Swiss FederalRoads Authority, a person is regarded asunfit to drive if there is evidence of at least1.5 ng/ml of THC in their whole blood or aconcentration of at least 15 ng/ml of cocaine,free morphine, amphetamine, methamphetamine,MDMA and/or MDEA in their wholeblood. There is no need to prove any effect.On the basis of the results of the examinations, sanctions are imposed under criminalor administrative law.
Under Section 3A/4 of the Road Traffic Actfrom 1988, a person is guilty of an offenceif he or she drives or attempts to drive amotor vehicle under the influence of "otherintoxicating substances".To provide a legal basis for how to recognizedrivers under the influence, the new “UKRailways and Transport Safety Act” from2003 gives an officer on site the authorityto order drug screening tests. The samplematerial is not explicitly stated.
