Roadside Breathalyser
This month marks the 50th anniversary of the first roadside use of the Breathalyser.
Express Medicals’ scientific adviser, Dr Simon Davis BSC PhD explores the history of this ground-breaking technology that’s trusted by the courts.
50 years of alcohol breathalysers – an occupational health revolution
The use of drugs in modern society is generally seen as socially unacceptable. Yet, one drug is openly used and readily available: alcohol.
Its effects are well-known, ranging from a relaxing soporific glow to violent and uncontrolled eruptions when consumed in excess.
The choice of whether, and how much alcohol, to drink could be seen as a personal choice. But when that behavior is embedded in a workplace, the use of alcohol can have fatal consequences. The depressive effects of alcohol impair both mental judgement and physical co-ordination. This has to be avoided at all costs when operating machinery, driving or undertaking any safety critical activity.
Where it all started
The effect of alcohol in the workplace has been a problem for many years. Some of the first UK drink driving regulations actually date back to 1872. The Licensing Act, made it an offence to be in charge of a carriage or horse whilst under the influence of alcohol. The first conviction followed shortly after, in September 1897 when George Smith was fined 25 shillings for being intoxicated while in charge of a horse-driven London taxi.
Such legislation was welcome, but the lack of any method to measure the amount of alcohol a person had consumed was a problem. Therefore, even though the law was applied, it was open to abuse and highly subjective.
Chemistry verses alcohol
Scientific knowledge around this period found that alcohol within the body was equally distributed through all fluid compartments. This meant that the amount of alcohol in the blood, urine and saliva would be proportionately equal to one another.
Alcohol testing in 1927
Armed with this knowledge, US doctor Dr Emil Bogen published a landmark study on the relationship between alcohol, blood and exhaled breath. The 1927 paper conclusively showed that although the amount of alcohol in breath was far lower than that of the blood, it was directly proportional. In other words, blood alcohol could be directly calculated from breath alcohol.
Dr Emil Bogen’s method
The method Bogen used to measure breath alcohol was a wonderful yet simple chemical process that could be easily copied. He placed a small amount of sulphuric acid and potassium dichromate into a football bladder. Then, the person being tested would breathe into the bladder and, if alcohol was present, the crystals would change color.
The degree and hue of color change provided an estimate of the amount of alcohol within the breath. This reaction worked exceptionally well but wasn’t practical for roadside or workplace testing.
The first “Drunkometer” in 1936
Due to the potential of Dr Bogen’s method it wasn’t long before the first usable breathalyser had been developed. The aptly named “Drunkometer” first went on sale in 1936 developed by Professor Rolla Neil Harger at the Indiana University School of Medicine.
The “Drunkometer” worked on a similar principle to Dr Bogen’s system. Breath was passed through an acidified solution of potassium permanganate. The presence and approximate concentration of alcohol was indicated by a change in color.
The first commercially available breathalyser known as the “Drunkometer” (Indiana 1936)
The first commercially available breathalyser known as the “Drunkometer” (Indiana 1936)
Although available to the UK market, the “Drunkometer” was never seriously adopted by the British police or regulatory authorities. The identification of inebriation was left to subjective sobriety tests.
Lab coats and legislation
Little changed until January 1966, when Parliament introduced the Road Safety Bill. Among other regulations, the first formal imposition of a maximum blood alcohol level was set: 80mg of alcohol in 100cc of blood. Concentration of alcohol above this level constituted an offence. This landmark legislation meant that, for the first time, intoxicated drivers could be identified and prosecuted with confidence and fairness. Things had come a long way since the 1897 conviction of George Smith.
The following year, Barbara Castle, then Minister for Transport, introduced the 1967 Road Safety Act that included approval of roadside portable breathalyzers. The effect of the Act combined with active enforcement by the police was almost instantaneous. It reduced road accidents by a full 10% in the following year.
Into The Modern Age
Alongside legislative changes, 1967 saw the development of the first electronic breathalysers. Tom Parry (UWIST) and electrical engineer Bill Ducie designed the prototype system in Cardiff. The two engineers went on to form Lion Laboratories and designed many of the workhorse devices commonly used over the past 50 years.
Modern day occupational health and police testing programs have a wide range of devices to choose from. Despite this, some providers still opt for ‘Colormetric’ detectors. These units use Bogen’s 1927 technique and depend on the operator observing the changes in color of potassium-dichromate crystals, hence the title Colormetric. These devices are cheap and have some functionality. They however, fall short of the precision and reliability needed to comply with modern day evidentiary standards.
Today
Currently one of the most accurate portable breathalyzer technologies is the Infrared or IR analyzer. These units work by passing a beam of IR light through a stream of breath gas. The IR is made up of many different wavelengths most of which pass freely through the breath. However, certain wavelengths of IR light are absorbed by alcohol.
The more alcohol present, the more IR light is absorbed. A small detector opposite an IR source quantifies the amount of absorbance as the light passes through the sample breath stream. This in turn is used to calculate the presence or absence and concentration of alcohol. This process is highly accurate, typically reporting breath alcohol concentrations to within 0.2g/l (200 ppm).
As IR systems have no moving parts they tend to be extremely stable requiring calibration only once a year or less. IR technology also results in highly specific systems that do not provide false readings. This results from the interference with other products.
A good example of this is the chemical acetone. This chemical can be produced within the body when someone is dieting. It has been shown in a number of studies that acetone produced in this manner can cause less specific breathalysers to report false positives. Although confirmatory testing normally identifies this error the subject will be exposed to significant unnecessary stress.
Can I fool a breathalyser?
Many myths circulate about how you can turn up roaring drunk for an alcohol test: then pop some gadget in your mouth and expel pure scented breath without a drop of alcohol present. This might have been the truth in some of the early devices, but a modern IR-based breathalyzer will reveal all your alcohol sins.
Popular myths include putting copper coins under your tongue, eating onions and drinking mouthwash. None of these will have the slighted effect – except mouthwash. Mouthwash is an exception as it will generally contain alcohol. Therefore, this would probably increase your reported alcohol levels significantly. Certain mouthwash products contain upwards of 30% alcohol.
Breathalysers have come a long way since their first inception as an acid-filled football bladder. They are now highly specific and accurate devices that can be reliably deployed at the workplace or on the roadside. Their results are consistent and dependable. Furthermore, they are regularly used as definitive evidence in civil and criminal court cases.
Without doubt, the not-so-humble breathalyser has prevented countless accidents and saved many lives.
Happy 50th anniversary!
Dr Simon Davis is a senior research scientist at Imperial College in the Faculty of Earth Science and Engineering
