Frequently Asked Questions

Dispelling the common myths and misconceptions about breathalysers and the analysis of alcohol in the breath.

I know I have to wait twenty minutes after the subject’s last drink before running a breath test, to allow for any residual MOUTH ALCHOL to be eliminated; but can I accelerate this process by giving him or her some water to rinse their mouth out with?

NO! This can result in a wrongfully low breath alcohol reading. This is because it will line the mouth with alcohol-free water [instead of saliva, which has previously equilibrated alcohol-wise with the blood], as well as causing a lowering of the mouth temperature. Each of these factors will result in a loss of alcohol from the breath as the specimen is delivered by the subject to the instrument. It is also possible [as has happened] that the subject may later claim that the water they were given had been laced by the tester with something stronger, and resulted in a high breath alcohol reading! Where possible, never allow the subject to eat or drink ANYTHING prior to a breath test. But in situations where this cannot be avoided, always then allow a period of at least twenty minutes to elapse before proceeding with the breath test.

Is it true that the breathalyser test just measures the alcohol that is in a person’s stomach, from their last drink?

NO: when we inhale, oxygen passes from the incoming air into our blood, and carbon dioxide passes in the reverse direction. This gaseous exchange process occurs most efficiently deep down in the lungs, where the air is at its warmest and where there is the greatest contact between the blood and the breath. If alcohol is present in the blood – and because it is volatile – some of it will evaporate from the blood into the breath. The important thing is that, although only a small portion of the alcohol actually evaporates, the proportion that does so is known is known to be a 2,300th part. This means that the ratio between the breath and blood alcohol concentrations in the lungs is relatively constant, even between individuals. It is this alcohol that has evaporated from the blood that we are measuring during the breath test, because its concentration is strongly related to the blood alcohol level. So breath analysis has nothing to do with any alcohol that might still be in the stomach; it actually provides a reliable measurement of what is actually present in the circulating arterial blood.

Is there anything I can take that will remove the alcohol from my breath, so that I can cheat the breathalyser test?

There are many myths and legends about various devices and materials that are supposed to remove alcohol from your breath – such as chewing chlorophyll chewing gum or cat litter or sucking a lemon, a copper coin or an aluminium lollipop. But none of these work! You should also take care when even considering trying one of these tactics if required to take a breath test. Such an action – even though it doesn’t work, but you tried it in the belief that it might – could be regarded by the police and, later, the prosecuting authorities as an attempt to pervert the course of justice. The penalties for conviction of this offence are likely to be very serious indeed.

Does the breath test instrument tell me how much a person has had to drink?

NOT DIRECTLY, NO. The breath test instrument tells you exactly how much alcohol the subject has in their breath at the time of the test. This level will, of course, be governed to some considerable extent by what they have had to drink; but many other factors also play a part – such as the subject’s gender and body weight, what they have eaten and when, over what period they actually drank the alcohol, and how long ago they finished – plus their own personal alcohol metabolism rate.

Some electronic cigarettes contain alcohol. So can the use by the subject of such a product affect the result of that person’s subsequent breath analysis?

NO. The alcohol present in the fluid contained in an electronic cigarette is burned up in the smoking process, and so does not enter its user’s mouth. This means that there is no effect on a breath test or analysis caused by mouth alcohol: nor can there be any additive effect to the person’s already-present body alcohol loading, resulting from their prior consumption. So, in summary, the use of an electronic cigarette by a subject just prior to their breath testing or analysis will have no effect whatever on the instrument reading produced. This fact has been proven by way of relevant practical experimentation at Lion: all readings [infrared and fuel cell] were zero, even when the breath was sampled literally within seconds of smoking.

Will smoking affect the result of a breath test using a Lion instrument?

There are many different chemicals in tobacco smoke, and some of these could either damage the instrument and/or influence the breath alcohol reading to a very small extent. The general rule is to allow a period of at least TWO MINUTES since the subject last smoked before taking a sample of breath from them. This delay period is generally more than adequate as, in most cases, any significant traces of smoke are gone from their lungs in under 30 seconds. On no account ever allow raw tobacco smoke to enter the instrument. This could possibly damage the sensitive alcohol sensing system within it.

How specific are the Lion breath instruments to ALCOHOL in breath?

All lion alcolmeter ®  instruments use a fuel cell sensor for the actual analysis process.  This has a very high specificity to alcohol in breath.  In fact, there will generally be nothing else in the breath of a living human that could cause an apparent ‘alcohol’ reading on this equipment. Fuel cell based instruments are certainly unaffected by hydrocarbons such as petrol or by ketones, which may be present in the breath of a person such as a diabetic, or someone on a low-carbohydrate diet.  These sensors will, though, respond to other alcohols apart from ethanol – such as methanol or propanol – although it is highly unlikely that anyone would have any of these present in their breath to any degree, if at all.  Even if they did, they would still be impaired anyway! The infrared-based lion intoxilyzer ®  range of instruments is different.  These are designed to meet current national and international specifications [such as OIML R126], which effectively require them to be specific to ethanol.  This is achieved by multi-filtering infrared optical techniques in conjunction with the controlling analytical software.

Will medicines affect the breath alcohol reading in a Lion breathalyser instrument?

Alcohol is a volatile chemical. This means that it evaporates from the blood into the breath.  Any medicine taken in tablet form is plainly a solid, which cannot evaporate into the air, so it is not in the breath, so it cannot affect the alcohol reading. Any liquid medicine that contains alcohol will plainly cause some increase in the breath level. However, provided the user complies with the stated dose, then such an elevation will be both very small and quite temporary.  Also, the analytical technology used in Lion instruments be unaffected by practically all other liquid ingredients in the medicine. So, in general: NO, medicines cannot influence breath alcohol readings as obtained using Lion breathalyser instruments.

I have seen some very low cost breath instruments on sale on the internet, and in petrol stations: are they any good? How do they compare with Lion’s?

Unlike Lion instruments, which all use fuel cell analytical technology, these products almost invariably use semi-conductor sensors for the actual alcohol analysis.  Although low in cost, these semi-conductor sensors suffer from a number of technical limitations and, as such, are not used in the equipment that is used by any police force.