Units of Breath and Blood Alcohol Concentration
Whenever we take a specimen of breath and measure its alcohol content, the most obvious [and most logical] method of expressing the result of that analysis is simply to define the weight of alcohol that is present in a certain volume of breath. And in fact, this is now how it is done in most countries. But there are several units of measurement in common use:
BREATH Alcohol Concentration Units
There are FOUR of these in use in various countries around the world:
Micrograms of alcohol per litre of breath
Usually abbreviated as – µg/L [or µg/l, or µg/1000ml, or µg/1000mL]
This unit of measurement is currently used in, for example, New Zealand, the Netherlands and Botswana.
A typical format for a measurement result expressed in this unit is 350, with the likely range being from 0 to 2,000.
Milligrams of alcohol per litre of breath
Usually abbreviated as – mg/L [or mg/l]
This unit of measurement is currently used in most of Europe, as well as in many other countries; such as South Africa, Taiwan and Japan.
A typical format for a measurement result expressed in this unit is 0.35, with the likely range being from 0.00 to 2.00.
Micrograms of alcohol per one hundred millilitres of breath
Usually abbreviated as – µg/100ml [or µg/100mL, or µg/%]
This unit of measurement is currently used in the United Kingdom, Ireland, Cyprus and Singapore.
A typical format for a measurement result expressed in this unit is 35, with the likely range being from 0 to 200.
Grams of alcohol per two hundred and ten litres of breath
Usually abbreviated as – g/210L [or g/210l]
This unit of measurement is currently used in the United States and Australia.
A typical format for a measurement result expressed in this unit is .080, with the likely range being from .000 to .600.
Converting from Breath to Blood Alcohol Units
In some countries it is still the practice to convert the result of a breath alcohol analysis to a blood alcohol concentration. In order to do this use must be made of a blood:breath ratio. There is much dispute and debate on this subject [much of which is now significantly out of date and misinformed], which means that different countries have each adopted their own assumed value of this ratio when preparing this legislation – such as 2,000:1 in France and Scandinavia; 2,100 in the USA, Australia and Korea; and 2,300:1 in the United Kingdom, Malaysia and Ireland.
There are also several units of blood alcohol measurement in use around the world:
BLOOD Alcohol Concentration Units
Milligrams of alcohol per one hundred millilitres of blood
Usually abbreviated as – mg/100ml [or mg/100mL, or mg/%]
This unit of measurement is currently used by the United Kingdom, Ireland, Cyprus, Singapore, Malaysia, Thailand, Canada, and by most countries in the Middle East.
A typical format for a measurement result expressed in this unit is 80, with the likely range being from 0 to 500.
Grams of alcohol per one litre of blood, Promille [w/v]
Usually abbreviated as – g/L [or ‰ w/v]
This system is used throughout much of French-speaking Europe, as well as in Spain and Portugal.
A typical format for a measurement result expressed in this unit is 0.80, with the likely range being from 0.00 to 6.00.
Grams of alcohol per one kilogram of blood, Promille [w/w]
Usually abbreviated as – g/Kg [or ‰ w/w]
This system is used throughout much of German-speaking Europe, and Scandinavia. When converting from this measurement unit to another it is necessary to make use of the specific gravity of whole blood, which is 1.06.
A typical format for a measurement result expressed in this unit is 0.80, with the likely range being from 0.00 to 6.00.
Grams of alcohol per one hundred millitres of blood]
Usually abbreviated as – % BAC [or % BAL, or g/100ml]
This system is used throughout the United States, Australia, South Africa and Korea.
A typical format for a measurement result expressed in this unit is .080, with the likely range being from .000 to .600.
Millimoles of alcohol per one litre of blood]
Usually abbreviated as – mmol [or m.mol/L, or mmol]
This system is used throughout much of the medical fraternity, most typically in pathology.
When converting from this measurement unit to another it is necessary to make use of the molecular weight of ethanol, which is 46.
A typical format for a measurement result expressed in this unit is 17.4, with the likely range being from 0.0 to 99.9.