Measuring Blood Alcohol Content

The means of measuring for the presence of alcohol in a person’s metabolism is known as blood alcohol content, sometimes also referred to as blood alcohol concentration, frequently abbreviated BAC. This is measured in specific densities: a BAC of .5 means that half of one percent of your blood is pure alcohol. Many different states and countries use this measuring stick to determine the legal and medical ramifications of drinking. Some measure it by the volume of blood and others by the mass; a breathalyzer will measure the fraction of mass on a one to twenty-one hundred scale, meaning that alcohol content of blood is over two thousand times denser than the alcohol content of a persons’ breath.

The relationship between blood alcohol content and the intake of alcoholic beverages depends upon several factors. A two hundred pound man who has had five drinks (one drink equaling around half an ounce of alcohol) will register a BAC of around .1, while a one hundred twenty pound woman who has had five drinks will register a blood alcohol level of around .2. Gender, body composition, and contents of stomach all factor in to the metabolism of alcohol and its representation in a BAC.

When a person’s blood alcohol level reaches .01%, the result of one or two drinks, it will be difficult to tell if they are impaired, if they show any signs at all. Some inebriation tests, such as holding a single foot off the ground for minute, may suggest the presence of alcohol. At a higher level, around .03%, a person will feel more relaxed, talk more openly, and have difficulty concentrating. Past the .05% rate, it is extremely difficult for most persons to operate normally, talking loudly and slurring words, feeling less inclined to follow social protocol, and acting more harshly to stimuli. In most parts of the United States, operating a motor vehicle past a .08 BAC constitutes a criminal offense. At the .1% rate a person is visibly drunk and has difficulty walking in a straight line or expressing a complete sentence, even if they are far more vocal. Irrational mood swings are common at this rate. Beyond the .15% blood alcohol content rate, the body begins to shut down. A person may feel drowsy and be sluggish, cannot keep their attention on a single person or point, and will likely have memory loss. Past .2% it is extremely difficult for any type of functioning; unconsciousness and even death may result from this much drinking.