Alcohol is a drug that effects the central nervous system.
Impairment from alcohol poisoning was originally defined by blood alcohol levels. It was observed that most people showed measurable mental impairment at around 0.05% blood alcohol concentration (BAC). Above this level it has been found that motor functions deteriorate progressively with increased blood alcohol concentrations. For the average person, unconsciousness results by 0.4% BAC. Above 0.5% (BAC), basic body functions such as the breathing or the beating action of the heart can be depressed to the point that death can occur.
Blood was the medium originally used to measure alcohol concentrations in the human body. Blood tests offer the ability to accurately test the same sample several times, if the sample is maintained properly. The disadvantages with blood analysis is that the collection process requires trained medical personnel, the sample collection is invasive, the analysis requires precise procedures by trained lab technicians , the results are not immediately available and the overall process is costly.
In the 1930's the pioneers in the development of breath alcohol testing took advantage of the fact that alcohol was found in the deep lung breath in proportion the alcohol found in the blood. Breath testing instruments were manufactured to capture a sample of alveolar breath for analyses. Some of the early instruments were crude, but today breath analytical instruments have evolved into low cost, highly accurate, rapid analytical systems that simply and painlessly collect a sample and calculate a result. Although a trained operator is still required, the collection and analysis process is simple. Additionally, many jurisdictions have defined alcohol in terms of breath instead of blood so that an extrapolation to blood in order to determine impairment is no longer necessary.
Interesting Historical Note: The terms Breathalyzer ? and Breathalyser ? have become synonymous with breath alcohol testing equipment. Both are trademarked names not owned by Intoximeters, Inc. In fact the term Breathalyzer originated from an instrument invented by R.F. Borkenstein that utilized Chemical Oxidation and Photometry to determine alcohol concentration. The instrument was originally introduced in 1954 and was widely utilized for more than 20 years.