Alcohol breath testing is an extremely used technique for determining the intoxication level in the body, which is mostly examined for the individuals who are drunk driving. After identifying the determined intoxication, blood alcohol level is considered as the important variable. This test is a tortuous test, but is deemed to be a good estimate of the blood alcohol concentration. As the assumption of the end-exhaled breath sample exactly reflects the alveolar air which is in equilibrium with the blood.

The procedure of alcohol breath testing is conducted in an organized manner:

?Initially, drivers are tested at the road side for the alcohol impairment with a alcohol detector. If the test results positive, evidential breath testing is again performed at the police station. If a police officer suspects a motorist, driving under the influence of alcohol, they are asked to take a breath test.

?The driver has to blow into a disposable mouthpiece for each test, which takes just a minute to record the result. These detectors offer the results in four categories: "zero," "pass," "warn," and "fail". If anyone fails the test is arrested and sent to police station to perform an evidential breath test.

?A sample of the ambient air is tested as a blank check, which is followed by a check sample of an air/ethanol standard.. The concentration of alcohol in the standard sample is 35 ?g/100 ml airs. Two samples of breath are then taken from the motorist and tested, each separated by a sample of air.

?If the results from the two actual samples differ by 15% or more of the least result, or 5 ?g, the high rated will be considered as an error message. In such cases the driver has to provide a sample of blood or urine for laboratory analysis. If the least reading is greater than 50 ?g/100 ml breath, the driver is prosecuted.

?The evidential breath testing detectors use either a fuel cell or an infrared cell. An infrared cell directs infrared energy through the sample and any unabsorbed energy at the other side is detected. The high concentration of ethanol, leads to absorb more infrared occurs.

?The accuracy of the result depends upon the sample of breath from the alveolar air. As the driver breathes out, the detector constantly examines the expired air using an infrared cell. As the expiration continues the concentration of ethanol is enhanced. When the level of ethanol stabilizes, the breath sample is analyzed.

?Sometimes these detectors record the "interfering substances." When this occurs the test is aborted and a blood sample is required.

?The maximum level of alcohol that may be accurately detected by evidential breath testers is 220 ?g/100 ml air. The entire procedure takes 10 to 15 minutes with the fuel cell based instrument, and up to 5 minutes with the purely infrared based ones.

The above information illustrates about the Alcohol Breath Testing, its procedure and how it is conducted