These breath-testers use a range of technologies including electrochemical fuel cells, infrared absorption, metallic oxide semiconductors and disposable color-change testers.

The disposable breath-testers are cheap to purchase and very useful in detecting alcohol in a person's system. When the test is positive, to check for other drugs in his system, the person is required to give a blood sample for confirmation by a laboratory. In addition his urine sample is also taken to test for the presence of other drugs in his system.

Breath testers have been in use in the United States since the 1940s. Then the machines used to detect alcohol were not as accurate as the ones used today. Nowadays mostly infrared absorption devices are used. They have a sample chamber from where the breath passes. This comes in contact with the infrared light, which counts the ions of alcohol thus measuring the alcohol level.

The Tennessee...
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