A device to detect the presence and concentration of alcohol, using a colorimetric method in which the concentration of alcohol or its metabolic products in exhaled air causes differential color changes in a potassium chromate mixture. The concentration of alcohol in exhaled air correlates with blood alcohol concentration in a ratio of 2,100:1. The color change in breathalyzers is set to show when blood alcohol concentration exceeds the legal limit. In most of the United States and in many other countries, this is 0.08%. Advocates for stronger measures against alcohol-impaired driving seek reduction to 0.05%, which is the legal limit in some countries. The breathalyzer is widely used by police forces to detect alcohol-impaired drivers. Evidence from breathalyzer tests is admissible in most law courts. Refusal to take a breath test is commonly accepted as prima facie evidence of the driver's admission of alcohol impairment.
Subjects: Public Health and Epidemiology.