(Lansing State Journal, November 27, 1996)
Every year more than 25,000 people in the United States are killed and over 500,000 are injured as a result of drunk driving accidents. To try and reduce this problem, the police have increased efforts to educate the public about the dangers of drinking and driving, as well as establish stronger penalties for those who are convicted of driving under the influence of alcohol (D.U.I).
One device that the police often use to test drivers who are suspected of being drunk is called a breathalyzer. A breathalyzer, which is small enough to be carried in a police car, is a type of spectrophotometer. A spectrophotometer is an instrument that measures the amount of light that passes through a sample.
The breathalyzer contains an orange chemical called dichromate. When a person blows into the breathalyzer any alcohol in their breath reacts with the orange dichromate, turning it green. When the dichromate turns green less light can get through the sample. The more alcohol in the suspect's breath the more green the dichromate will become. The breathalyzer uses the amount of light that passes through the sample to calculate the amount of alcohol in the person's breath. Currently the legal limit in Michigan is .01% blood alcohol content