How long breathalyzers detect the alcohol

It is common knowledge that after a long night of drinking, activities like driving should be avoided. If the police want to review a potential driver with a blood alcohol level or if you want better judge of your own current state of intoxication, breathalyzers are useful tools for the detection and analysis of the amount of alcohol in your body.

Blood alcohol level

Alcohol is absorbed into the body at a much faster rate than food. On an empty stomach, 20 percent alcohol is immediately absorbed into the bloodstream. The body of the average person breaks down alcohol at a speed of 20 to 30 mg / ld. per hour. The standard rate of excretion alcohol is 0.015 points blood alcohol content (BAC) per hour. CAS breathalyzers are used to display the current measurement of alcohol in your body through breath analysis.


Alcohol is metabolized by the body or excreted through the breath, sweat or urine. Alcohol meters work by measuring the alcohol concentration in the air exhaled by a person. The alcohol concentration in the breath is around a ratio of 2100: 1 in relation to the concentration in the blood. Breathalyzers use any of the electrochemical fuel cell sensors, semiconductor oxide sensors or infrared spectrophotometers to identify breath alcohol content of a person in a reading and calculate as a percentage of blood alcohol content.

Types of breathalyzers

As mentioned above, there are three types of breathalyzers. Electrochemical sensors are accurate fuel cells, besides being conveniently portable. A fuel cell device measures the levels of alcohol through a chemical reaction which oxidizes the alcohol present and produces an electric current. More alcohol is equal to a higher current and readings are displayed accordingly. The infrared spectrophotometer used breathalyzers, moreover, are great devices that identify alcohol in the way the light is absorbed by the breath sample being examined. These are often found only in research centers or police stations, because of its size. The oxide semiconductor sensors are the latest development in the technology of alcohol. They use a sensor to measure the specific ethanol CAS and are growing in popularity due to the low cost, small size and extremely accurate readings.

The detection frame

The length of time that Breathalyzers can detect alcohol varies. For the most part, they can detect even the smallest amount of alcohol in the system of a person. However, concern for most people is that alcohol levels in the blood are below the legal limit to be considered drunk. In the US, the CAS of an individual must be under 0.04 to pass a breathalyzer test while 0.08 is considered intoxicated. As mentioned above, 0.015 of CAS is the standard amount of alcohol leaves the body. To determine the number of hours required for your body to free of alcohol, just do a breathalyzer test and divide it by the standard amount. For example, if a CAS breathalyzer gave a reading of 0.150, 0.150, divide it by the standard of 0.015, which is equal to 10. This means that it will take 10 hours for the alcohol to clean your body.


Since not directly measure the alcohol content in the blood, breathalyzers are prone to errors. Various factors such as body temperature, blood composition, the presence of blood in the mouth or acid reflux may play a role in creating inaccurate readings. Also, there are many compounds found in the body, such as ketones, which are chemically similar to alcohol, and high levels of such compounds can produce a falsely high reading. Devices using oxide semiconductor sensors have proven to be the most accurate, with accuracy levels of ± 0.01 percent to 0.10 percent CAS.