The Effects of Alcohol on Driving
Every day, almost 30 people in the United States die in drunk-driving crashes — that’s one person every 50 minutes. These deaths have fallen by a third in the last three decades; however, drunk-driving crashes claim more than 10,000 lives per year. That’s about one-third of the 36,560 people killed in motor vehicle traffic crashes on U.S. roadways during 2018. (NHTSA)
An alcohol-impaired-driving fatality is defined as a fatality in a crash involving a driver or motorcycle rider (operator) with a blood alcohol concentration (BAC) of .08 grams per deciliter (g/dL) or greater.
Alcohol is a substance that reduces the function of the brain, impairing thinking, reasoning, and muscle coordination. All these abilities are essential to operating a vehicle safely.
The Effects of Alcohol on Driving
BAC is measured with a breathalyzer, a device that measures the amount of alcohol in a driver’s breath or by a blood test.
The Effects of Blood Alcohol Concentration
Below is a table describing BAC and typical effects of various BAC levels
| Blood Alcohol Concentration (BAC) in g/dL | Typical Effects | Predictable Effects on Driving |
| .02 | Some loss of judgment; relaxation, slight body warmth, altered mood | Decline in visual functions (rapid tracking of a moving target), decline in the ability to perform two tasks at the same time (divided attention) |
| .05 | Exaggerated behavior. May have a loss of small-muscle control (e.g., focusing your eyes), impaired judgment, usually good feeling, lowered alertness, release of inhibition | Reduced coordination, reduced ability to track moving objects, difficulty steering, reduced response to emergency driving situations |
| .08 | Muscle coordination becomes poor (e.g., balance, speech, vision, reaction time, and hearing), harder to detect danger; judgment, self- control, reasoning, and memory are impaired | Concentration, short-term memory loss, speed control, reduced information processing capability (e.g., signal detection, visual search), impaired perception |
| .10 | Clear deterioration of reaction time and control, slurred speech, poor coordination, and slowed thinking | Reduced ability to maintain lane position and brake appropriately |
| .15 | Far less muscle control than normal, vomiting may occur (unless this level is reached slowly or a person has developed a tolerance for alcohol), major loss of balance | Substantial impairment in vehicle control, attention to driving task, and in necessary visual and auditory information processing |
