When drinking and driving, the human brain has to deal with a large variety of tasks and data input, the requirements of which can be changed in a permanent way. In order to safely drive, one must maintain attentiveness, make quick decisions based on ever-changing information from the environment, and execute specific – sometimes difficult – maneuvers based on these decisions. When a driver consumes alcohol he impairs a wide range of skills absolutely necessary for carrying out these maneuvers.

Here are some more drinking and driving facts.

In the human body, the alcohol proportion to blood is usually revealed as the blood alcohol concentration (BAC). When talking about traffic safety and its issues, BAC is showed as percentage of alcohol in deciliters of blood – for example, 0.20 percent represents 0.20 grams per deciliter. A 160-pound individual will have a BAC of approximately 0.04 percent just one hour after drinking two 12-ounce beers or two other standard drinks on an empty stomach.

In every state in the country, specific laws stipulate drinking and driving BAC limits. According to these laws, it is illegal to drive any type of vehicle while having a BAC over the specific limit. The BAC limit for drivers age 21 and older is now 0.08 for all states.

A driver’s ability to split his attention between two or more sources of visual information can be impaired by a BAC of 0.02 percent or lower. But, when a BAC of 0.05 percent or more has been reached, the impairment occurs in the psychomotor performance: the driver has slower eye movements, visual perception, reaction time, and information processing. The risk of a motor vehicle crash increases as a driver’s BAC increases and the more demanding the driving task, the greater the impairment caused by even low doses of alcohol.

One of the most important variables related to crash risk is, according to recent research, youthful age—teenagers. Young drivers are known to be inexperienced in driving. It is clear that when alcohol is added to the equation, the effects will only get worse. Young people have crash rates that are substantially higher than those of other groups, especially at low and moderate BAC’s.

Even when alcohol is not involved, lack of experience and immaturity (specific to teen drivers) remain the main causes of motor vehicle crashes among drivers ages 16 to 20.

Some studies have concluded that drivers in this age group have a greater risk than older drivers of being involved in a fatal crash even with a BAC of 0.00 percent. The fact is, their lack of driving experience renders them less likely than more experienced drivers to cope successfully with hazardous situations. And, combined with an inclination for risky driving behavior such as speeding—along with a tendency to underestimate dangerous consequences of such behaviors and to overestimate their driving skills—contributes to the high crash rate among young drivers.

See some drinking and driving myths