According to the Insurance Institute for Highway Safety, the relative risk of fatality in a single vehicle crash for drivers with BAC levels between .05 and .09 are 11 times than for drivers with no alcohol in their system.
Numerous studies have shown that certain symptoms and characteristics tend to occur at every BAC level.
Individuals with a BAC of .02 percent tend to feel relaxed, experience slight body warmth, have a slightly impaired sense of judgment, and an altered mood that may result in a decline in visual functions and divided attention or the inability to perform two tasks simultaneously.
With a BAC of .05 percent, individuals usually show significant impairment in psychomotor performance. A person may experience slower eye movements, impaired judgment, and exaggerated behavior. Reaction time, steering, visual perception, and information processing are greatly affected, thus leading to reduced coordination.
Individuals with a BAC of .08 percent experience poor muscle coordination, particularly with speech, vision, hearing, balance, and reaction time. A person has a harder time detecting danger, and has impaired memory, self-control, reasoning, concentration, and judgment.
A BAC between .10 percent results in major impairment of both mental and physical control. A person will experience a clear decline in control and reaction time, such as the reduced ability to brake appropriately and properly maintain lane position. He or she may also exhibit slurred speech, slowed thinking, and poor coordination. Vomiting may occur.
With a BAC of .15 percent, an individual will experience significant decline in muscle control, disorientation, confusion, and a major loss in his or her sense of balance. There will be substantial impairment in terms of vehicle control, and attention to driving. Vomiting and blackouts may occur.
If an individual’s BAC is over .20 percent, .30 percent or even higher, then passing out is highly likely, and an individual will have little to no physical control. In certain situations, coma and death are also possible.
Source: Effects of Blood Alcohol Concentration (BAC), published