As blood alcohol concentration increases so does impairment.
.020 - Light to moderate drinkers begin to feel some effects
.040 - Most people begin to feel relaxed
.060 - Judgment is somewhat impaired
.080 - Definite impairment of muscle coordination and driving skills. This is the legal intoxication level in Nevada.
.100 - Clear deterioration of reaction time and control. This is legally drunk in all states.
.120 - Vomiting usually occurs
.150 - Balance and movement are impaired. Here the equivalent of a 1/2 pint of whiskey is circulating in the blood stream.
.200 - Most people begin to experience blackouts
.300 - Many people lose consciousness
.400 - Most people lose consciousness and some die
.450 - Breathing stops. This is a fatal dose for most people.
Source: http://awareawakealive.org/educate/blood-alcohol-content