Starting at BACs of 0.05 percent, drivers show other types of impairment, including eye movement, glare resistance, visual perception, and reaction time. Other forms of transportation also have been investigated. Influence Alcohol-Induced Impairment Alcohol Tolerance. Based on miles driven, the highest driver fatality rates are found among the youngest and oldest drivers. Among male drivers younger than age 21, a BAC increase of 0.02 percent more than doubles the relative risk for a single-vehicle fatal crash.
Alcohol is less often a factor in crashes involving older drivers.
Alcohol consumption also increases the adverse effects of sleep deprivation. Recent Declines in Drinking and Driving Research shows that drinking and driving in the United States has decreased over the past decade, especially among young drivers. The proportion of all traffic fatalities that are alcohol related has decreased. The overall percentage of drivers with positive BACs among all drivers surveyed on weekend nights also has decreased. That Lower Limits to 0.08 percent.