It is surprising how few drinks can impair a driver’s judgment. A report from the National Transportation Safety Board estimates that alcohol-impaired driving contributes to thousands of deaths and tens of thousands of serious injuries each year. It is right to urge states to reduce that toll by lowering the allowable blood alcohol concentration for drivers from 0.08 percent to 0.05 percent.
All the states moved to the 0.08 standard after a federal law was passed in 2000 to withhold highway money from states that did not comply. Deaths from alcohol-impaired driving have declined from about 21,000 in 1982 to nearly 10,000 in 2011. But the current standard still allows impaired drivers to take to the road.
The new standard would not bar all alcohol, but would mean giving up a drink or two. A 180-pound man who might be able to drink four beers or glasses of wine in 90 minutes without reaching the 0.08 limit might have to cut back to three to meet the lower standard. A 130-pound woman who could have three drinks in 90 minutes and stay below the current standard might have two drinks instead.
Although most alcohol-impaired drivers in fatal crashes have blood alcohol well above 0.08, there is good reason to lower the standard.
Laboratory and driving simulator studies show that blood alcohol concentrations well below 0.08 and even below the proposed standard can diminish reaction time, vigilance, and the ability to stay in lane, while increasing drowsiness.
More than 100 countries have set limits at or below 0.05. It is time for the United States to join them.