Blood Alcohol Concentration Limit when Driving

• Virtually all drivers are impaired at 0.05 g/dL BAC. Laboratory and test track research shows that most drivers, even those who frequently reach BACs of 0.15 g/dL or greater, are impaired at 0.05 g/dL BAC and higher regarding critical driving tasks. There are significant decrements in performance in areas such as braking, steering, lane changing, judgment, and divided attention at 0.05 g/dL BAC. Some studies report that decrements in driving performance in some of these tasks are as high as 30%-50% at 0.05 g/dL BAC compared to the same subjects at 0.00 g/dL BAC.
• The risk of being involved in a crash increases significantly at 0.05 g/dL BAC. The risk of a driver being involved in a crash increases at each positive BAC level (0.01, 0.02, 0.03, etc.). It rises very rapidly after a driver reaches or exceeds 0.05 g/dL BAC compared to drivers with no alcohol in their blood systems. Studies indicate that the relative risk of being killed in a single-vehicle crash for drivers with BACs of .05 to .079 g/dL is at least 7 times higher, and could be as much as 21 times higher, compared to drivers with a BAC of 0.00 g/dL.
• Lowering the BAC limit to 0.05 g/dL is a proven effective countermeasure. Alcohol-related traffic fatalities have been significantly reduced in several countries when the limit has been reduced to 0.05 g/dL BAC. While studies in European nations, Japan, and Australia each use a different methodology to evaluate these effects, the evidence is consistent and persuasive that crashes involving drinking drivers decrease at least 5% (and up to 18%) after a country lowers their illegal BAC limit from 0.08 g/dL to 0.05 g/dL BAC. A meta-analysis of international studies on lowering the BAC limit found a 5% decline in non-fatal alcohol-related crashes, a 9% decline in fatal alcohol-related crashes from lowering the BAC from 0.10 g/dL to 0.08 g/dL, and an 11% decline in fatal alcohol-related crashes from lowering the BAC to 0.05 g/dL or lower. In the United States, reducing the BAC limit from 0.08 g/dL to 0.05 g/dL in the State of Utah reduced the fatal crash rate 20% from 2016 to 2019, and the fatality rate was reduced 18%. In comparison, the rest of the United States showed reductions of just 6% in both fatal crash rate and fatality rate during that period.
• An upper BAC limit of 0.05 g/dL is a reasonable standard to set that has public support. A 0.05 g/dL BAC is not typically reached with a couple of beers after work or with a glass of wine or two with dinner. It takes at least four drinks for the average 170-pound (77 kg) male to exceed 0.05 g/dL BAC in two hours on an empty stomach and three drinks for the 137-pound (62 kg) female. The BAC level reached depends upon a person’s age, gender, weight, whether there is food in their stomach, and their metabolic rate. The National Highway Traffic Safety Administration (NHTSA) surveys in the United States show that most people would not drive after consuming two or three drinks in an hour (equivalent to 0.05 g/dL or lower) and believe the limit should be no higher than the BAC level associated with that. A 2016 survey indicated that 63% of drivers in the United States support lowering the illegal BAC from 0.08 g/dL to 0.05 g/dL. In 2019, Utah became the first state in the United States to lower its BAC limit to 0.05 g/dL, and other states have expressed interest in reducing their limit as well. The World Health Organization maintains a database of the BAC limits for every nation, and, as of 2018, over 100 countries around the world have a BAC limit of 0.05 g/dL or lower. Many of the world’s most populous nations are at or below this limit, including Philippines, Turkey, Germany, Thailand, and South Africa (all at 0.05 g/dL), Russia (0.04 g/dL), India and Japan (both at 0.03 g/dL), and China and Colombia (both at 0.02 g/dL). Over 20 countries, including the large nations of Pakistan, Brazil, Bangladesh, Iran, and Sudan have a total ban or “zero tolerance” for drinking and driving. However, there are still many nations, most notably the United States, that have national BAC limits of 0.08 g/dL.

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