WHEREAS critical driving performance is significantly impaired at blood alcohol concentrations (BACs) of 0.05 g/dL and above,
WHEREAS the risk of being involved in a crash increases significantly at BACs equal to or exceeding 0.05 g/dL,
WHEREAS lowering the illegal BAC limit for driving to 0.05 g/dL reduces alcohol-related crashes,
WHEREAS lowering the BAC limit to 0.05 g/dL has the potential to save lives if countries adopt it,
BE IT RESOLVED that the AAAM recommends that the United States and all countries with BAC limits above 0.05g/dL adopt a maximum BAC of 0.05 g/dL as the legal limit for driving.
Adopted: October 2009, updated October 2017
BLOOD ALCOHOL CONCENTRATION LIMIT FOR DRIVING: BACKGROUND INFORMATION
- Virtually all drivers are impaired with regard to driving performance at .05 BAC. Laboratory and test track research shows that the vast majority of drivers, even experienced drinkers who typically reach BACs of .15 or greater, are impaired at .05 BAC and higher with regard to critical driving tasks. There are significant decrements in performance in areas such as braking, steering, lane changing, judgment and divided attention at .05 BAC. Some studies report that performance decrements in some of these tasks are as high as 30%-50% at .05 BAC (Ferrara et al., 1994; Howat et al., 1991; Moskowitz et al., 2000; Moskowitz & Fiorentino, 2000).
- The risk of being involved in a crash increases significantly at .05 BAC. The risk of being involved in a crash increases at each positive BAC level, but rises very rapidly after a driver reaches or exceeds .05 BAC compared to drivers with no alcohol in their blood systems. Recent studies indicate that the relative risk of being killed in a single vehicle crash for drivers with BACs of .05 to .079 is at least 7 times that of drivers at .00 BAC (no alcohol) and could be as much as 21 times that of drivers at .00 BAC depending upon the age of the driver (Voas et al., 2012; Zador et al., 2000). These risks are significant.
- Lowering the illegal per se limit to .05 BAC is a proven effective countermeasure which has reduced alcohol-related traffic fatalities in several countries, most notably, Australia. While studies in Europe and Australia each use a different methodology to evaluate these effects, the evidence is consistent and persuasive that fatal and injury crashes involving drinking drivers decrease on the order of at least 5% – 8% and up to 18% after a country lowers their illegal BAC limit from .08 to .05 BAC (Brooks & Zaal, 1993; Homel, 1994; Nagata et al., 2008). A meta-analysis of international studies on lowering the BAC limit in general found a 5.0 percent decline in non-fatal alcohol-related crashes, a 9.2 percent decline in fatal alcohol-related crashes from lowering the BAC from .10 to .08, and an 11.1 percent decline in fatal alcohol-related crashes from lowering the BAC to .05 or lower. The study estimated that 1,790 lives would be saved each year if all states in the United States adopted a .05 BAC limit (Fell & Scherer, 2017 in press).
- .05 BAC is a reasonable standard to set. A .05 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 4 drinks for the average 170 lb. male to exceed .05 BAC in two hours on an empty stomach (3 drinks for the 137 lb. female). The BAC level reached depends upon a person’s age, gender, weight, whether there is food in their stomach, and their metabolism rate (NHTSA, 1994). No matter how many drinks it takes to reach .05 BAC, people at this level are too impaired to drive safely (McKnight et al., 2002).
- The public supports levels below .08 BAC. The National Highway Traffic Safety Administration (NHTSA) surveys show that most people would not drive after consuming two or three drinks in an hour and believe the limit should be no higher than the BAC level associated with that (Royal, 2000). That would be .05 BAC or lower for most drivers. A recent survey indicated that 63% of drivers in the US support lowering the illegal BAC from .08 to .05 (Arnold & Tefft, 2016).
- Most industrialized nations around the world have set BAC limits at .05 BAC or lower. All States in Australia now have a .05 BAC limit. France, Austria, Italy, Spain and Germany lowered their limit to .05 BAC, while Sweden, Norway, Japan and Russia have set their limit at .02 BAC (WHO, 2013).
- Further progress is needed in reducing alcohol-impaired driving. Progress in reducing impaired driving has stalled over the past 20 years in several countries (Dang, 2008; Fell et al., 2016). Lowering the BAC limit from .08 to .05 will serve as a general deterrent to all those who drink and drive that the government is getting tougher on impaired driving and society will not tolerate impaired drivers (Fell and Voas, 2014). Such legislation typically reduces the number of drinking drivers involved in fatal crashes at all BAC levels (BACs>.01; BACs>.05; BACs>.08; BACs>.15) (Voas et al., 2000; Wagenaar et al., 2007; Hingson et al., 1996).
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