Estimation of the Potential Effectiveness of Lowering the Blood Alcohol Concentration (BAC) Limit for Driving from 0.08 to 0.05 Grams per Deciliter in the United States.

BACKGROUND

In 2013, the National Transportation Safety Board (NTSB) issued a report recommending that states lower the illegal blood alcohol concentration (BAC) limit for driving from 0.08 to 0.05 g/dl. The NTSB concluded that there is a strong evidence-based foundation for a BAC limit of 0.05 or lower. Most industrialized nations have already enacted a 0.05 illegal BAC limit. This study was undertaken to contribute to the scientific evidence as to whether lowering the BAC limit to 0.05 will be an effective alcohol policy in the United States.

METHODS

We accomplished our objective by: (i) conducting a meta-analysis of qualifying international studies to estimate the range and distribution of the most likely effect size from a reduction to 0.05 BAC or lower; (ii) translating this synthesis toward estimating the effects of reducing the current 0.08 BAC limit to 0.05 in the United States; and (iii) estimating the life-saving benefits of the proposed 0.03 reduction in the driving limit from 0.08 to 0.05 BAC.

RESULTS

In our meta-analysis of studies on lowering the BAC limit in general, we found a 5.0% decline in nonfatal alcohol-related crashes, a 9.2% decline in fatal alcohol-related crashes from lowering the BAC to 0.08, and an 11.1% decline in fatal alcohol-related crashes from lowering the BAC to 0.05 or lower. We estimate that 1,790 lives would be saved each year if all states adopted a 0.05 BAC limit.

CONCLUSIONS

This study provides strong evidence of the relationship between lowering the BAC limit for driving and the general deterrent effect on alcohol-related crashes.