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Testimony to the Committee on Transportation, Public Utilities, Energy and Technolgy Utah Senate on House Bill 155, Salt Lake City, Utah
T. Bella Dinh-Zarr, PhD, MPH
Salt Lake City, Utah

Thank you for inviting the National Transportation Safety Board (NTSB) to offer testimony concerning the issue of alcohol-impaired driving. NTSB recommends that all states lower their allowable per se blood alcohol concentration (BAC) limit from 0.08 to 0.05 percent or lower.

The NTSB is an independent federal agency charged by Congress with investigating every civil aviation accident in the U.S. and significant accidents in other modes of transportation-railroad, highway, marine and pipeline. The NTSB determines the probable cause of each accident it investigates and makes safety recommendations aimed at preventing future accidents. In addition, the NTSB carries out special studies concerning transportation safety and coordinates the resources of the Federal government and other organizations to assist to victims and their family members affected by major transportation disasters. The recommendations that arise from our investigations and safety studies are our most important product.

The Alcohol-Highway Safety Problem

More deaths result from motor vehicle crashes than from crashes in all other transportation modes combined. Almost 95 percent of all transportation related deaths each year result from highway crashes; and, more than 30 percent of those deaths nationwide involve an alcohol-impaired driver. In 2015, more than 32,600 people died in motor vehicle crashes, and almost 10,000 of those deaths occurred in crashes involving an impaired driver. During that same year, 63 people died in alcohol-related crashes in Utah.

In recent years, US success in addressing drunk driving crashes has plateaued and progress to drive the total number of highway deaths toward zero has sharply reversed. Total highway deaths increased 7.2% from 2014-2015, and it is estimated that they increased 10.4% year-over-year from the first half of 2015 to the first half of 2016.

According to the Centers for Disease Control and Prevention (CDC) Behavioral Risk Factor Surveillance System survey, an estimated 4 million people drove impaired and approximately 121 million alcohol-impaired driving episodes occurred in 2012, which takes a substantial economic toll. A 2012 study by the Pacific Institute for Research and Evaluation estimated that the total cost of alcohol-involved crashes was $132 billion, comprising monetary costs (such as medical costs, emergency services, market productivity, legal costs, travel delay,

and property damage) and quality-of-life losses (reflecting how lives are changed as a result of a functional impairment, such as losing a limb).

Clearly, much needs to be done to reduce this ongoing tragedy. The cause of these deaths is well understood and preventable, yet even the most concerted efforts have not kept thousands of lives from being lost each year. If traditional methods are no longer reducing the problem, we must consider new—and possibly challenging—initiatives to combat this issue.

Blood Alcohol Concentration (BAC) and Driving

Since 2004, all states have had a per se BAC limit of 0.08 for noncommercial drivers age 21 and over. Many people believe that if a driver’s BAC is under the current legal limit of 0.08, the driver is safe to drive. In reality, impairment begins well before that level and a driver’s fatal crash risk has at least doubled by the time they reach 0.08. Some studies indicate it may be many times higher.

Alcohol is a drug that depresses the central nervous system and affects cognitive performance, mood, and behavior. The negative effects of alcohol on driving-related skills, such as divided attention, vigilance, tracking, perception, and reaction time are present with BAC levels as low as 0.01. Alcohol’s effects become more severe as more alcohol is consumed. Studies have shown that crash risk is significantly higher when a driver’s BAC is at 0.05 or higher, and that crash risk climbs rapidly at BAC levels that exceed 0.08. One study found that the risk of fatal crash involvement at BACs between 0.05 and 0.079 ranged from about 3 to 17 times greater, depending on the age of the driver and the type of fatal crash. Another study found that at a BAC of 0.05, drivers are 38% more likely to be in a crash than are sober drivers. At a BAC of 0.08, crash risk is 2.69 times higher. Beyond impairing driving-related performance and increasing crash risk, alcohol use is also associated with reduced seat belt use, which increases injury severity in the case of a crash.

Lowering BAC limits has been associated with reductions in impaired driving crashes and fatalities. For example, 14 independent studies conducted in the United States found that lowering the BAC limit from 0.10 to 0.08 resulted in reductions in alcohol-related crashes, fatalities, or injuries of 5–16 percent. Other studies have found similar results. In 2012, the CDC listed 0.08 per se BAC laws among the “top 20 violence and injury practice innovations since 1992.”

Research also has demonstrated the effectiveness of setting per se BAC limits below 0.08 for novice drivers, commercial drivers, or all drivers. For example, six studies that examined the effectiveness of low-BAC laws for young or novice drivers found reductions in injuries or crashes after enactment of the laws, and in three of the studies, the reductions were statistically significant. A study of commercial drivers found that changes to commercial driving laws, including reducing the BAC to 0.04 percent, were associated with a 23 percent reduction in risk of alcohol involvement in fatal crashes by motor carrier drivers. Similarly, a study of per se BAC reductions in several European countries found that the change from a 0.08 to a 0.05 BAC limit reduced traffic fatalities by 8–12 percent among people aged 18–49. Finally, in Australia, fatal crashes decreased significantly in two states (by 18 percent in Queensland and by 8 percent in New South Wales) after those states lowered their per se BAC limits from 0.08 to 0.05.

National and international traffic safety and public health organizations, including the American Medical Association, the World Health Organization, the World Medical Association, and the Association for the Advancement of Automotive Medicine have advocated setting BAC limits at 0.05 or lower. Respected traffic safety and public health organizations around the world view BAC levels higher than 0.05 as posing unacceptable risk for driving. More than 100 countries have already established per se BAC limits at or below 0.05.

Although lowering the per se BAC threshold may seem counterintuitive when the majority of alcohol-impaired drivers in fatal crashes have BAC levels well over 0.08, research on the effectiveness of laws limiting BAC levels has found that lowering the BAC limit changes the behavior of drivers at all BAC levels. Consequently, reducing the per se BAC limit could reasonably be expected to have a broad deterrent effect, thereby reducing the risk of injuries and fatalities from crashes associated with impaired driving.

The NTSB has concluded that changing legal per se BAC limits from 0.08 to 0.05 or lower would lead to meaningful reductions in crashes, injuries, and fatalities caused by alcohol-impaired driving. Therefore, the NTSB has recommended that the 50 states, Puerto Rico, and the District of Columbia establish a per se BAC limit of 0.05 or lower for all drivers who are not already required to adhere to lower BAC limits.


In conclusion, BAC levels as low as 0.01 have been associated with driving-related performance impairment, and BAC levels as low as 0.05 have been associated with significantly increased risk of fatal crashes. We expect that changing per se BAC limits from 0.08 to 0.05 or lower will lead to meaningful reductions in crashes, injuries, and fatalities caused by alcohol-impaired driving.

H.B. 155 demonstrates Utah’s commitment to addressing impaired driving and the preventable crashes, injuries, and deaths that result. NTSB encourages you to enact legislation to implement this important change. Thank you again for your consideration of this important issue.