The impact of impaired driving: Why substances make for unsafe roads

It’s a simple fact: Driving while impaired makes roads unsafe for all of us.

Adolescents are among those most connected to driving safety concerns. The Centers for Disease Control and Prevention (CDC) names motor vehicle crashes as the second leading cause of death among teens in the United States. What the National Highway Traffic Safety Administration (NHTSA) adds: Around 25% of those crashes involve an underage drinking driver.

Types of impaired driving

Drunk driving - Consuming alcohol has a significant impact on driving abilities, particularly among teens. Youth experience a much higher crash risk when consuming alcohol than older drivers, even at the same blood alcohol concentration (BAC) levels.

The CDC identifies alcohol as the most common substance associated with impaired driving in the U.S. They explain that a BAC of 0.08 percent—or 0.08 grams of alcohol per deciliter—is the legal limit for driving as an adult. Yet any drinking of alcohol under the age of 21 is illegal. This makes all alcohol consumption among teens substance misuse.

According to the NHTSA, precise effects of alcohol vary by BAC levels. But they share that all alcohol consumption leads to:

• Reduced function of the brain
• Impaired thinking and reasoning
• Loss of muscle coordination

These functions are crucial to operating a vehicle, and teens limit their ability to perform them when having alcohol. This means they also lessen the security available to themselves and others on the road.

Drugged driving - Drugs can diminish driving safety as much as alcohol. The National Institute on Drug Abuse (NIDA) defines drugged driving as “driving a vehicle while impaired due to the intoxicating effects of recent drug use.” This can apply to illicit drugs as well as prescription or over-the-counter medications. The effects that drugs have on the brain and driving skills vary by substance.

As with alcohol, any drug use among adolescents serves as misuse. The side effects of drugs can lead to serious concerns for teens who drive under their influence.

How many teens drive impaired?

Engaging in substance misuse before driving is not uncommon among students. Some key statistics:

• The 2019 Youth Risk Behavior Survey found more than five percent of 9th through 12th graders surveyed had driven after drinking alcohol in the past month. One in five students in the age group further reported having ridden with a drinking driver at least once during that time.
• A 2018 CDC study showed about nine percent of adolescents aged 16 to 20 reported driving under the influence of marijuana. The drug serves as the second most common substance linked to impaired driving.
• In 2020, the Substance Abuse and Mental Health Services Administration (SAMHSA) found nearly 1,400 youth aged 16 to 20 reported driving under the influence of alcohol or illicit drugs.

Teens may misuse more than one substance before driving. As the NIDA explains, drugs and alcohol are often taken together among those who drive impaired. In these cases, the driving risks from substances only escalate.

Connected safety hazards

Substance misuse can lead teens to experience other safety hazards on the road. The 2019 Youth Risk Behavior Survey showed a strong association between adolescents’ drunk driving and other driving-related risk behaviors. They found students who had driven after drinking alcohol at least once in the last month were:

• More than one and a half times as likely to not always wear a seat belt
• More than two times as likely to have texted while driving than students who had not driven after drinking alcohol
• Nearly five times as likely to have ridden with a drinking driver

With more safety hazards comes increased likeliness of teens encountering severe consequences. This includes vehicle crashes and crash deaths.

How often does impaired driving lead to vehicle crashes?

Vehicle crashes among teens occur often and with fatalities. The CDC explains that teen drivers aged 16 to 19 are nearly three times as likely to be involved in a fatal crash than drivers aged 20 or older. They add that close to 2,400 students aged 13 to 19 died in vehicle crashes in 2019 alone—an average of seven teens per day.

How many of these crash deaths were influenced by substance misuse? In 2019, the NHTSA reported that 24 percent of young drivers 15 to 20 years old who were killed in crashes during the year had BACs of .01 or higher. As many as 82 percent of the young drivers who had alcohol in their systems had BACs of .08 or higher.

The number of crashes influenced by drugged driving is more difficult to determine for many reasons. This includes that a roadside test for detecting drug levels in the body does not currently exist. But in 2016, the Governors Highway Safety Association (GHSA) found close to 44 percent of fatally-injured drivers tested positive for drugs. More than half of the drivers tested positive for two or more.

Learn more about impaired driving among teens

Navigating routes to prevention as a parent

Part of keeping students safe on the road comes from choosing safe vehicles for them to drive. But most importantly, parents must teach their teens safe behavior to engage in when getting behind the wheel. When adolescents are exposed to impaired driving at a young age as passengers, they are more likely to engage in the behavior when of a driving age themselves.

To help parents prevent their teens from driving impaired, the CDC offers several tactics, including:

• Provide teens with a safe way to get home if their driver has been drinking, such as picking them up or paying for a cab
• Model safe driving behavior
• Consider tools like parent-teen driving agreements that cover safe driving habits, and more