December is National Impaired Driving Prevention Month. In 2017, there were more than 1,800 fatalities in alcohol-related crashes in which drivers had a BAC below .08, the legal drunken driving limit.

Here are five things to know about the dangers and consequences of impaired driving, as well a tips for staying safe on the road from the National Highway Transportation Safety Administration.

1. December is particularly dangerous

According to NHTSA’s Fatality Analysis Reporting System, 839 people nationwide died in traffic crashes involving a drunk driver during the month of December 2018.

In the weeks surrounding Christmas and New Year’s Day in 2018, there were more drunken driving related fatalities than any other holiday period that year.

2. Know the legal limits — and your own

It’s illegal to drive with a blood-alcohol concentration of .08 or above in 49 states and the District of Columbia. However, even a small amount of alcohol can affect one’s driving ability.

A variety of factors can affect one’s level of impairment including the number of alcoholic drinks consumed, the rate of consumption, body weight, gender and whether or not an individual has eaten prior to drinking.

“Because of the number of factors that affect BAC, it is very difficult to assess your own BAC or impairment,” an article by the NHTSA said. “Even small amounts of alcohol affect one’s brain and the ability to drive. People often swear they are ‘fine’ after several drinks – but in fact, the failure to recognize alcohol impairment is often a symptom of impairment.”

3. Alcohol isn’t the only impairing substance

Illegal drugs like marijuana, cocaine and methamphetamine affect a driver’s ability to safely operate a motor vehicle and can also lead to DUI and drug possession charges.

Though not illegal, medications may also create a danger for drivers and others on the road.

“Some prescription and over-the-counter medicines can cause extreme drowsiness, dizziness, and other side effects,” the NHTSA article said. “Read and follow all warning labels before driving, and note that warnings against ‘operating heavy machinery’ include driving a vehicle.”

4. A DUI is costly

On average, those convicted of a DUI or DWI will spend more than $10,000 in attorney’s fees, fines, court costs, lost wages, higher insurance rates,and towing services.

But money is only part of the equation. Driving while impaired can lead to the loss of a job, a suspended or revoked license, and jail time.

Worse yet, impaired drivers who are lucky enough to survive a crash may still have to live with the knowledge that their choices resulted in the injury or death of a stranger, a neighbor, friend or family member.

5. There are many ways to get home safe

Individuals who intend to consume alcohol are urged to make arrangements for a safe ride home well before their first drink.

Options include staying the night, designating a sober driver, calling friends or family for a ride, taking a taxi or ride-sharing service, or relying on public transportation.

The NHTSA also encourages drivers to download its free SaferRide app, which can help users call a taxi or friend and identify their current location.