This Triples Risk of a Deadly Car Crash

Poor weather causes thousands of fatal car crashes each year, but the majority of car crashes actually occur under “normal” conditions.

Unfortunately, the condition of the weather can’t prevent deaths caused by the condition of the driver. Drivers who tested positive for drugs were three times more likely to be involved in a fatal car crash than sober drivers, according to a new study from Columbia University's Mailman School of Public Health.

Researchers used data from the 2007 National Roadside Survey of Alcohol and Drug Use by Drivers and the Fatality Analysis Reporting System to determine the percentage of car crashes related to positive drug and alcohol tests.

Approximately 31 percent of drivers involved in fatal crashes tested positive for at least one non-alcohol drug. By comparison, only 8.5 percent of fatal crashes were linked to rain and snow.

More than half of the drivers in all fatal car crashes tested positive for elevated levels of blood alcohol.

The study authors did warn that testing positive for these drugs did not necessarily guarantee impairment, but the numbers remain alarming.

"The possible interaction of drugs in combination with alcohol on driving safety has long been a concern," said Guohua Li, MD, professor of epidemiology and director of the Center for Injury Epidemiology and Prevention at Columbia, in a press release. "While alcohol-impaired driving remains the greatest threat to traffic safety, these findings about drugged driving are particularly salient in light of the increases in the availability of prescription stimulants and opioids over the past decade."

Car crashes killed at least 30,000 Americans each year from 1994 to 2011, according to the Fatality Analysis Reporting System.