Alcohol and cannabis are the two most commonly detected substances in drivers who die in traffic crashes in Canada.

That’s why, to coincide with National Road Safety Week (May 15-21) the Canada Safety Council (CSC) is emphasizing the impacts of both substances.

“Safe driving requires your full, undivided attention at all times,” said Lewis Smith, Manager of National Projects at the CSC. “Being impaired dulls your senses, your reaction times and ultimately, your attention. With the May long weekend upcoming, we want National Road Safety Week to serve as a reminder to be proactive, not reactive, and make plans to ensure that if you’re impaired, you’re not driving.”

The CSC warns drivers that alcohol acts as a depressant and slows down the central nervous system, leading to delayed reaction times and impaired hand-eye coordination, judgment and concentration – skills that are vital for a motorist.

Cannabis can affect motor skills including body movement, balance and coordination. Perception of time is also impacted. The CSC says that, often, drug-impaired drivers will attempt to counteract the negative effects of cannabis by driving more slowly and methodically; however, this can lead to a driver remaining stopped at a traffic light or a stop sign for far longer than is reasonable, and this unpredictability can lead to a collision.

“It is also important to note that alcohol and cannabis can have a multiplicative effect, meaning that a driver who has consumed both alcohol and cannabis will be significantly more impaired than someone who has consumed one or the other,” added Smith.

According to Statistics Canada, 72,039 impaired driving incidents were reported by police in 2015. The rate of these incidents (201 incidents per 100,000 population) is at its lowest since this type of data started being recorded in 1986. Yet, the proportion of drug-related incidents (3,000) is double what it was in 2009, when drug-impaired data started being collected.