Does passive smoking really exist?

If you don't use cannabis, but spend evenings with pot smokers, you've probably wondered why you've experienced cannabis-like effects during the evening.

Just like passive smoking, Passive highs do exist. This phenomenon occurs when a person who doesn't use cannabis feels the «same» effects as a smoker when in close proximity to a user. Cannabis smoke contains cannabinoids, which can interact with non-smokers, especially if they're not used to it.

A 2015 study conducted by students at the John Hopkins School of Medicine in Baltimore, Maryland, sought to understand this phenomenon. These scientists tested cannabis smoke on twelve people: 6 smokers and 6 non-smokers. The subjects met together in a room made of Plexiglas and sealed with manually operated ventilation mechanisms at one-hour intervals. Some trials exposed subjects to rooms that were not ventilated, while other subjects were placed in a room with a ventilation rate of eleven air exchanges per hour.

The results of the experiment were conclusive. The researchers found that subjects who were in the room without ventilation, even without consuming directly, were positive for cannabis in urine tests. Non-smokers exposed to cannabis smoke for an hour or more may therefore have traces of THC in their system. «We found positive effects of cannabis in the first few hours, a slight intoxication and a slight decrease in cognitive performance,» explains Ryan Vandrey, professor at the Baltimore School of Medicine and one of the study's authors.

So passive smoking really does exist. To avoid this, open the windows and don't smoke your non-consuming buddies. At a certain level of exposure, they could even test positive for cannabis in a roadside drug test.

Mehdi Bautier