Picture this: You’re at a dinner party and someone whips out a freshly rolled joint. You, a non-smoker with work the next day, immediately cover your nose, in anticipation for what’s about to happen next. The room fills up with smoke and suddenly you start feeling lighter, thinking about whether or not you locked the car door before coming upstairs to the party.
Did you just get a contact high? In most cases, probably not.
But before you consider this myth debunked, there’s something you should know. According to science, secondhand highs from intense cannabis smoke are real. A classic example is “shotgunning” or breathing in cannabis smoke and directly exhaling into an individual’s mouth. The effects aren’t as pronounced, but they can be felt, undeniably.
Rare, But Possible
For unintentional, indirect contact highs that are commonly associated with crowded concerts and unventilated spaces, it would take a significant amount of secondhand smoke to feel the cerebral effects of cannabis. To test how much cannabis smoke it would take to get bystanders high, scientists from Johns Hopkins University School of Medicine conducted a study, which was published in the journal Drug and Alcohol Dependence.
During the trials, a total of 12 participants – six smokers and six non-smokers – were crammed inside a 10” x 13” room. Scientists then provided every participant from the smoking group with 10 potent cannabis joints to consume inside the space. Researchers conducted the experiment two times. The first session was ventilated with fans to mimic a residential bathroom; while the second session did not make use of a fan, which closely resembled the back of a car or a closet.
While the six smokers were puffing away, the non-smoking group was asked to sit patiently inside the space for an hour. After the non-ventilated session, scientists collected blood and urine samples from the non-smoking group. Unsurprisingly, all of the participants tested positive for THC. Traces of cannabis in blood samples were present and lingered for up to three hours after. One participant tested positive via a urine test four hours after the trial. At the extreme end of the results, four non-smoking participants tested positive for THC, when tested periodically between two and 22 hours after the experiment.
The key takeaway here is that the non-smokers registered noticeably lower cannabinoid levels (via urinalysis) during the second session with a ventilation fan available to scatter and filter the smoke. Moreover, the non-smoking group only reported feeling hungry, but still alert.
During the first unventilated session, the non-smoking participants cited feeling tired, less alert and pleasant. To solidify their findings, researchers asked the non-smoking group to perform a series of grid tests. After exposure without a ventilated fan, the non-smoking participants responded quickly but made more errors.
“We found positive drug effects in the first few hours, a mild sense of intoxication and mild impairment on measures of cognitive performance,” explained senior author Ryan Vandrey. “These were relatively slight effects, but even so, some participants did not pass the equivalent of a workplace drug test.”