Most people who know someone who smokes cannabis has a story about how they could feel the effects of their friend’s second-hand at one time or another…
It’s such a popular anecdote to have that it’s become something of a trope in teen movies and TV shows.
But the truth is, it actually requires some pretty specific conditions to get any kind of actual effect from someone else’s smoke.
So, can secondhand smoke get you high? What about smoke from a vape?
For some people – whose job may rest on them being able to pass drug tests – this is a serious matter. In this article, we’ll learn all about it…
What is second-hand smoke?
Just in case there’s any confusion, second-hand smoke – sometimes referred to as “contact high” – is what happens when someone is smoking in your vicinity and you happen to breathe in the smoke after it comes out of their lungs.
Can you get high from second-hand smoke?
The answer to this question depends, in part, on how much of the cannabinoid THC (the organic compound in cannabis which is responsible for the psychoactive effects of imbibing it) as well as other cannabinoids have been absorbed by the first smoker.
A study by the British Journal of Anesthesia several decades ago found that, on average, around half of the active compounds are absorbed.
The actual amount depends on the experience of the first smoker:
- Most inexperienced smokers may not inhale for very long, meaning more of the active compounds are left in the smoke.
- Most experienced smokers will inhale for longer, absorbing almost all of the active compounds, leaving the smoke almost free of them.
Can you get a contact high from weed? What’s the evidence?
A great deal of the research done on whether you can get high from second-hand smoke was done 30 or 40 years ago.
This wouldn’t be a problem…
Except for the fact that most modern strains of cannabis have been deliberately cultivated to be as much as six to fifteen times stronger than the cannabis which was available at the time of those original studies.
However, there is one modern study – conducted by John Hopkins University in 2015 – which seems to have the answer to the question…
The John Hopkins study
The study from John Hopkins University involved placing six smokers and six non-smokers in a room for an hour, having the smokers smoke some strong joints (cannabis cigarettes) and testing the results.
The researchers found that there was one overriding factor governing whether you can get a contact high from weed:
How well ventilated the room you are in is…
If you are in a well-ventilated room you are unlikely to feel any effects from second-hand marijuana smoke other than ones which might have been “suggested” to you. The researchers found that of the six non-smokers in their study, if the room was well ventilated, none of them would test positive for THC in their system or report any effects.
If you are in a small, non-ventilated room in the event that the room you are in has zero ventilation, everyone is smoking joints and there isn’t much space in the room in the first place, then the story is a little different. Of the non-smokers tested after an hour in these conditions, all had THC in their blood and urine.
Can you get high off second-hand vape smoke?
The same seems likely to be true for cannabis vape oil and the second-hand smoke it creates.
The relatively modern nature of the technology means that there haven’t been any scientific studies done as yet.
But as long as you’re not taking deliberate measures or often finding yourself in small, enclosed spaces with a whole bunch of heavy smokers, you should be fine.
So what does this mean for second-hand smoke highs?
The conclusion here is that if you’re walking down the street and you accidentally get some cannabis smoke in your face, you won’t be affected – nor is there any chance that you will get any measurable levels of THC in your system.
Remember – the six non-smokers in the John Hopkins study were actually in the same room as six people smoking (ten!) heavy joints and, when there was decent ventilation, they felt and had no side-effects whatsoever.
Only when what the researchers termed “extreme measures” were taken, was this not the case.
The importance of good etiquette
Of course, this doesn’t mean that people who smoke cannabis or like cannabis oil in their vape pen should go around blowing smoke in the faces of non-smokers.
A little politeness and a little good etiquette never hurt anyone:
- Keep an eye out for non-smokers so you aren’t accidentally leaving them down-wind.
- Consider when strong odors might be noticeable or disturb people.
- Make sure the area is well ventilated to protect people who don’t want to partake.
In fact, it’s for reasons like this that many people like to use vapes and vape pens.
They dramatically reduce the aroma and make imbibing cannabis much less obvious.