What Are the Side Effects of Secondhand Marijuana Smoke?
Marijuana smoke is created whenever someone burns the leaves, flowers, stems, or seeds of the cannabis plant. Marijuana is used by an average of 26 million Americans per month. It’s been studied for some medical uses.
But despite marijuana’s prevalence, its safety is sometimes in dispute. Smoking it, or being near someone else who is smoking it, does cause side effects.
Marijuana contains a chemical called THC, which can block pain and bring on a feeling of relaxation to people who breathe it in or consume it. Smoking weed has depressant, hallucinogenic, and stimulant effects. Inhaling THC can also impair your ability to concentrate and to operate a car.
Whenever you’re breathing in THC, it’s possible to get high. Effects of THC vary from person to person, as well as how much of the chemical you’re exposed to.
Drug test results can differ for people who are exposed to secondhand marijuana smoke and people who smoked marijuana.
In 2015, a small study of six smokers and six nonsmokers showed that marijuana smoked in highly concentrated quantities could trigger a positive urine drug test among people who were simply exposed to the smoke in an unventilated room.
However, ventilation during marijuana exposure, as well as how often exposure occurred, were critical factors in what the drug test result would be.
For example, smelling marijuana smoke in passing once in a while is a lot different from living with a habitual marijuana smoker who uses marijuana in your presence regularly.
Another small study attempted to mimic a more true-to-life example.
Rather than stick nonsmokers in a closed, unventilated room for long smoking sessions, these study participants spent three hours in a coffee shop where other patrons were smoking marijuana cigarettes.
After their exposure to secondhand marijuana smoke, participants were tested for THC. While a trace amount of THC did show up in their blood and urine, it wasn’t enough to trigger a positive drug test result.
It was unlikely that any contact high was passed during this study.
With that being said, getting a contact high is possible.
Being near marijuana smoke often and in poorly ventilated areas (like a car with the windows rolled up or a small bedroom without a fan) may result in feeling a limited amount of the effects that the person smoking experiences.
But catching a whiff of marijuana fragrance through your apartment window or entering a room where people were smoking several hours ago is very unlikely (maybe even impossible) to affect you at all.
There isn’t much by way of clinical data to understand if secondhand marijuana smoke is as bad for your health as tobacco smoke.
According to the American Lung Association, regularly smoking marijuana yourself can damage your lungs and weaken your immune system.
And a 2016 study on rats showed that just one minute of secondhand marijuana smoke impaired lung function for at least 90 minutes — which is longer than the lungs are affected by tobacco secondhand smoke.
Secondhand marijuana smoke exposes you to many of the same toxic chemicals as smoking it directly does. Because of this, the American Lung association recommends that people avoid exposure to secondhand marijuana smoke.
Contact high may be less common than we think, but it’s possible. Here are some of the other side effects and symptoms of secondhand marijuana smoke exposure.
Smoking weed can slow your reaction time when you’re on the road. If you have high levels of THC in your blood from secondhand marijuana smoke, it might have the same effect.
If you’re around marijuana smoke for a long period of time, you may begin to feel lightheaded or dizzy.
One effect of the THC in marijuana is the feeling of calmness it gives some users. For others, this calmness can take the form of feeling tired or lethargic.
Researchers are still trying to understand the connection between excessive marijuana exposure and mental health. It appears that marijuana use can trigger or worsen some mental health conditions, including depression.
No link has been established between secondhand smoke marijuana exposure and depression.
The legal and medical use of marijuana is changing rapidly, but that doesn't mean it's safe for everyone to be exposed to it. Here's what you need to know.
Can you really get a secondhand high or contact high?
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- Is THC active after cannabis smoke is exhaled?
- Are there any other studies on secondhand highs?
You’ve probably heard the term “ secondhand high ” before. Also known as a contact high, the concept has become a popularized plot point in films and TV shows. You may have even been to a smoky concert hall yourself and walked away feeling a little lightheaded, even if you never took a single puff.
This could be concerning for those who fear that exposure to secondhand weed smoke could get them involuntarily stoned or cause them to fail a drug test . Therefore, it’s important to know whether second-hand cannabis smoke can get you high or enter your system.
So, do you have to inhale weed to get high ? Or can you really get a secondhand high from being around other people smoking cannabis? Is it really a thing?
According to a 2015 Johns Hopkins University study — the answer is both yes and no.
Researchers started with a dozen people — six cannabis smokers and six non-smokers. In the first experiment, all 12 subjects spent an hour together in a small unventilated room, during which time each smoker went through 10 “high-potency” joints (with 11.3% THC content). Afterward, the non-smokers reported feeling “pleasant,” more tired, and less alert. And sure enough, their blood and urine tests came up positive for THC .
The second experiment repeated the scenario, but this time in a room with ventilation . The non-smokers in this experiment later said they felt “hungry” — the study did also finish up around lunchtime — but none of them tested positive for any noticeable amount of THC .
Researchers concluded that being exposed to marijuana smoke under “extreme conditions” can indeed give non-smokers a contact buzz. Outside of that very limited scope, though, any secondhand effects you might feel around cannabis smoke are likely to be the result of the power of suggestion. You can’t get high from catching a whiff of someone’s joint while walking down the street, but you will feel some effects if you are sitting in an unventilated enclosure filled with smoke, also known as hotboxing.
In other words, if you spend a lot of time in a small room with the windows sealed shut while your friends are smoking, your blood and urine might test positive for THC and you might feel its effects. But outside of that, it is more likely that your “contact high” is all in your head, so to speak.
Is THC active after cannabis smoke is exhaled?
If we pull a page from the 1999 British Journal of Anesthesia , we learn that the lungs absorb most of the THC when cannabis smoke is inhaled. Researchers have discovered that approximately fifty percent (50%) of THC and other cannabinoids present in cannabis cigarettes, or joints, make it into the smoke and are inhaled.
“Experienced smokers, who inhale deeply and hold the smoke in the lungs … virtually all of the cannabinoids present in the mainstream smoke enter the bloodstream,” leaving very little THC in the surrounding air to be inhaled and absorbed by a passive inhaler.
In order to get secondhand high, you would need to be in an unventilated room for some time to feel anything, otherwise the cannabinoids will have disappeared into the air before even reaching you.
When considered together, this and the 2015 Johns Hopkins study show you would need to be in an unventilated room for some time to feel anything. More than likely, though, the cannabinoids will have disappeared into the air before even reaching you.
Are there any other studies on secondhand highs?
Studies performed during the mid- to late-1980s investigating the mystery of the secondhand high determined that the acute toxicity of cannabis was extremely low, therefore making it difficult to feel the effects without direct inhalation. While their conclusions may still apply, cannabis has changed over the years and the studies may need reexamination.
The THC potency of cannabis has increased as cultivation techniques and technologies have advanced. In the early 1970s, the average joint contained roughly 10 mg of THC, whereas a modern joint may contain 60-150 mg of THC or more. The THC potency in today’s marijuana flowers is far greater than the weed from the 1960s and 1970s, therefore much of the early research produced from studying secondhand highs may be outdated.
While there’s an abundance of research demonstrating the adverse health effects of secondhand exposure to cigarette smoke, there is little evidence to suggest that secondhand marijuana smoke carries the same detrimental health risks as tobacco smoke. Considering that past research has found marijuana smoke to be less carcinogenic than cigarette smoke , there’s doesn’t seem to be an immediate public health concern regarding secondhand weed smoke. That being said, as long as you’re not stuck in a poorly ventilated room during a heavy smoke session, you shouldn’t be concerned about feeling stoned or having THC enter your system.
Can you get high from smelling weed in the air or walking through the remnants of secondhand weed smoke? No, it’s highly unlikely you’ll experience a secondhand high or have cannabis byproducts show up on a drug screening. As the 2015 Johns Hopkins University research study shows, in order to catch a secondhand high, you’d have to be under extreme conditions and lack proper ventilation.
Nonetheless, weed smokers should still be respectful of people who don’t consume cannabis. The next time you spark one up, try to be aware of your surroundings and make an attempt to keep the smoke and strong odor away from non-smokers. To enjoy a smooth smoking session without affecting your non-partaking neighbors, cannabis users should spark up in well-ventilated areas to ensure passive inhalers will not feel the effects of the smoke or test positive for weed.
Ever wonder if you can get high from smelling weed? Learn if you can really get a secondhand high.