
In concerts, at house parties, even in the hallway of apartment buildings, you may have come into contact and been exposed to secondhand marijuana smoke.
In situations like these, people often worry how breathing someone else’s marijuana smoke affects them. A couple of common questions and the answers may help you see through the fog of this smoky situation.
Can you get high from inhaling secondhand marijuana smoke?
Probably not.
You may have heard the phrase “contact high,” about someone breathing secondhand marijuana smoke and feeling a buzz. Studies have found that in extreme conditions, with lots of smoke blown directly into your face, you can feel the high and it can even show up in a urine test. But this is not a normal circumstance.
Research shows that very little THC is exhaled back into the air when a smoker exhales. So little, in fact, that if you sat in a room while people exhaled the smoke of four marijuana cigarettes (sometimes called joints) in one hour, you wouldn’t get high. You would have to be trapped in a room breathing the smoke of 16 burning joints before you started to show signs of being high.
Can you fail a drug test from inhaling secondhand marijuana smoke?
Again, probably not.
Since the amount of THC exhaled by marijuana smokers is so low, it would take a lot of secondhand exposure to fail a drug test.
In a 2010 study, researchers measured the effect of secondhand marijuana smoke on non-marijuana smokers. The non-smokers were placed in a well-ventilated space with people casually smoking marijuana for 3 hours. The researchers then took blood and urine samples from the nonsmokers. They found that THC was present, but the amount was well below the level to needed to fail a drug test. Another study found similar results: Testing positive is rare and limited to the hours directly following exposure.
What are the health effects of inhaling secondhand marijuana smoke?
Researchers are still working to figure this out. We still don’t know how a person is affected if they live with a regular marijuana smoker. We also don’t know how higher amounts of THC in today’s marijuana cigarettes affects secondhand smoke.
A recent study on rats suggests that secondhand marijuana smoke can do as much damage to your heart and blood vessels as secondhand tobacco smoke. But that study has not yet been done on humans.
We also know marijuana smoke contains harmful and cancer-causing chemicals, the same way tobacco smoke does. But we still don’t know how it affects a person’s health in the long run. Lots more research still needs to be done.
Tell us in comments: what would you do if someone was smoking marijuana near you?
Update: Read the blog post, “Two More Things We’ve Learned About Secondhand Marijuana Smoke.”
Comments
It's not likely.
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Hi lula, it's not likely that you could inhale enough secondhand marijuana smoke to fail a drug test.
Hi Cece, it's not likely that you could inhale enough secondhand marijuana smoke to fail a drug test.
Probably not.
There has been a lot of research on the effects of secondhand tobacco smoke, but we currently don’t know very much about the effects of secondhand marijuana smoke. But just because there isn’t much research yet on it, doesn’t mean you should allow yourself to be exposed to it—especially when you find it physically uncomfortable. After all, it took decades to link tobacco to cancer and lunch and heart disease, in both smokers and those who were exposed to smoke.
We’re sorry to hear that your son may be exposed to secondhand smoke. Positive drug tests are rare for people exposed only secondhand to marijuana smoke, but might be higher for a child. We also do not know what affect secondhand smoke might have on a child’s developing brain. If you get a positive test, we recommend you consult a physician as well as whatever support system is in place to protect your child.
Positive drug tests are rare for people exposed only secondhand to marijuana smoke. Studies show that smoke would have to be blown directly into your face for a long period of time to show up on a drug test. It is possible, but most real life situations are not like that. How likely secondhand smoke is to impact a bystander’s drug test depends on the ventilation of the room, the amount of THC content of the marijuana being smoked (how strong it is), how much smoke someone is exposed to, for how long, and how long after that exposure a drug test is administered.
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