Medically Reviewed by
Jason Crawford

Article Last Updated on January 10, 2023

Workplace drug testing in the US has been around ever since the US President Ronald Regan first required it for federal employees in 1986, after which other businesses followed suit. As a result of that, different countries around the world started implementing their own policies about workplace drug testing. In recent years, even more companies require regular drug testing for their employees, and as drug testing regulations increase, people are researching what affects positive drug test results besides, of course, actively consuming marijuana.

Since the start of 2020, drug use has increased drastically as a result of the coronavirus (Covid 19) pandemic, with cannabis taking the first place as the most commonly used drug. People have increased the use of both medical marijuana and recreational marijuana. During these stressful times, the psychoactive effects of tetrahydrocannabinol (THC), and the calming effects of cannabidiol (CBD), have been utilized by cannabis users who want to reduce their anxiety and improve their mental health, reduce chronic pain, and fight insomnia. 

But, how does this powerful plant affect people who inhale second-hand smoke from weed? And can you fail a drug test from secondhand smoke?

Effects of Secondhand Smoking

A group of friends finding themselves in a hotbox session where marijuana is smoked for hours is a very common situation nowadays. And while the people who are smoking are voluntarily choosing to smoke, what happens to those who ingest this secondhand smoke? Does this smoke harm the individuals who don’t smoke?

To begin with, inhalation of cannabis smoke can cause an abundance of CO2 in the room and slight oxygen deprivation in adults. Moreover, even tobacco smoke exposure can be very harmful to a child, so it would be best if children aren’t brought to rooms where they could inhale secondhand marijuana smoke.

Can You Get “Contact High” From Secondhand Cannabis Smoke?

In order to find out if people would get high from secondary marijuana smoke, a 2010 study researched the cannabinoid concentrations in the blood and urine of people staying at a coffeeshop in Amsterdam for 3 hours. The tests showed that the subjects had absorbed small quantities of THC, but those weren’t enough for them to get high.

A new study by the Johns Hopkins University School of Medicine on the subject of nonsmokers exposed to secondhand smoke has researched exactly that. The research was done on 12 participants who sat in a 10-by-13-foot acrylic-walled room in which 6 people were smoking 10 high-potency cannabis cigarettes, and 6 people weren’t smoking marijuana. The results were published in the Journal of Analytical Toxicology.

The first exposure was with the fans turned on, and the second with the fans turned off. The results showed that nonsmokers exhibited other side effects from the secondary smoke, but a high wasn’t one of them

Moreover, the National Institute on Drug Abuse (NIDA) also reported that it would be unlikely for someone to get contact high from secondhand marijuana smoke after having researched factors like drug potency, hours of exposure, and room ventilation. 

So, to answer the question – no, you aren’t likely to get high from inhaling secondhand smoke.

So, Will You Fail Your Drug Test From Secondhand Marijuana Smoke?

During the previously-mentioned study, smokers’ and nonsmokers’ blood, urine, saliva, and hair were tested for the presence of THC at regular intervals. The study found it unlikely that people exposed to secondhand marijuana smoke would test positive for marijuana. The only test that turned out positive was the urine test, although, in order for it to turn out positive, you would need to get tested immediately after exposure. One of the researchers from the study,  Herrmann, concluded that “it’s really hard to get a positive drug test result from passive smoke unless you’re under extreme conditions.”

If you are taking an oral test, you would be safe to take an oral fluid test after 30 minutes following exposure, according to a 2004 research. So, in order for you to get a clean drug test, just refrain from staying in a room where cannabis is smoked 30 minutes prior to taking the test.

Does Secondhand Smoke Pose Other Health Risks?

While secondhand smoke is unlikely to get you high, you may experience other health risks if you are staying in a room where cannabis is smoked.

Even though not a lot of research has been done on the subject, secondhand exposure to marijuana smoke in an unventilated room can cause increases in heart rate, and minor levels of performance impairment on some behavioral/cognitive assessments. This may affect driving skills and, as a precaution, people should refrain from driving a vehicle after exposure to cannabis smoke.

Also, as secondhand exposure to cigarette smoke can result in health risks, secondhand exposure to marijuana smoke poses similar health risks. It can affect blood vessel function, and the effects last longer when compared to secondhand tobacco smoke. (Xiaoyin Wang et al, 2016)

Inhaling secondhand smoke can also affect lung health and cause a heavy cough since it’s an irritant to the throat and lungs and contains chemicals and tar which are similar to tobacco smoke. Long-term exposure to marijuana smoke even raises concerns for lung cancer and lung disease. (Donald P Tashkin et al, 2013)

In order to avoid this, it would be best if you regularly ventilate the room in which cannabis is smoked. Also, make sure that you don’t drive or operate heavy machinery after being exposed to cannabis smoke.


Marijuana has been around for ages and a lot of people reap benefits from using it. But, people who don’t smoke are sometimes wary about staying in a room where cannabis is smoked in fear of getting high.

As the available research shows, it’s unlikely that passive exposure to cannabis smoke will lead to a high and a positive drug test. Although, being in a room with cannabis smokers and being exposed to secondhand smoke can result in other side effects. 

In order to avoid that, make sure that you stay in a ventilated room and make sure you are sitting further apart from the smokers. That way you won’t risk experiencing any side effects from passive weed consumption.

Additional Sources

Wang, X., Derakhshandeh, R., Liu, J., Narayan, S., Nabavizadeh, P., Le, S., Danforth, O. M., Pinnamaneni, K., Rodriguez, H. J., Luu, E., Sievers, R. E., Schick, S. F., Glantz, S. A., & Springer, M. L. (2016). One Minute of Marijuana Secondhand Smoke Exposure Substantially Impairs Vascular Endothelial Function. Journal of the American Heart Association, 5(8), e003858. https://doi.org

Tashkin D. P. (2013). Effects of marijuana smoking on the lung. Annals of the American Thoracic Society, 10(3), 239–247. https://doi.org/10.1513/AnnalsATS.201212-127FR

A passionate advocate for the benefits of cannabis. Fraser Horton, who has a background in botany and a strong love of nature, has spent years researching how cannabis affects the body and mind. He established Leaf Nation in 2020, where he has devoted himself to educating people about the legalisation of marijuana and its safe and responsible use. Fraser is committed to highlighting cannabis’ potential for improving wellness and working to dispel the stigma associated with its use.


The information presented on this page is provided as a public service to aid in education and is derived from sources believed to be reliable. Readers are responsible for making their own assessment of the topics discussed here. In no event shall Leaf Nation be held reliable for any injury, loss or damage that could happen if using or abusing drugs.