Weed Testing: Does Secondhand Marijuana Show Up On Drug Tests?

If somebody near you smokes weed but you don’t, would it show up on your drug test? This is a common question among people who are exposed to marijuana users, whether for recreational or medical purposes. The concern is real for those who are looking for employment or trying to get clearance for whatever reason, especially in states where cannabis use is not as liberal as others.

The future of public marijuana use shows a lot of promise and many cities already allow it in specific public spaces. However, not all cities are as open yet and there remain agencies and organizations that still treat marijuana use as a major factor for approvals and admissions.

So does second-hand marijuana show up on drug tests? Should you be worried if a family member or friend is using it near you?

It won’t show up on tests and there’s nothing to worry about. There are several studies to prove this.

In 1985, researchers tried confining non-cannabis users in a car with those who did smoke for 30 minutes. They then tested the non-smokers to see if their bodies showed traces of THC. The result was they did find some THC but only in very small amounts, not enough to get them high.

About 30 years later, another study looked into second marijuana effects and place pot and non-put users in one room for an hour. After the test, the non-smokers reportedly felt some effects of marijuana and they tested positive for THC for two to 22 hours. However, while it was found in their blood, they weren’t high. It was only because they were in extremely unventilated conditions.

Will secondhand marijuana exposure lead to a failed drug test? Not really. Again, the studies subjected the participants in extremely unventilated environments. John Hopkins scientists said that if you have been riding a vehicle for hours with heavy marijuana smokers, you are not likely to have any issues passing a drug test.

Times Colonist’s resident physician columnist Dr. Keith Roach also said that secondhand pot exposure will not likely show up in urine test results. The lab tests will show some level of THC but laboratories have a threshold for declaring a sample to be positive, especially when it was taken out of a passive environment.

There are many other studies that show that while secondhand pot exposure will show up in tests, it will not be significant enough to fail one. That said, you may continue being friends with your marijuana fan friends and show up confidently for exams the next day.