Secondhand marijuana smoke harbors numerous health risks to exposed non-pot smokers. With the legalization of marijuana in many states, secondhand marijuana smoke exposure is becoming an increased cause of concern. Many people wonder whether secondhand marijuana smoke can cause a positive drug test.

Effects of Secondhand Marijuana Smoke on Drug Test

Many concerns have been raised about the effect of secondhand marijuana smoke on drug screens. People want to know if second hand marijuana smoke can cause a positive drug test. The National Institute on Drug Abuse (NIDA) confirmed that secondhand marijuana smoke may result in a contact high after considering multiple factors. The factors are marijuana potency, room ventilation, exposure period, etc.

Researchers looked into the amount of THC or delta-9-tetrahydrocannabinol (the psychoactive chemical in the cannabis plant) in people who did not smoke marijuana and spent 3 hours exposed to secondhand marijuana smoke in a well-ventilated space. Reports show THC in the samples of non-pot users. However, the amount was below the level to fail a drug test.

Another study reported that non-pot users exposed to high-THC marijuana (11.3% THC) for an hour in an unventilated room reported positive urine samples directly following exposure. A follow-up study said that non-users exposed to high-THC marijuana users in a confined space resulted in mild motor performance impairment.

Moreover, a subsequent study revealed that one minute of secondhand marijuana smokes exposure impaired flow-mediated dilation for 90 minutes compared to a 30-minute dilation impairment period recorded after secondhand tobacco smoke.

Therefore, it is safe to say that you most likely will not fail a drug test due to secondhand marijuana smoke exposure. There are no peer-reviewed studies that indicate its likelihood.

Health Risks of Secondhand Marijuana Smoke Exposure

Whether or not it results in a positive drug test, inhaling secondhand marijuana smoke may result in similar damage to blood vessels as secondhand tobacco smoke.

As per the results of a 2014 study, secondhand marijuana smoke resulted in a 70% reduction in rats’ blood vessel function. The study revealed that while blood vessel function was back to normal after 40 minutes with secondhand tobacco smoke. Rats exposed to secondhand marijuana smoke experienced prolonged reduced blood vessel function.

Reduced blood vessel function is associated with a higher risk of heart attacks, strokes, and atherosclerosis.

Harmful Chemical Components

Marijuana and tobacco are chemically alike. That means the harmful chemicals in cigarette smoke are likely present in marijuana smoke as well. Much like tobacco smoke, marijuana contains carcinogens, such as nickel, cadmium and benzene.

According to the study, secondhand marijuana smoke results in 20 times higher ammonia levels than secondhand tobacco smoke. Along with 3 to 5 times higher levels of aromatic amines and hydrogen cyanide.

Positive Drug Test  – Possible or Not?

Secondhand marijuana smoke produces THC levels different from those produced from active exposure. When a marijuana smoker exhales, very low THC levels are released into the air. That makes it highly unlikely for a non-pot user, under normal circumstances, to get a positive drug test result.