If you work at a business with a zero tolerance drug policy you are going to have to watch out for second-hand pot smoke.
Researchers at the University of Calgary say employees could fail workplace drug tests if they are in a poorly ventilated room where marijuana is being smoked for as little as 15 minutes.
Fiona Clement from the University of Calgary says it happens in situations where there are high concentrations of marijuana.
"You know, the house party you might go to where you're hanging out in the kitchen, the windows are closed and people are passing around a couple of joints. That kind of exposure, even if you're not partaking in the smoking, can lead to THC levels in your urine and your blood, 24 to 48 hours after you've been at the party."
Clement notes some companies have no-tolerance policies when it comes to drug use.
Recreational pot becomes legal in Canada next summer.